JP7360312B2 - Leaky coaxial cable laying structure, leaky coaxial cable laying method, trough body for storing leaky coaxial cable, communication method and communication system using leaky coaxial cable laying structure - Google Patents

Description

The present invention provides a leaky coaxial cable laying structure in which a leaky coaxial cable is laid inside a trough, a leaky coaxial cable laying method, a trough body for storing the leaky coaxial cable, a communication method using the leaky coaxial cable laying structure, and Regarding communication systems.

2. Description of the Related Art Conventionally, leaky coaxial cables are sometimes installed along the tracks of railways and the like, for example. Such a leaky coaxial cable consists of an inner conductor, an insulator placed around the outer periphery of the inner conductor, an outer conductor placed around the outer periphery of the insulator and having slots (openings) at predetermined positions, and an outer conductor. It consists of an outer sheath that covers the cable, and support wires that support the leaky coaxial cable body made up of these.

A leaky coaxial cable is a conductor that has an antenna function in which the outer conductor has many slots depending on the frequency used in order to transmit signals and at the same time emit part of the signal energy as radio waves into the space along the cable. be. Such leaky coaxial cables are especially installed along railroad tracks, tunnels, underground malls, etc. where it is difficult for radio waves to propagate, and are used for applications such as train radio, business radio, FM broadcasting, mobile phones, and wireless LAN. be done.

If a leaky coaxial cable is laid directly on the ground, there is a possibility that the leaky coaxial cable will be stolen, the surface of the leaky coaxial cable may get wet with water, it may become contaminated, and its performance may deteriorate due to vibrations caused by wind. Therefore, a typical leaky coaxial cable has a support line around the outer periphery of the coaxial cable, and the leaky coaxial cable is laid by supporting the support line with a support member such as a fence or a post.

As a support member for such a leaky coaxial cable, for example, a leaky coaxial cable includes a cable holder that holds a leaky coaxial cable laid along a track for vehicle wireless communication, and a fixing fitting for attaching the cable holder. A supporting tool for the use of the hand has been proposed (Patent Document 1).

The cable holder of the leaky coaxial cable support disclosed in Patent Document 1 is made of a flexible elastic material. A bendable elastic plate portion is provided at the attachment site to the fixture. The cylindrical part that holds the leaky coaxial cable is molded integrally with the elastic plate part, and the elastic plate part can swingably support the leaky coaxial cable when the fixing fitting receives wind pressure from the track side. .

Further, the method for fixing a leaky coaxial cable in Patent Document 1 can disperse stress concentration by bending and deforming the cable holder even if the leaky coaxial cable swings. This prevents the leaky coaxial cable from being damaged by local bending fatigue, improves durability, and dramatically extends the life of the leaky coaxial cable.

In addition, a self-supporting leaky coaxial cable with support wires is suspended and laid in a signal leakage space set deep inside a closed space such as a tunnel or indoors, and the leaky coaxial cable is connected to a closed space. A cable installation method for a signal leakage system in a closed space has been proposed in which a power supply cable for feeding a signal from the outside is suspended (Patent Document 2).

Patent Document 2 relates to a cable installation method in a signal leakage system used for wireless transmission in a closed space such as a tunnel or indoors, and a power supply cable used therein. In the power supply cable of Patent Document 2, an insulator made of foamed resin is interposed between an outer conductor made of a ring corrugated pipe and an inner conductor arranged at the center thereof, and a support wire is provided along the coaxial cable body. It is a self-supporting cable. In Patent Document 2, a leaky coaxial cable and a power supply cable are supported via respective support lines by fixing fittings placed at appropriate locations in a closed space. The leaky coaxial cable is fixed in a closed space by tightening a pair of clamp fittings to an inverted L-shaped base fitting with bolts and nuts.

Further, a cable laying method has been proposed that allows the communication cable to be laid straight without applying high tension when pulling it out from the drum, and does not leave any curls or the like (Patent Document 3).

In Patent Document 3, a high-rigidity support and a leaky coaxial cable are integrally covered with a sheath. Further, the material or cross-sectional shape of the high-rigidity support is selected so that the rigidity of the high-rigidity support is greater than the rigidity of the composite of the leaky coaxial cable and sheath excluding the high-rigidity support. Thereby, the linearity of the entire communication cable can be ensured.

More specifically, in the invention of Patent Document 3, a highly rigid support body is held by a support fitting through a sheath. Then, the high-rigidity support body is tightened and fixed to the support metal fittings using bolts, and this is fixed to a wall surface or a utility pole. In this way, the communication cable is supported and fixed. At this time, since the entire communication cable maintains uniform linearity, the slot provided in the outer conductor of the leaky coaxial cable is always accurately oriented in one direction. Therefore, good communication becomes possible.

Furthermore, a leaky coaxial cable connector for a communication device has been proposed that uses a bundled leaky transmission line, in which a plurality of leaky coaxial cables are arranged in parallel at regular intervals, as an array antenna. Reference 4).

The multiple leaky coaxial cables of Patent Document 4 are used in a MIMO (Multiple-Input and Multiple-Output) communication system that uses multiple antennas on the transmitting side and the receiving side, respectively. A leaky coaxial cable consists of a linear center conductor, an insulator concentrically covering the center conductor, and a plurality of slots arranged periodically in the extending direction. and a sheath that concentrically covers the outer conductor. The plurality of leaky coaxial cables are arranged in parallel at regular intervals and connected by a leaky coaxial cable connector. The leaky coaxial cable connector includes a plurality of gripping parts that grip the leaky coaxial cable, a connecting part that connects each of the plurality of gripping parts, and an opening part that opens a part of the gripping part.

Furthermore, a leaky coaxial cable installation method that allows a leaky coaxial cable to be installed at low cost and a cable installation structure that can be constructed at low cost have been proposed (Patent Document 5).

The method for laying a leaky coaxial cable in Patent Document 5 first involves laying a metal overhead wire between the supports (hanging step), and temporarily fixing the leaky coaxial cable along the overhead wire (temporary fixing step). Next, a hanging device made of a spiral non-metallic wire is wound around the axes of the overhead wire and the leaky coaxial cable. The hanging tool is placed between the pillars while the overhead wire and the leaky coaxial cable are passed through the cavity formed by the hanging tool (stretching step). Finally, the temporary fixing of the leaky coaxial cable is released (temporary fixing release process). Through the above steps, the leaky coaxial cable can be laid. The method for laying a leaky coaxial cable in Patent Document 5 involves winding a hanging tool made of a spiral non-metallic wire material around the axes of the overhead wire and the leaky coaxial cable, and installing the overhead wire and the leaky coaxial cable in a cavity formed by the hanging tool. It is characterized by the tensioning process, in which the cable is inserted while the hanging device is stretched between the supports.

Further, the optical unit transmission has a structure in which the support wire, the leaky coaxial cable, and the pipe for transmitting the optical unit are coated in common, and the leaky coaxial cable, the support wire, and the pipe for transmitting the optical unit are arranged sequentially from bottom to top. A leaky coaxial cable with a common pipe has been proposed (Patent Document 6).

Normally, when a leaky coaxial cable is installed near a railroad track, each time a train passes, the leaky coaxial cable is exposed to the wind pressure of the train, causing large vibrations, which can cause fatigue failure of the metal material. For this reason, it is necessary to firmly fix the leaky coaxial cable, but if it is fixed firmly in this way, the workability of the disconnection work will be poor, and after the disconnection work is performed, the support wire must be fixed by some means to prevent the leaky coaxial cable and the pipe. You need to connect it to.

On the other hand, in the leaky coaxial cable with an optical unit transmission pipe disclosed in Patent Document 6, the pipe is placed above the support line, and the leaky coaxial cable is placed below the support line, so that the support line and the pipe can be stopped. The only thing that can be fixed with metal fittings and not supported is the leaky coaxial cable. For this reason, even if a leaky coaxial cable is installed near train tracks that are subject to strong wind pressure, it is less likely to sway compared to conventional leaky coaxial cables, and fatigue failure due to vibration is less likely to occur. Further, the leaky coaxial cable can be easily separated by simply cutting off the joint between the leaky coaxial cable and the support wire, and the pipe can be easily separated by simply separating the joint between the pipe and the support wire.

Japanese Patent Application Publication No. 2005-130543 Japanese Patent Application Publication No. 2002-135931 Japanese Patent Application Publication No. 2007-273247 Japanese Patent Application Publication No. 2016-019047 JP2008-220161A Japanese Patent Application Publication No. 09-26533

Here, when transmitting and receiving radio waves through the slots of the leaky coaxial cable, the direction in which the slots are formed relative to the target of transmission and reception is important. The orientation of this slot is determined by the relative relationship between slot spacing and wavelength. Therefore, when such a leaky coaxial cable is used for transmission and reception with a train, the leaky coaxial cable should be connected so that the slot of the leaky coaxial cable is appropriately arranged at a predetermined angle and at a predetermined interval with respect to the receiving antenna. need to be laid.

However, if the leaky coaxial cable is made swingable as in Patent Document 1, it is difficult to keep the direction of the slot constant in a predetermined direction. In addition, there is a possibility that performance may deteriorate due to water or contamination on the surface of the leaky coaxial cable, or due to vibrations caused by wind.

Similarly, the installation method of Patent Document 2 does not take into account installation in places where air pressure fluctuations are large, such as beside Shinkansen tracks, and is not a fixing method when affected by air pressure fluctuations. Further, as in Patent Document 1, there is a possibility that performance may be degraded due to water wetting or contamination on the surface of the leaky coaxial cable, or vibration due to wind.

In addition, Patent Document 3 has the same problems as Patent Documents 1 and 2, and it is necessary to adjust the rigidity and cross-sectional shape of the high-rigidity support, coaxial cable, and sheath composite, so it is difficult to apply it. There are limits to possible leaky coaxial cables.

Similarly, in Patent Documents 4 to 6, it is difficult to suppress the influence of wind, dirt, etc., and to keep the direction of the slot constant.

The present invention was made in view of these problems, and it is possible to maintain a constant orientation of the slot and to suppress the influence of wind from trains, etc., and the influence of water and pollution. We have developed a leaky coaxial cable installation structure, a leaky coaxial cable installation method, and a communication method and communication system using the leaky coaxial cable installation structure that can alleviate cable deterioration due to environmental temperature changes and ultraviolet irradiation. An object of the present invention is to perform good wireless communication with an on-vehicle antenna by using the above communication method and the above communication system. In particular, for this reason, in the trough installation structure for leaky coaxial cables, in addition to weather resistance and impact properties, communication is carried out between the cable in the trough and the train, so the trough absorbs radio waves or Since deterioration of transmission characteristics is a problem, the invention was designed to take into consideration the dielectric constant and communication characteristics of the trough structure used in the laying structure of the leaky coaxial cable. Furthermore, we have come to invent a communication method and a communication system using this.

The trough body includes a trough body and a trough lid made of resin, and a leaky coaxial cable housed in the trough body, and the trough body has a bottom part and side walls standing up on both sides of the bottom part, and the trough body has a bottom part and side wall parts standing up on both sides of the bottom part. In a closed space formed by the trough covered with the trough lid, a cable support member made of resin and/or rubber is arranged at a predetermined position in the longitudinal direction of the trough; , the leaky coaxial cable is placed with the support wire facing downward, the trough body has a substantially U-shaped cross section, and one end and the other end of the trough body and the trough lid. A connecting portion is formed in each of the troughs, and a plurality of troughs can be connected by connecting the respective connecting portions, and further, the trough body and the trough lid that are adjacent to each other are covered with each other. In a trough structure formed by connecting a predetermined number of troughs, a plurality of the cable support members are arranged at predetermined intervals in a longitudinal direction inside a closed space formed by the trough structure, In the cable support member, the leaky coaxial cable is placed on the support part formed at a predetermined height of the cable support member in any position of the cable support member, and The support part is formed in a substantially semicircular shape so that the leaky coaxial cable can be stored therein, and the leaky coaxial cable is attached to the support part of the cable support member at a predetermined height from the bottom part of the trough. The trough body is supported at a predetermined angle, and a trough fixing bolt insertion hole is provided at the bottom of the trough body, and the trough body is attached to the concrete ground by an anchor bolt inserted into the trough fixing bolt insertion hole. In the leaky coaxial cable laying structure to be fixed, a pair of downwardly projecting grooves facing each other across a groove having a predetermined length along the longitudinal direction of the trough are formed in the widthwise center of the back surface of the bottom of the trough body. A rib is formed , and the trough fixing bolt insertion hole is an elongated hole-shaped existing trough fixing bolt formed approximately in the longitudinal and widthwise center between the ribs and facing the longitudinal direction of the trough body. The trough body is attached to the concrete ground by an anchor bolt inserted through an insertion hole or an insertion hole for the trough fixing bolt that can be formed at any position in the groove between the ribs. This leaky coaxial cable laying structure is characterized in that, when being fixed, the position of the trough fixing bolt insertion hole can be adjusted to correspond to the fixing position of the anchor nut .
By adjusting the connection angle of the connection part of the trough body in at least one of the left-right direction and the vertical direction, the longitudinal direction of the trough body can be adjusted by adjusting the bolt fixing position when inserting the anchor bolt into the trough fixing bolt insertion hole. This leaky coaxial cable laying structure is characterized in that it is possible to adjust not only the distance between the formation positions but also the displacement of the fixing position in the width direction and/or the vertical direction of the trough body.
In this trough-based leaky coaxial cable installation structure, the trough has a highly rigid and linear shape, and is made of a material with superior bending elastic modulus compared to corrugated protection members, making it easy to install in a straight line. An excellent laying structure can be obtained, and as a result, an excellent aesthetic appearance can be obtained.
Furthermore, if a material with a dielectric constant of 3.15 or less is used for the resin forming the trough structure, it is possible to obtain a leaky coaxial cable installation structure with excellent communication characteristics and low transmission loss and coupling loss, as described below. .
Therefore, by using a resin containing inorganic substances for the resin used in the trough structure, it is possible to improve not only communication properties but also mechanical properties such as tensile strength, flexural modulus, and impact strength, as well as corrosion resistance and weather resistance. A leaky coaxial cable can be laid using a trough structure with excellent flame retardancy.
The characteristics of the leaky coaxial cable installation structure of the present invention are that, in order to improve the above-mentioned properties, even if the resin material contains inorganic substances, the dielectric constant can be suppressed to a predetermined value of 3.15 or less. Even when the cable is housed in a trough, it has been successfully achieved that the same communication characteristics as when it is placed exposed on concrete ground can be obtained.

The trough body has a substantially U-shaped cross section, and connecting portions are formed at one end and the other end of the trough body and the trough lid, respectively, and by connecting the respective connecting portions, It is desirable that a plurality of said troughs can be connected. At this time, the troughs can be connected at a bending angle within a range of 4° or less, which does not exceed the maximum bending angle of the leaky coaxial cable. When the leaky coaxial cable is installed at a bent part, the bent part can be bent not only in the left and right direction but also in the vertical direction, but the bending angle of the trough connection part must be 4 degrees or less. desirable.
Incidentally, the maximum bending angle of a leaky coaxial cable is said to be 5 degrees or less, but if the outer conductor is made of copper, it is desirable to have a margin of 4 degrees or less. In this case, the maximum bending angle refers to the maximum allowable bending angle when the leaky coaxial cable is restrained a predetermined distance and the cable is bent to one side. Here, if the outer conductor of the leaky coaxial cable is made of aluminum, the bending angle of the bent part of the leaky coaxial cable may be formed to be 2° or less, but not exceed the maximum bending angle of 2° in the case of an aluminum conductor. desirable.

In a trough structure formed by connecting a predetermined number of troughs each of which is covered with the trough body and the trough lid that are adjacent to each other, a trough structure is provided at a predetermined position in the longitudinal direction inside a closed space formed by the trough structure. , a plurality of the cable support members are arranged at predetermined intervals, and the cable support member is arranged at a predetermined height in the support part formed at a predetermined height of the cable support member in any position. It is desirable that a leaky coaxial cable be placed.

The support part of the cable support member is formed in a substantially semicircular shape so that the leaky coaxial cable can be accommodated, and the leaky coaxial cable is arranged at a predetermined height from the bottom of the trough in the cable support member. It is desirable to be supported at a predetermined angle. In this way, by storing the support wire covered with the outer sheath in the groove formed at a predetermined angle in the cable support member, if the leaky coaxial cable is supported at a predetermined height and at a predetermined angle, the leaky coaxial cable The slots can be oriented at a predetermined angle.

The support portions of at least some of the plurality of cable support members are formed at positions offset by a predetermined distance from the center of the cable support member in the width direction, and the leaky coaxial cable is offset from the center of the cable support member in the width direction. Continuous bent portions in the longitudinal direction of the trough structure are approximately formed alternately on the support portions of the cable support members arranged at positions offset from the center by a predetermined distance to the left and right alternately. It may be curved and loosely arranged in an S-shape. In this way, by arranging the coaxial cable to be loose in the horizontal direction in a substantially S-shape, it is possible to respond not only to temperature expansion and contraction, but also to tension changes due to earthquakes, and prevents deformation of the leaky coaxial cable. .

Here, it is preferable that the bending angle of the bent portion of the leaky coaxial cable loosely arranged in a substantially S-shape is formed to be 0.5° or more and 2° or less. In particular, when the outer conductor of the leaky coaxial cable is made of aluminum, it is desirable that the bending angle of the bent portion of the leaky coaxial cable be formed to be 2° or less, but not exceed the maximum bending angle of 2° for the aluminum conductor. . The bending angle of the leaky coaxial cable as used in the present invention is the angle formed by a straight line connecting the cross-sectional centers of the leaky coaxial cable between supporting parts supported by adjacent supporting members and the center line in the longitudinal direction of the trough body. . This is an apparent bending angle because the straight line connecting the centers of the support parts of adjacent support members coincides with the angle formed by the center line in the longitudinal direction of the trough body. The actual leaky coaxial cable is arranged in an S-shape with slack relative to this apparent bending angle. Therefore, when the apparent bending angle is 4°, the leaky coaxial cable is loosely arranged in an S-shape, so the bending angles of the maximum bending portions corresponding to both sides of the support member are each smaller than 4°. Become. It is desirable that the bending angle of the leaky coaxial cable, which is loosely arranged in a substantially S-shape, is 0.5° or less, which is a permissible bending angle of the outer conductor of the cable, of 2° or less.

The cable support members may be arranged at intervals of 1 m or more (at least the unit length of the trough) and 6 m or less of the trough structure, but the cable support members may be arranged at intervals of 2 m or more and 6 m or less. desirable. In particular, the spacing between the supporting members of the leaky coaxial cable needs to be 6 m or less in order to suppress deflection due to the cable's own weight.
The leaky coaxial cable laying structure may be such that the cable support members are linearly provided at intervals of 2 m or more and 6 m or less of the trough structure.

The cable support member may be formed integrally with the trough body made of resin. Here, the trough body may be made of resin, but is preferably made of polyolefin resin which has excellent dielectric properties and water absorption resistance. As the polyolefin resin, polyethylene, polypropylene, or a mixed resin thereof can be used. As the polyolefin resin, a recycled polyolefin resin can be used. It is desirable that the mass ratio of polyethylene and polypropylene in the recycled polyolefin resin is about 9:1. This polyolefin-based recycled resin may contain a predetermined amount of inorganic matter to improve strength, flame retardance, weather resistance, and the like. For example, the inorganic material can be contained in an amount of up to 40% by mass based on the total mass of the recycled resin containing inorganic materials, but is preferably 36% by mass or less. Here, the content of up to 36% by mass with respect to the total mass of the recycled resin is the content ratio of the inorganic matter when the total mass of the resin after containing the inorganic matter is 100% by mass.

As described above, inorganic substances such as magnesium hydroxide, calcium carbonate, and titanium oxide are added in predetermined amounts to the recycled polyolefin resin in consideration of strength, flame retardance, weather resistance, and the like. Here, for example, the mass proportion of each inorganic substance is the mass proportion of the entire polyolefin-based recycled resin material containing the inorganic substance, and 19 mass% of magnesium hydroxide, 15 mass% of calcium carbonate, and 2 mass% of titanium oxide. It is blended with a target ratio. In mass-produced products, the content of magnesium hydroxide and calcium carbonate is allowed to be approximately ±2% by mass, and the content of titanium oxide is allowed to be ±0.5% by mass. Of course, even if a large amount is blended due to variations, it is necessary to prevent the content from exceeding 40% by mass of the total mass of the recycled polyolefin resin due to impact value, cost, etc.

The cable support member is formed integrally with the trough body at a predetermined position in the longitudinal direction of the trough body made of resin, or the cable support member is formed separately from the trough body, and the cable support member is formed separately from the trough body. A fixing part is formed on the inner side of the cross section, and the cable support member is fixed to the fixing part, and the fixing part is formed so that the cable support member can be inserted into and fixed to the inner surface of the trough body. The inner ribs may be opposed to each other, and the cable support member may be inserted and fixed between the inner ribs.

In this case, it is preferable that the inner rib is not formed on the inner bottom surface of the trough, but that the inner rib is formed only on the inner surface of the trough, and further that a groove for draining water is formed in the bottom of the cable support member. This structure prevents rainwater from accumulating at the bottom of the trough.

Here, the cable support member may be made of resin or rubber, and a rubber sheet may be attached to at least the support portion of the cable support member made of resin. By doing this, when tension is applied to the leaky coaxial cable, the frictional force becomes large, and the leaky coaxial cable is less likely to shift during an earthquake or the like.

At least a portion of the leaky coaxial cable placed on the cable support member is tied to the cable support member with a string-like fixing member, so that the leaky coaxial cable is prevented from deforming in cross section. It may be fixed to the cable support member.

When the trough lid is fixed to the trough body with a fixing bolt, a pressing body made of a polyethylene foam sheet is attached to the The leaky coaxial cable placed on the cable support member is disposed above the leaky coaxial cable and presses the pressing body within a range where the cross-sectional deformation strain rate of the leaky coaxial cable is 0.2%. It may also be a fixed structure for a leaky coaxial cable that is fixed.
Further, when the trough lid is fixed to the trough body with fixing bolts, a pressing body made of a polyethylene foam sheet is provided at least in a part of the arrangement part of the cable support member on which the leaky coaxial cable is placed. , the leaky coaxial cable is disposed above the leaky coaxial cable and is placed on the cable support member by pressing the pressing body within a range where the cross-sectional deformation strain rate of the leaky coaxial cable is within a range of 0.2%. A leaky coaxial cable installation structure may be used, which is capable of fixing the cable so that the cable can be fixed with a pulling force of 300 kg or more per 100 m.

A trough fixing bolt insertion hole may be provided in the bottom of the trough body, and the trough body may be fixed to the concrete ground by an anchor bolt inserted through the trough fixing bolt insertion hole.

The existing elongated trough fixing bolt insertion hole formed in the longitudinal direction and the width direction of the trough body, or the widthwise center of the back surface of the bottom part. Mutually opposing ribs having a predetermined length are formed along the longitudinal direction of the trough, and the anchor is inserted into one of the trough fixing bolt insertion holes formed at any position in the groove between the ribs. When the trough body is fixed to the concrete ground with bolts, it may be possible to adjust the formation position of the trough fixing bolt insertion hole so as to correspond to the fixing position of the anchor bolt. In addition, the connecting part of the trough body can accommodate bends of 4 degrees or less in the horizontal and vertical directions. It becomes possible to adjust both positional deviation (angular deviation).

Between the connection parts that interconnect the leaky coaxial cables, the farther the distance from the feeding point is, the more the arrangement angle of the slots of the leaky coaxial cables increases with respect to the cable axis direction at each predetermined interval of the leaky coaxial cables. The slots may be arranged at small spacings such that the slots are large, or the slots are densely packed.

It is preferable that the connection portion that connects the leaky coaxial cables to each other is arranged at a position other than the arrangement portion of the cable support member of the trough structure.

The leaky coaxial cable is placed at a predetermined height on the cable support member made of resin inside the closed space formed by the trough structure formed by connecting the troughs in which the trough body is covered with the trough lid. The communication characteristics under the predetermined conditions in the 400 to 440 MHz band when placed at a predetermined angle are as follows: The leaky coaxial cable is placed at a predetermined height on the cable support member placed on the concrete ground without the trough structure. , it is possible to have communication characteristics in which the transmission loss is within ±2 dB/km and the coupling loss is within ±2 dB when compared with the case where the transmission loss is ±1 dB/km. It is desirable to have communication characteristics within a range of 1 km and a coupling loss within ±1 dB.

Furthermore, the leaky coaxial cable is placed at a predetermined height on the cable support member made of resin inside the closed space formed by the trough structure formed by connecting the troughs in which the trough body is covered with the trough lid. Now, as a test result of a communication characteristic confirmation test in the 400 to 440 MHz band of the trough structure when placed at a predetermined angle , the trough structure was made to absorb water by wetting the outer and inner surfaces of the trough structure with water. Even when using a structure, the same communication characteristics as when the outer and inner surfaces of the trough structure are dry can be obtained, and furthermore, the height above the concrete ground can be adjusted without the trough structure. When compared with the case where the leaky coaxial cable is placed on the cable support member at a predetermined height and at a predetermined angle, communication characteristics are such that the transmission loss is within ±2 dB/km and the coupling loss is within ±2 dB. is desirable.

It is desirable that the resin material forming the trough structure is a recycled polyolefin resin containing an inorganic substance or a polyolefin resin containing an inorganic substance.

The polyolefin recycled resin forming the trough structure has a dielectric constant of 3.15 or less at a frequency of 400 to 440 MHz measured by a capacitance method, and the trough lid and the trough body forming the trough structure It is desirable that the maximum wall thickness is 10 mm or less. In this way, when the dielectric constant and the maximum wall thickness of the trough are below the predetermined values, good communication characteristics can be obtained. The trough structure may be formed from a material having a water absorption rate of 0.15% or less after water absorption at 23° C. for 24 hours, as measured based on JIS K7209, which is equivalent to ASTM D570.

According to the first invention, the leaky coaxial cable can be laid by simply placing the leaky coaxial cable on the cable support member placed inside the trough, so other fixing members, gripping members, etc. are not required. be. In particular, since the resin trough is used, it is possible to prevent radio waves from the earth leakage coaxial cable disposed inside from being blocked. For example, by using a recycled resin trough that has high strength, high corrosion resistance, high weather resistance, and excellent flame retardancy, we can obtain a leaky coaxial cable laying structure that absorbs little radio waves and allows stable transmission and reception. I can do it. Furthermore, the leaky coaxial cable installation structure of the present invention uses a trough that is made of a material with excellent bending rigidity and has excellent straightness compared to a corrugated protection member, so the leaky coaxial cable has high rigidity and excellent straight line workability. It is possible to realize the following laying structure.

In addition, the trough structure has high rigidity and does not bend even when the environmental temperature changes, maintaining the laid state, so that, for example, it is possible to maintain the laid state substantially parallel to the railroad tracks. Furthermore, since iron angles and trough bridges are not used, there is no absorption of radio waves by the supporting members of these trough structures. Therefore, the leaky coaxial cable installation structure of the first invention is suitable for communication with high-speed railways, etc., especially when it is installed beside the railway tracks of high-speed railways.

In addition, since the leaky coaxial cable is supported by the cable support member inside the trough, the slots must always be oriented at a predetermined height and in a predetermined direction (including when they are arranged alternately facing each other) and in a predetermined position. It is possible to place it accurately. Therefore, the direction of electromagnetic waves emitted from the slot of the leaky coaxial cable can be stabilized. For example, it becomes possible to transmit and receive signals favorably between an antenna buried in a space between the outer frame of a train car body and the interior of the train, and a leaky coaxial cable. For example, it is possible to prevent the leaky coaxial cable from meandering or twisting due to the influence of reflection from the trough bottom or the curling tendency of the leaky coaxial cable, which occurs when the leaky coaxial cable is placed directly on the trough bottom.

Additionally, since the trough is sealed, it can be protected from damage and performance degradation due to leaky coaxial cable trauma, animal ingestion, and contamination. Furthermore, since the trough lid is provided, it is possible to prevent rainwater from entering the inside of the trough.

Furthermore, since the leaky coaxial cable is laid in a closed space within the trough where air pressure fluctuations are small, vibration fatigue of the cable due to repeated air pressure fluctuations when trains pass can be significantly alleviated. Therefore, by preventing the surface of the cable from deteriorating due to water wetting or UV irradiation, it is possible to stabilize the communication characteristics and extend the life of the leaky coaxial cable.

Further, by forming the connecting portions at both ends of the trough body and the trough lid, a plurality of troughs can be easily connected to form a trough structure. Note that even if a connecting portion is not formed at both ends of the trough body and the trough lid, as long as the cross-sectional shapes of both ends of at least a plurality of trough bodies are the same, the longitudinal direction of such trough bodies is It is also possible to connect both ends to each other to form a trough structure. In any case, it is possible to form a trough structure having a continuous closed space of a predetermined length.

Furthermore, since the leaky coaxial cable is supported at a predetermined distance from the bottom of the trough, even if water enters the trough, the cable can be prevented from getting wet. Therefore, adhesion of water to the leaky coaxial cable and shielding of radio waves due to this can be suppressed. Furthermore, since the leaky coaxial cable is arranged at a predetermined height inside the trough by the cable support member, it is possible to weaken the influence of reflected waves from the inside of the trough or from the concrete ground, and at the same time prevent meandering.

Furthermore, if the support portion of the cable support member is formed in a shape that allows the leaky coaxial cable to be accommodated, the leaky coaxial cable can be supported more stably. Therefore, the leaky coaxial cable can be arranged so that the electromagnetic waves transmitted from the slot of the leaky coaxial cable are at an appropriate angle with respect to the receiving antenna.

In addition, in order to remove curls and twists in the leaky coaxial cable, when laying the leaky coaxial cable, tension is applied to the leaky coaxial cable to remove some of the curls and twists mentioned above before laying the leaky coaxial cable. do. Here, by setting the installation interval of the cable support members to 6 m or less, slack in the leaky coaxial cable can be suppressed. For example, stable transmission and reception is possible by suppressing changes in the radiation direction of electromagnetic waves emitted from the slots due to slack in the leaky coaxial cable due to its own weight. In addition, due to the slackness of the leaky coaxial cable, the leaky coaxial cable does not come into contact with the bottom of the trough, which prevents the leaky coaxial cable from getting wet even if rainwater enters the trough. Damage can be protected.

Moreover, although the installation interval of the cable support members can be made to match the length of the trough and be 1 m or more, it is preferable to set it to 2 m or more. If the installation interval becomes shorter than this, although the cable can be stably supported, the number of installed cable support members will increase, resulting in higher costs. Therefore, in order to prevent the cable from loosening due to its own weight, to stably support the cable, and to avoid increasing costs, the installation interval of the cable support members needs to be 2 m or more and 6 m or less. By arranging the cable support members at intervals of 2 m or more and 6 m or less in this way, it is possible to absorb temperature expansion and contraction of the leaky coaxial cable due to environmental temperature changes.

In addition, the support parts facing the longitudinal direction of the trough, which are alternately offset from the center of the width direction of the cable support member by a predetermined distance to the left and right, are arranged in a staggered manner with respect to the longitudinal direction of the trough structure. By arranging the cable in a loose manner so as to form a continuous bend in an S-shape, it becomes possible to arrange the leaky coaxial cable in a relaxed state. For this reason, by arranging cable support members at predetermined intervals, we not only create slack in the vertical direction, but also arrange them horizontally in an S-shape, which not only helps in responding to environmental temperature changes, but also in preventing earthquakes, etc. Even when the leaky coaxial cable receives tension from the outside, the stress can be alleviated, and deformation and breakage of the leaky coaxial cable can be prevented.

The bending angle of the leaky coaxial cable in the S-shaped arrangement is preferably 0.5° or more and 2° or less. This S-shaped slack arrangement can absorb expansion and contraction of the leaky coaxial cable due to earthquakes and environmental temperature changes. At this time, the vicinity of the peaks and valleys of the leaky coaxial cable are supported by the cable support member in parallel to the tube axis direction, so that concentration of bending stress on the tops of the peaks and valleys can be avoided. In the case of an S-shaped arrangement, the installation spacing of the cable support members is such that the bending is stably applied to the leaky coaxial cable at a small bending angle such as 0.5°, and the cable support members are spaced so as to stably bend the leaky coaxial cable at a small bending angle such as 0.5°. In order to avoid localized stress concentration, the length needs to be 2 m or more, but by making it 6 m or less, the influence of slack due to its own weight can be eliminated. Therefore, in order to perform stable bending for an S-shaped arrangement and eliminate the influence of slack due to its own weight, the arrangement interval of cable support members is preferably 2 m or more and 6 m or less. The bending angle of the coaxial cable can be adjusted as appropriate within the range of 0.5° or more and 2° or less. At this time, the amount of offset of the cable support member can be adjusted as appropriate depending on the arrangement interval and bending angle of the cables.

The cable support member and the trough lid may be made of resin, and the cable support member may be formed integrally with or separately from the trough body, which is made of resin. If the trough body and the cable support member are integrally formed, there is no need to fix the cable support member to the trough body. As the resin used for the trough body and the trough lid, it is desirable to use a polyolefin resin that is hydrophobic and has a low water absorption rate. Further, as the polyolefin resin, it is desirable to use a recycled polyolefin resin in consideration of environmental considerations and cost reduction. Even if recycled polyolefin resin is used, it can be used as a trough structural member and the telecommunication properties can be satisfied.

On the other hand, when the trough body and the cable support member are provided separately, it is necessary to fix the cable support member at a predetermined position on the bottom of the trough body. In this case, by forming a fixing part inside the cross-section of the trough body and fixing the cable support member to the fixing part, the cable support member can be reliably placed at a predetermined position, and the cable can be easily connected. A support member can be secured to the trough body.

For example, by forming mutually opposing inner ribs on the inner surface of the trough body to serve as a fixing part, and arranging the cable support member between these inner ribs, the cable support member can be easily fixed to the trough body. can. Therefore, the cable support member can be fixed at a predetermined position on the trough body without requiring a separate fixing bolt or the like.

Further, the cable support members formed by arranging the support portions of the cable support members offset from the center of the cross section of the cable support member are arranged such that the offset positions are alternately offset from the center of the cross section of the trough structure in the longitudinal direction of the trough structure. By inverting the leaky coaxial cable and arranging it at predetermined intervals on the inner rib, it is possible to offset the leaky coaxial cable at a predetermined period in the trough length direction. The bending angle of the leaky coaxial cable in the S-shaped arrangement of the leaky coaxial cable in the cable support member is preferably 2° or less, and if it is 0.5° or less, the bending angle is too small to be expected to be effective. It is desirable that the angle is 0.5° or more and 2° or less. Further, in the case of an S-shaped arrangement, tension may be applied to the leaky coaxial cable as necessary in order to adjust the extra length of the S-shaped arrangement.

Further, by fixing the leaky coaxial cable to the cable support member using the string-like fixing member, it is possible to suppress the leaky coaxial cable from shifting from the support portion of the cable support member during an earthquake or the like. Further, by increasing the tightening force of the string-like fixing member that fixes the leaky coaxial cable, the leaky coaxial cable can be stably fixed. Here, the tightening force of the string-like fixing member is preferably within a range that does not cause cross-sectional deformation of the leaky coaxial cable. Furthermore, when the leaky coaxial cable, which will be described later, is not pressed by a pressing body, the tightening force of the string-like fixing member can be applied within a range where the cross-sectional deformation strain rate of the leaky coaxial cable is 0.2%.
At this time, the reason why it is necessary to set a restriction so that the tightening force of the string-like fixing member is applied within a range where the cross-sectional deformation strain rate of the leaky coaxial cable is 0.2% is as follows. In each cross section of the resin insulator string provided on the outer periphery of the inner conductor, the insulator string is wound spirally around the outer periphery of the inner conductor so as to face toward the center, and inside the cable, the inner conductor is It has a cross-sectional structure in which a hollow portion is formed. For this reason, the rigidity of the cross section of the cable is lower than that of a normal power cable in which the entire outer periphery of the conductor is coated with an insulator.

Further, by pressing the leaky coaxial cable with the pressing body, a pressing force can be applied to the leaky coaxial cable within a range where the cross-sectional deformation strain rate of the leaky coaxial cable is 0.2%. Therefore, due to the contact between the leaky coaxial cable and the pressing body, frictional force can be applied to the leaky coaxial cable, increasing the resistance to expansion and contraction in the cable axial direction due to thermal expansion and contraction of the leaky coaxial cable and the resistance to pulling it out from the outside. be able to. As a result, it becomes difficult to suppress expansion and contraction in the cable axial direction due to thermal expansion and contraction of the leaky coaxial cable, and furthermore, it becomes difficult to pull out the leaky coaxial cable in one direction from inside the trough. Therefore, it is possible to reduce the dimensional change of the leaky coaxial cable due to thermal expansion, and to prevent the leaky coaxial cable from being stolen. In this way, by applying the cross-sectional deformation strain rate of the leaky coaxial cable within the range of 0.2%, it is possible to prevent creep deformation of the cross-section of the leaky coaxial cable due to pressure. Thereby, deformation of the cross section of the cable and dimensional change in the longitudinal direction of the cable axis can be suppressed, and at the same time, long-term durability of the cable itself can be maintained. Furthermore, even if the cross-sectional deformation strain of the leaky coaxial cable is suppressed within a predetermined range when a pull-out force is applied to the leaky coaxial cable, the cable pull-out force per predetermined length, for example, 100 m of cable length, must be 300 kg or more. It is possible to obtain an anti-theft effect.

Furthermore, by fixing the trough body to the concrete ground with anchor bolts, the trough body is directly fixed to the concrete ground, so the trough body will not move even in the event of an earthquake. Further, even in this case, the top of the anchor bolt and the bottom of the leaky coaxial cable are arranged a predetermined distance apart, so that there is no interference between the two. Furthermore, there is no need to separately arrange support members, angle members, etc. for fixing the trough. Furthermore, since an angle member or the like is not used as a support member for fixing the trough, the influence of electromagnetic waves due to the angle member or the like can be suppressed.

Here, the trough fixing bolt insertion hole may be an existing insertion hole in the form of an elongated hole formed approximately at the center of the trough body in the longitudinal direction and the width direction, and facing in the longitudinal direction of the trough body. A trough fixing bolt insertion hole may be formed between mutually opposing ribs having a predetermined length along the longitudinal direction. When a rib is used, the rib can function as a guide when forming the fixing bolt insertion hole. By doing this, even if there is an error in the formation position of the anchor nut placed on the concrete ground, the formation position of the trough fixing bolt insertion hole has a degree of freedom along the rib, so the trough can be fixed. There is no problem. Here, even if the formation position of the anchor nut placed in the concrete ground is shifted in the width direction of the trough body, the connection angle of the connection part of the trough body can be adjusted within 4 degrees. Therefore, the deviation in the formation position of the anchor nut can be accommodated by adjusting the connection angle of the connection part of the trough body.

In addition, in the leaky coaxial cable, the amount of leakage of radio waves (coupling loss) can be controlled by designing the slots. Taking advantage of this characteristic, for example, by using a leaky coaxial cable designed such that the arrangement angle and density of slots increase at each predetermined interval of the leaky coaxial cable as it approaches the termination point, it is possible to As the distance increases, the coupling loss decreases and the amount of radio wave leakage increases. Therefore, compared to using a leaky coaxial cable with a constant coupling loss from the feeding point to a position far from the feeding point, the relay interval can be made larger, and the width of the reception level can be made wider.

Additionally, by arranging the cable connection part that connects the leaky coaxial cables to each other in a position other than the location of the cable support member in the trough structure, interference between the cable connection part and the cable support member can be avoided. .

Further, a leaky coaxial cable is placed at a predetermined height and at a predetermined angle on a cable support member inside a closed space inside a trough structure formed by connecting the troughs in which the trough body is covered with the trough lid. The communication characteristics under specified conditions in the 400 to 440 MHz band are as follows: When a leaky coaxial cable is placed at a specified height and angle on a cable support member placed on concrete ground without a trough structure, When compared with the above, it is possible to obtain a leaky coaxial cable installation structure that satisfies communication characteristics with a transmission loss within ±1 dB/km and a coupling loss within ±1 dB. Therefore, it is possible to satisfy communication characteristics in which the transmission loss is within ±2 dB/km and the coupling loss is within ±2 dB.

Furthermore, even when using a structure in which the outer and inner surfaces of the trough structure are wetted with water to absorb water, it is possible to obtain the same communication characteristics as when the outer and inner surfaces of the trough structure are dry. can. In other words, when compared to placing a leaky coaxial cable at a predetermined angle at a predetermined height on a cable support member whose height is adjusted on concrete ground without the presence of a trough structure, the transmission loss is ±1 dB/km. It is possible to obtain a leaky coaxial cable installation structure having communication characteristics in which the coupling loss is within ±1 dB. Therefore, even in this case, it is possible to satisfy the communication characteristics within the range of transmission loss within ±2 dB/km and coupling loss within ±2 dB.

In this way, there are cases in which the leaky coaxial cable is placed at a predetermined height on the cable support member inside the closed space of the resin trough structure, and cases in which the leaky coaxial cable is not placed inside the trough structure. In comparison with the case where a leaky coaxial cable is placed at a predetermined height on a cable support member on concrete ground, the transmission loss is within ±1 dB/km and the coupling loss is within ±1 dB in the above communication characteristic evaluation test. In order to satisfy the communication characteristics in the range of , it is possible to satisfy the communication characteristics in the range of transmission loss within ±2 dB/km and coupling loss within ±2 dB. Furthermore, when comparing the communication characteristics when water is absorbed from the surface of a resin trough structure and when it is placed inside a dry resin trough structure, even though it contains inorganic substances, It can be seen that the communication characteristics remain unchanged.

Although a trough structure made of recycled polyolefin resin was used as a leaky coaxial cable laying structure of a trough structure that satisfies communication characteristics, a leaky coaxial cable laying structure using polyolefin resin may also be used. By using a polyolefin-based recycled resin trough structure, it is possible to satisfy communication characteristics with a transmission loss within ±1 dB/km and a coupling loss within ±1 dB. Therefore, it is possible to satisfy communication characteristics in which the transmission loss is within ±2 dB/km and the coupling loss is within ±2 dB. The reason for this is thought to be that the recycled polyolefin resin is hydrophobic and has an extremely low water absorption rate.

In addition, the dielectric constant of the recycled polyolefin resin that forms the trough structure is 3.15 or less at a frequency of 400 to 440 MHz measured by the capacitance method, and the maximum wall of the trough lid and trough body that make up the trough body is 3.15 or less. If the thickness is 10 mm or less, a leaky coaxial cable installation structure with excellent communication characteristics with the leaky coaxial cable inside the trough body can be obtained.

A second invention provides a trough body made of resin having a bottom portion and side walls standing up on both sides of the bottom portion, and having a substantially U-shaped cross section; A connecting portion is formed at each end of the trough, and a plurality of troughs can be connected by connecting the respective connecting portions, and a trough is formed in which the trough body is covered with the trough lid. In the closed space, a cable support member is arranged at a predetermined position in the longitudinal direction of the trough, and a leaky coaxial cable can be placed on the support part of the cable support member, and the leaky coaxial cable is placed on the bottom part of the trough body. In the trough body for storing the leaky coaxial cable, the trough body is provided with a trough fixing bolt insertion hole, and the trough body is fixed to the concrete ground by an anchor bolt inserted into the trough fixing bolt insertion hole. A pair of ribs protruding downward and facing each other across a groove having a predetermined length along the longitudinal direction of the trough is formed in the widthwise center of the back surface of the bottom of the main body, and the trough fixing bolt insertion hole is the existing elongated trough fixing bolt insertion hole formed approximately at the center of the longitudinal direction and the width direction between the ribs and facing the longitudinal direction of the trough body, or any groove between the ribs. The fixing position of the anchor nut when the trough body is fixed to the concrete ground by the anchor bolt inserted through any one of the trough fixing bolt insertion holes that can be formed at the position of A trough body for housing a leaky coaxial cable, characterized in that the formation position of the trough fixing bolt insertion hole can be adjusted to correspond to the above.
By adjusting the connection angle of the connection part of the trough body in at least one of the left-right direction and the vertical direction, the longitudinal direction of the trough body is adjusted by adjusting the bolt fixing position when inserting the anchor bolt into the trough fixing bolt insertion hole. The trough body may accommodate a leaky coaxial cable that can adjust both the widthwise and/or vertically fixed position displacement of the trough body in addition to adjusting the distance between the formation positions.

Further, as a fixing part for fixing the cable support member inside the cross section of the trough body, the cable support member can be inserted into the inner surface of the trough body and fixed at a predetermined position in the longitudinal direction of the trough body. Inner ribs may be formed so as to face each other. At this time, it is desirable that an inner rib be formed only on the inner surface of the trough, and further that a groove for draining water be formed at the bottom of the cable support member. This structure prevents rainwater from accumulating at the bottom of the trough.
The cable support member is formed integrally with the trough body at a predetermined position in the longitudinal direction inside the cross section of the trough body, or the cable support member is inserted into and fixed to the inner surface of the trough body. The trough body for accommodating any leaky coaxial cable may be formed with inner ribs facing each other.
By providing an anchor nut insertion hole instead of providing the trough fixing bolt insertion hole at either position of the existing trough fixing bolt insertion hole of the trough body and the groove between the pair of ribs, It may be a trough body that houses a leaky coaxial cable and has a structure that can be fixed with anchor bolts provided in the concrete ground.

Alternatively, the cable support member for supporting the leaky coaxial cable may be formed integrally with the trough body at a predetermined position in the longitudinal direction of the trough body, inside the cross section of the trough body.

The trough body is covered with the trough lid made of resin, connection portions are formed at one end and the other end of the trough body and the trough lid, respectively, and the trough lid is covered with the trough body. The trough bodies covered with a plurality of trough lids may be connectable by connecting the respective connecting portions in a state where the trough bodies are covered with a plurality of trough lids.

It is preferable that the trough body is formed of a polyolefin resin material containing an inorganic substance, and that the dielectric constant of the trough body in the 400 to 440 MHz band measured by a capacitance method is 3.15 or less. When polyolefin resin contains inorganic substances, its dielectric properties deteriorate, so it is necessary to check whether the content of inorganic substances is within an allowable range. Here, the dielectric constant of polyethylene in the 400-440 MHz band measured by capacitance method is 2.35, that of polypropylene is 2.65, but the dielectric constant of recycled polyolefin resin is 3.35. By satisfying the dielectric constant of 15 or less and containing an inorganic substance, the dielectric constant increases, but does not increase to an extreme degree.

The trough body has mechanical properties such as a tensile strength of 20 MPa or more, a flexural modulus of 1000 MPa or more, and a Charpy impact value of 5 kJ/m ² or more as measured by a Charpy impact test based on JIS K7111 . Furthermore, the tensile strength of the resin forming the trough body after an accelerated weather resistance test of irradiating ultraviolet light with an irradiation intensity of 90 mW/cm ² for 2000 hours in an environment of 50% humidity. The residual rate is 95% or more of the tensile strength before irradiation with ultraviolet light, and the residual rate of Charpy impact value after irradiation with ultraviolet light is 90% or more of the Charpy impact value before irradiation with ultraviolet light. may be formed.

The trough body has a water absorption rate of 0.15% or less after water absorption at 23°C for 24 hours, as measured based on JISK7209, which is equivalent to ASTM D570 , and is further immersed at room temperature for 24 hours in accordance with JISK7114. In the test, an immersion test was conducted with a 3% NaCl aqueous solution as a seawater simulating liquid, a 30% CaCl ₂ immersion test as a snow melting agent simulating liquid, and a 2:1 ratio of H ₂ SO ₄ and HNO ₃ as an acid rain simulating liquid. In all tests, the mass change rate of the resin forming the trough body was 0.1% or less in an immersion test using a test solution obtained by diluting the mixed liquid to a concentration of 1%. Good too.

By forming the trough body from a material having a dielectric constant of 3.15 or less in the 400 to 440 MHz band, good communication characteristics can be ensured. Furthermore, the tensile strength of the trough body is 20 MPa or more and the bending elastic modulus is 1000 MPa or more, so that the material strength required for the trough body is satisfied, and the Charpy impact value is 5 kJ/m ² or more. , it can satisfy practically sufficient mechanical properties.

Although the leaky coaxial cable trough body and the trough lid can be formed using polyolefin resin, it is preferable to form them using polyolefin-based recycled resin. For example, by forming the trough body from recycled polyolefin resin, it not only satisfies the strength required for practical use, but also corrosion resistance confirmation tests such as seawater simulation tests, snow melting agent simulation tests, acid rain simulation tests, and weather resistance acceleration tests. It also shows excellent corrosion resistance and weather resistance. This makes it possible to be environmentally friendly and reduce costs, while at the same time ensuring the long-term durability of the trough. In addition, in paragraphs 0081 and 0082 , the tensile strength, flexural modulus, Charpy impact value, water absorption, corrosion resistance, weather resistance, etc. of the trough body were described , but the trough lid is also made of the same polyolefin as the trough body. If recycled materials are used, similar properties such as tensile strength, flexural modulus, Charpy impact value, water absorption, corrosion resistance, and weather resistance can be obtained. A similar invention can be obtained regarding the characteristics of the trough lid.

Furthermore, as will be described later, when using a trough structure formed using recycled polyolefin resin with a dielectric constant of 3.15 or less, transmission loss, Both coupling loss and properties should be approximately the same as when placed directly on concrete ground without using a resin trough, and the difference in average values of transmission loss and coupling loss should be within ±1 dB/km and ±1 dB or less, respectively. I can do it. Therefore, it is possible to satisfy communication characteristics in which transmission loss and coupling loss are within ±2 dB/km and within ±2 dB, respectively. Further, as described above, since the water absorption rate of the trough body and the trough lid constituting the trough structure is low, stable communication characteristics can be obtained even if the trough body gets wet with rainwater or the like. Therefore, in addition to the dielectric constant of the material forming the trough, the water absorption rate of the material forming the trough structure is an important characteristic in maintaining telecommunication characteristics.

A third invention is a polyolefin-based recycled resin material containing an inorganic substance, which contains at least magnesium hydroxide and titanium oxide as the inorganic substance, and has a dielectric constant of 3.15 or less, and further has a content of magnesium hydroxide in the polyolefin-based recycled resin material. This is a polyolefin-based recycled resin material with excellent flame retardancy and communication properties, characterized by a content of 18% by mass or more based on the total mass of the recycled resin material.

Here, in the present invention, since transmission and reception are performed from a leaky coaxial cable placed in the trough, a polyolefin resin material having a predetermined dielectric constant is required to ensure flame retardancy and telecommunication characteristics. Therefore, there is a need for polyolefin resins containing inorganic substances that have flame retardancy and telecommunication properties. In order to ensure flame retardancy and weather resistance to polyolefin resin, magnesium hydroxide is added as a flame retardant and titanium oxide as an ultraviolet absorber. It is possible to obtain a polyolefin-based recycled resin containing an inorganic material whose dielectric constant increase is suppressed to 3.15 or less, which is a predetermined value or less. Furthermore, by using this material, it is possible to obtain a polyolefin-based recycled resin material that not only has flame retardancy and weather resistance, but also prevents deterioration of telecommunication properties and impact properties due to increased content of inorganic substances. can.

There are three types of polyolefin-based recycled resin materials containing the inorganic substance: magnesium hydroxide, calcium carbonate, and titanium oxide, and the content ratio of each of them to the total mass of the inorganic polyolefin-based recycled resin material is 18 to 21.3 magnesium hydroxide. mass%, calcium carbonate 14 to 16.5 mass%, titanium oxide 2 to 2.2 mass%, and the total content of the inorganic substances is 34 mass% or more of the total mass of the polyolefin-based recycled resin 40 It is desirable that it is less than % by mass.

By having the above composition, it is possible to keep the dielectric constant below a predetermined value and improve the balance of water absorption, corrosion resistance, flame retardance, and weather resistance without reducing strength or impact properties. I can do it. In particular, by mixing magnesium hydroxide, calcium carbonate, and titanium oxide in the above amounts, the dielectric constant, flame retardance, and weather resistance can be optimized.

In the polyolefin recycled resin material, a virgin resin may be used as the polyolefin resin instead of the polyolefin recycled resin. Even in the case of virgin materials, if the composition is similar, similar telecommunication properties and mechanical properties can be obtained.

The polyolefin-based recycled resin material may be a material for a structure or member for telecommunications.

Since the polyolefin-based recycled resin material can have a dielectric constant below a predetermined value, it can obtain good telecommunication properties, and also has a predetermined strength, so it is suitable for use in telecommunication structures and components. can be used.

Specifically, polyolefin-based recycled resin materials have excellent flame retardancy and at the same time have a dielectric constant of 3.15 or less, thereby achieving good telecommunication properties. Furthermore, since it has a predetermined strength, for example, a tensile strength of 20 MPa or more, it is suitable for use in structures and members for telecommunications.

A fourth invention is a method of using a recycled polyolefin resin, characterized in that the recycled polyolefin resin material according to the third invention is used for a trough structure.

As described above, the polyolefin-based recycled resin material can be used for structures and members for telecommunications, and therefore can be used for the trough body and trough lid that accommodate leaky coaxial cables. Therefore, it is possible to provide a method for using a recycled polyolefin resin material for a trough structure.

A fifth invention is a method for laying a leaky coaxial cable, in which a resin trough body having a bottom and side walls standing up on both sides of the bottom and having a substantially U-shaped cross section is fixed to concrete ground. and arranging a cable support member inside the trough body, and arranging a leaky coaxial cable in the support portion of the cable support member with the support wire facing downward, In the fixing step, a pair of mutually opposing ribs having a predetermined length along the longitudinal direction is formed at the center of the bottom back surface of the trough body in the width direction, and the trough body is fixed between the ribs. An existing long hole-shaped trough fixing bolt insertion hole formed in the longitudinal direction of the trough body approximately in the center of the longitudinal direction and the width direction, or an arbitrary groove between the pair of ribs on the back surface of the bottom part. When fixing the trough to the concrete ground by inserting an anchor bolt into one of the other insertion holes formed at the position , the trough is fixed by adjusting the formation position of the bolt insertion hole for fixing the trough. This is a method for laying a leaky coaxial cable, which is characterized in that it is possible to install a leaky coaxial cable.

In addition, in the step of fixing the trough body to the concrete ground, connecting portions are formed at one end and the other end of the trough body, and each of the connecting portions is connected in a horizontal direction and/or a vertical direction. A leaky coaxial cable installation method may be used in which the leaky coaxial cable can be installed by connecting the cables at a predetermined angle so as to absorb the displacement of the formation position of the anchor nut provided in the concrete ground. By doing this, even if the formation position of the anchor nut placed in the concrete ground shifts in the width direction of the trough body, by adjusting the connection angle of the trough connection part, the formation position of the anchor nut can be adjusted in the longitudinal direction. It is possible to deal with not only positional deviations in the width direction but also widthwise positional deviations.

In the step of arranging the cable support member inside the trough body and arranging the leaky coaxial cable in the support portion of the cable support member with the support wire facing downward, the cable support member A support portion of the member is formed at the center of the cable support member, and the cable support member is provided at predetermined intervals at predetermined positions in the longitudinal direction of a trough structure in which a plurality of troughs are connected, thereby preventing the leakage coaxial cable. The method for laying a leaky coaxial cable may include the step of arranging the leaky coaxial cable in a straight line on a support portion on the cable support member.
In the step of arranging the cable support member inside the trough body and arranging the leaky coaxial cable in the support portion of the cable support member with the support wire facing downward, the cable support member The support portion of the member is formed offset by a predetermined distance from the center of the cable support member, and the adjacent cable support members are alternately arranged inverted, so that the leaky coaxial cable is separated from the support portion on the cable support member. The method for laying a leaky coaxial cable may include the step of arranging the leaky coaxial cable in a substantially S-shape.

By alternately arranging the cable support members offset by a predetermined distance, the leaky coaxial cable may be arranged in a substantially S-shape. In this way, by making it possible to arrange the leaky coaxial cable in an S-shape on the cable support member, the stress applied to the cable during an earthquake or the like can be alleviated and the leaky coaxial cable can be prevented from being deformed.
In the step of fixing to the concrete ground, an anchor nut insertion hole is provided in the bottom of the trough body instead of a trough fixing bolt insertion hole, and an anchor bolt is provided in the concrete ground for laying a leaky coaxial cable. It may be a method .

Furthermore, by arranging a resin trough lid on the upper part of the trough body and closing the trough, at least a part of the support part of the cable support member on which the leaky coaxial cable is placed is made of polyethylene foam sheet or rubber molding. The method may include a step of pressing the leaky coaxial cable with a pressing body made of any one of the following. By applying the pressing force at this time within the range of the cross-sectional deformation strain rate of the leaky coaxial cable of 0.2%, the cable position will not shift unless a pulling force of 300 kg or more is applied per 100 m of the leaky coaxial cable. A method of laying a leaky coaxial cable can be provided. This makes it possible to provide a laying method that is effective not only for preventing expansion and contraction due to environmental temperature changes, but also for preventing cable theft.

According to the fifth invention, the leaky coaxial cable can be laid simply by placing the leaky coaxial cable on the cable support member placed inside the trough body, so other fixing members, gripping members, etc. are unnecessary. Therefore, leaky coaxial cables can be easily installed.

In particular, by pressing the leaky coaxial cable with a pressing body when closing the trough lid, it is possible to apply a pressing force to the leaky coaxial cable, which reduces the resistance to expansion and contraction in the cable axial direction due to thermal expansion and contraction of the leaky coaxial cable, and reduces the external It is possible to increase the pulling resistance from the As a result, expansion and contraction in the axial direction of the cable can be alleviated, and it can be made difficult to pull out the leaky coaxial cable in one direction from inside the trough.

A sixth invention is a leaky coaxial cable installation structure according to the first invention, in which the resin material containing an inorganic substance constituting the trough structure is recycled polyolefin having a dielectric constant of 3.15 or less in the frequency band of 400 to 440 MHz. The polyolefin recycled resin has a tensile strength of 20 MPa or more, a flexural modulus of 1000 MPa or more, and a Charpy impact value of 5 kJ/m ² or more as measured by a Charpy impact test based on JIS K7111 . The material has a dielectric constant of 3.15 or less, a maximum wall thickness of 10 mm or less, and a water absorption rate of 0.15% or less after water absorption at 23°C for 24 hours based on JIS K7209. A half-wavelength signal installed at a height of 1.5 m directly above the leaky coaxial cable in the 400 MHz frequency band between the leaky coaxial cable placed inside the trough structure and the antenna on the train car. When communicating using a network analyzer or a spectrum analyzer using a dipole antenna, the trough surface is dry or the outer and inner surfaces of the trough are wetted with water and absorbed. The transmission loss is within ±2 dB/km in comparison with the case where the leaky coaxial cable is placed at a predetermined height and at a predetermined angle on the cable support member whose height is adjusted on concrete ground without using a trough structure. This is a communication method using a leaky coaxial cable installation structure, which is characterized in that it is possible to obtain communication characteristics in which the coupling loss is within ±2 dB.

The polyolefin-based recycled resin containing inorganic substances has good communication properties, so it can be used between a leaky coaxial cable placed inside a trough structure placed approximately parallel to the train track and an antenna on a train car. It can be expected that good communication conditions can be ensured.

In comparison with the case where the leaky coaxial cable is placed at a predetermined height and at a predetermined angle on the cable support member whose height is adjusted on concrete ground without using the trough structure, the transmission loss is ±2 dB/km. It is desirable to be able to obtain communication characteristics in which the coupling loss is within ±2 dB.

A seventh invention uses the leaky coaxial cable laying structure according to the first invention, and a resin material containing an inorganic substance constituting the trough structure in the leaky coaxial cable laying structure has a dielectric constant in a frequency band of 400 to 440 MHz. is 3.15 or less, the polyolefin recycled resin has a tensile strength of 20 MPa or more, a flexural modulus of 1000 MPa or more, and at the same time a Charpy impact test based on JIS K7111 . It has the property that the value is 5 kJ/ ^m2 or more, the dielectric constant satisfies the above-mentioned dielectric constant of 3.15 or less, and the maximum wall thickness is 10 mm or less, and after water absorption at 23°C for 24 hours based on JIS K7209. 1.5 m directly above the leaky coaxial cable in the 400 MHz frequency band between the leaky coaxial cable placed inside the trough structure with a water absorption rate of 0.15% or less and the train vehicle antenna. When communicating using a network analyzer or spectrum analyzer using a half-wavelength dipole antenna installed at a height of Comparison with the case where the leaky coaxial cable is placed at a predetermined height and at a predetermined angle on the cable support member whose height is adjusted on the concrete ground without using the trough structure. This is a communication system using a leaky coaxial cable installation structure characterized in that it is possible to obtain communication characteristics in which transmission loss is within ±2 dB/km and coupling loss is within ±2 dB.

In comparison with the case where the leaky coaxial cable is placed at a predetermined height and at a predetermined angle on the cable support member whose height is adjusted on concrete ground without using the trough structure, the transmission loss is ±2 dB/km. It is desirable to be able to obtain communication characteristics in which the coupling loss is within ±2 dB.

In addition, by forming the maximum wall thickness of the trough cover and trough body that constitute the trough structure used in the leaky coaxial cable laying structure to be 10 mm or less, the dielectric constant is lower than that of a concrete trough. Both the maximum thickness of the wall of the trough structure and the maximum thickness of the wall of the trough structure can be kept low, and good communication characteristics can be obtained between the leaky coaxial cable inside the trough structure and the on-board antenna on the train.

In addition, if the resin material constituting the trough structure in the leaky coaxial cable installation structure is a recycled polyolefin resin containing an inorganic substance with a dielectric constant of 3.15 or less in the frequency band of 400 to 440 MHz, it may be mounted inside the trough structure. Communication can be performed in the 400 MHz frequency band between the installed leaky coaxial cable and the on-board antenna of the train. At this time, since the trough structure has a predetermined tensile strength of 20 MPa or more and a bending elastic modulus of 1000 MPa or more, it goes without saying that it satisfies the strength required for the members constituting the communication system.

According to the present invention, it is possible to maintain the height and direction of the slot constant, and it is also possible to suppress the effects of wind from trains, water, pollution, etc. A leaky coaxial cable laying structure that does not exceed the maximum bending radius of the leaky coaxial cable, a method for laying the leaky coaxial cable, and a communication method using the leaky coaxial cable laying structure, which can alleviate cable deterioration due to irradiation. In addition, a communication system can be realized. In particular, since a leaky cable trough structure with a dielectric constant below a predetermined value has been achieved, good communication with an on-vehicle antenna can be performed using the above communication method and communication system. Furthermore, the leaky coaxial cable installation structure of the present invention uses a trough that is made of a material with excellent bending rigidity and has excellent straightness compared to a corrugated protection member, so the leaky coaxial cable has high rigidity and excellent straight line workability. It is possible to realize the following laying structure.

1 is an exploded perspective view showing a leaky coaxial cable installation structure 1. FIG. 1 is an assembled perspective view showing a leaky coaxial cable installation structure 1. FIG. FIG. 2 is an assembled perspective view showing a leaky coaxial cable installation structure 1a. FIG. 5 is a perspective view showing a leaky coaxial cable 5; FIG. 5 is a cross-sectional view showing a leaky coaxial cable 5. FIG. FIG. 5 is a conceptual diagram showing the arrangement of slots 23 of the leaky coaxial cable 5, etc. FIG. 3 is a perspective view of the cable support member 11. FIG. 5 is a diagram showing a process of arranging the leaky coaxial cable 5 on the cable support member 11. FIG. 3 is a cross-sectional view of the trough body 3a. An enlarged view of part B in FIG. 7A. A sectional view showing a trough fixing bolt insertion hole 41. FIG. 3 is a diagram showing a state in which the trough body 3a is fixed to the concrete ground 35 with anchor bolts 43. FIG. 3 is a plan view of the trough body 3a. FIG. 3 is a bottom view of the trough body 3a. The figure which shows the process of arrange|positioning the cable support member 11 in the trough main body 3a. The figure which shows the state where the cable support member 11 is arrange|positioned to the trough main body 3a. FIG. 7 is a partial plan view of a trough body 3a according to another embodiment. 10A is a sectional view of a trough body 3a according to another embodiment, and is a sectional view taken along line FF in FIG. 10A. FIG. 1 is a sectional view showing a leaky coaxial cable installation structure 1; FIG. 3 is a sectional view showing a leaky coaxial cable installation structure 1b. An example of a conceptual plan view of a leaky coaxial cable installation structure 1. A perspective view of the cable support member 11a. FIG. 3 is a front view of the cable support member 11a. An example of a conceptual plan view of a leaky coaxial cable installation structure 1c. A perspective view of the cable support member 11b. The figure which shows the state where the leaky coaxial cable 5 is arrange|positioned to the cable support member 11b. FIG. 7 is a front view showing the state of the leaky coaxial cable laying structure 1d before closing the trough lid 3b. FIG. 3 is a front view showing a leaky coaxial cable installation structure 1d. FIG. 7 is a front view showing the leaky coaxial cable laying structure 1e in a state before the trough lid 3b is closed. FIG. 3 is a front view showing a leaky coaxial cable installation structure 1e.

[First embodiment]
A first embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is an exploded perspective view showing a leaky coaxial cable installation structure 1 according to the present invention, and FIG. 2 is an assembled perspective view showing the leaky coaxial cable installation structure 1.

The trough 3 for a leaky coaxial cable mainly consists of a trough body 3a and a trough lid 3b. The trough body 3a and the trough lid 3b are made of resin and are molded by press molding or injection molding. As the material for the trough body 3a and the trough lid 3b, for example, recycled resin with high strength, high corrosion resistance, and high weather resistance (for example, a resin composition made of polyethylene, polypropylene, etc., and a flame retardant material, etc.) can be used. . The trough body 3a and the trough lid 3b usually have a length of about 1 m. Strictly speaking, the lengths of the trough body 3a and the trough lid 3b are set to be slightly longer than 1 m, and even if adjacent troughs 3 are connected, the length will be approximately 1 m if the overlapping length is subtracted at the time of connection. good.

Connection portions 13a and 13b are provided at one end and the other end in the longitudinal direction of the trough body 3a and the trough lid 3b, respectively. The connecting portion 13a has a groove on the inner surface of the trough body 3a, and the connecting portion 13b has a protrusion corresponding to the groove on the outer surface of the trough body 3a. Therefore, the troughs 3 can be connected to each other by connecting the connecting portion 13a of one trough body 3a and the connecting portion 13b of another adjacent trough body 3a to each other.

Note that, as in the leaky coaxial cable laying structure 1a shown in FIG. 3, the trough 3 does not need to have a connecting portion at at least one end. When arranging a plurality of such troughs in succession, a predetermined number of mutually adjacent troughs 3 may be connected. Note that a structure in which a plurality of troughs 3 each having a trough body 3a and a trough lid 3b are connected together is referred to as a trough structure. In the following description, the leaky coaxial cable laying structure 1 having the connecting portions 13a and 13b will be described, but the same applies to the leaky coaxial cable laying structure 1a.

The trough main body 3a is composed of a bottom portion 7 and side wall portions 9 that stand up on both sides of the bottom portion 7 at a substantially right angle. That is, the trough body 3a has a substantially U-shaped cross section. Fixing metal fittings 15 are attached to the upper part of the side wall portion 9 near both ends of the trough body 3a. A nut is fixed to the fixture 15.

On the other hand, the trough lid 3b is arranged on the trough body 3a and closes the upper part of the trough body 3a. A bolt insertion hole is provided at a predetermined position of the trough lid 3b, and by closing the trough lid 3b and screwing the bolt 17 into the fixing fitting 15 from above the trough lid 3b, the trough lid 3b is attached to the trough body 3a. can be fixed to. Although the fixing of the trough lid 3b and the trough main body 3a is not limited to this embodiment, it is better to have fewer parts of the trough lid 3b covered with metal parts such as fixing fittings.

A leaky coaxial cable 5 is housed inside the trough body 3a. The structure of the leaky coaxial cable 5 will be explained below. 4A is a perspective view showing the leaky coaxial cable 5, and FIG. 4B is a sectional view showing the leaky coaxial cable 5. The leaky coaxial cable 5 mainly includes, in order from the inside, an inner conductor 19, an insulator 21 including an insulator string 21a, an outer conductor 25, a slot 23 provided in the outer conductor 25, an outer sheath 27, a support wire 29, etc. configured.

The internal conductor 19 is made of aluminum or copper, for example, and can be shaped like a hollow pipe as shown. An insulator 21 including a spiral insulator string 21a is arranged around the outer periphery of the internal conductor 19. The insulator 21 is formed over substantially the entire length of the internal conductor 19. The insulator 21 is formed of a resin having stable and good insulation properties, such as polyethylene resin or fluororesin. Note that instead of the insulator 21 including the insulator string 21a, a solid resin, a foamed resin, or a resin sheet member wound spirally in the cable axial direction may be used.

An outer conductor 25 is provided around the outer periphery of the insulator 21 . The outer conductor 25 is, for example, a straight pipe or corrugated pipe made of aluminum or copper. A plurality of slots 23 are provided in the outer conductor 25 at predetermined intervals. The slot 23 is formed, for example, in the shape of a long hole with a certain inclination angle with respect to the longitudinal direction of the leaky coaxial cable 5. This slot 23 provides a function unique to the leaky coaxial cable of transmitting and receiving electromagnetic energy between the inside and outside of the leaky coaxial cable 5.

FIG. 5 is a conceptual diagram showing the arrangement of the slots 23 in the leaky coaxial cable 5. As shown in FIG. The leaky coaxial cable 5 is used by connecting a plurality of leaky coaxial cables 5 to each other. Between the cable connection part 31 and the terminal connection part 32 of the leaky coaxial cables 5, the farther the distance from the power feeding point (power feeding part 34), the more the arrangement angle of the slot 23 of the leaky coaxial cable 5 is in the cable axis direction. It is arranged so that it is larger than the Alternatively, the slots 23 may be arranged at smaller intervals such that the farther the distance from the power feeding point (power feeding unit 34), the higher the density of the slots 23.

An outer sheath 27 is provided around the outer periphery of the outer conductor 25 . The outer sheath 27 is provided so as to cover the outer periphery of the outer conductor 25, and is molded integrally with the support wire 29 via the neck. That is, the support wire 29 is covered with the outer sheath 27, and is disposed facing the outer conductor 25 and separated from the outer conductor 25 by a predetermined distance. The support wire 29 is made of, for example, a steel wire. The support wire 29 is generally provided for the purpose of providing dimensional stability to the leaky coaxial cable 5 by preventing the leaky coaxial cable 5 from expanding or contracting due to environmental temperature changes or loosening due to its own weight. This is the part used when hanging the product on a wall, etc. In the illustrated example, the slot 23 is arranged on the substantially opposite side to the support line 29. Note that the slot 23 may be provided at a position directly opposite to the support line 29 of the external conductor 25, or may be arranged at a predetermined angle from the position opposite to the support line 29.

As shown in FIG. 1, a cable support member 11 is arranged at a predetermined position in the longitudinal direction inside the trough body 3a. FIG. 6A is a perspective view showing the cable support member 11. The cable support member 11 is made of resin and/or rubber, and is made of the same material as the trough 3, for example. The cable support member 11 has an outer shape corresponding to the internal shape of the trough body 3a, and a support portion 33 is formed on the upper surface approximately at the center in the width direction. The support portion 33 is a recessed portion having a substantially semicircular arc shape (substantially semicircular shape), and is provided so as to penetrate both sides of the cable support member 11 . In addition, a groove 33a is further formed approximately in the center of the support portion 33 to accommodate the support wire 29 of the leaky coaxial cable 5. Here, although not particularly shown, one or more water drainage grooves may be formed on the contact surface between the support portion forming surface of the cable support member 11 and the bottom surface (upper surface) of the trough on the opposite side. Although the shape of the water drainage groove is not particularly limited, it may be, for example, a semicircular groove.

FIG. 6B is a diagram showing a process of arranging the leaky coaxial cable 5 on the cable support member 11. The leaky coaxial cable 5 is placed on the support portion 33 of the cable support member 11 with the support wire 29 facing downward (arrow C in the figure). At this time, the support wire 29 fits into the groove 33a, and approximately half the circumference of the main body of the leaky coaxial cable 5 is supported by the support portion 33. That is, the support portion 33 of the cable support member 11 is formed in a shape that allows the leaky coaxial cable 5 to be accommodated therein.

As described above, in the leaky coaxial cable installation structure 1, inside the closed space formed by the trough 3 in which the trough body 3a is covered with the trough lid 3b, resin and/or Alternatively, a cable support member 11 made of rubber is arranged. Further, the leaky coaxial cable 5 is placed on the support portion 33 of the cable support member 11 with the support wire 29 facing downward and the support wire 29 being housed in the groove 33a.

Next, a method of installing a leaky coaxial cable will be explained. First, the trough body 3a is fixed to concrete ground. 7A to 7D are diagrams showing the process of fixing the trough body 3a to the concrete ground 35, FIG. 7A is a sectional view showing the state in which the trough body 3a is installed on the concrete ground 35, and FIG. 7B is a diagram showing the process of fixing the trough body 3a to the concrete ground 35. It is an enlarged view of part B of FIG.

On the back surface of the bottom 7 of the trough body 3a, a pair of ribs 37 having a predetermined length are provided along the longitudinal direction of the trough body 3a at approximately the center of the trough body 3a in the width direction. A groove 39b is formed between the ribs 37 facing each other. Further, on the surface of the bottom portion 7 of the trough body 3a, a groove 39a having a predetermined length is provided along the longitudinal direction of the trough body 3a at a portion corresponding to the groove 39b.

As shown in FIG. 7C, a trough fixing bolt insertion hole 41 can be formed at any position in the longitudinal direction of the grooves 39a, 39b. As shown in FIG. 7D, an anchor nut 45 is buried in the concrete ground 35 in advance, and the anchor bolt 43 is inserted into the trough fixing bolt insertion hole 41 formed between the mutually opposing ribs 37 to connect the anchor nut 45. Screw together. As described above, the trough main body 3a can be fixed to the concrete ground 35. Here, the trough may be fixed to the concrete ground by fixing anchor bolts to the ground and fixing the trough body 3a with nuts.

Note that the trough fixing bolt insertion hole 41 may be formed in the trough body 3a in advance. FIG. 8A is a plan view of the trough body 3a, and FIG. 8B is a bottom view of the trough body 3a. An elongated trough fixing bolt insertion hole 41 is formed approximately at the center of the trough body 3a in the longitudinal direction and the width direction. By aligning the position where the anchor nut 45 is buried in the concrete ground 35 with the position of the existing trough fixing bolt insertion hole 41, there is no need to newly form the trough fixing bolt insertion hole 41.

In this manner, in the step of fixing the trough 3 to the concrete ground 35, the trough body 3a can be fixed to the concrete ground 35 by inserting the anchor bolt 43 into the trough fixing bolt insertion hole 41. At this time, the trough fixing bolt insertion hole 41 is an elongated hole (for example, approximately rectangular or oval) formed approximately at the center of the trough body 3a in the longitudinal direction and the width direction. You may use an existing one. Alternatively, it may be formed at any position in a groove formed in the widthwise center of the back surface of the bottom portion 7 between mutually opposing ribs 37 having a predetermined length along the longitudinal direction of the trough 3. Here, the ellipse is a figure in which both ends of the short side of the ellipse face outward in an arc shape.

In this manner, the existing trough fixing bolt insertion hole 41 formed in the trough body 3a is an elongated hole extending with a predetermined dimension in the longitudinal direction of the trough. Moreover, the trough fixing bolt insertion hole 41 can also be formed at any position in the grooves 39a, 39b of the trough body 3a. Therefore, it is possible to adjust the formation position of the trough fixing bolt insertion hole 41 so as to correspond to the fixing position of the anchor bolt 43 (anchor nut 45 buried position).

In addition, although not particularly shown, when fixing the trough body 3a to concrete ground, connecting portions 13a and 13b are formed at one end and the other end of the trough body 3a, respectively. can be connected by tilting them to each other at a predetermined angle. It goes without saying that by doing this, it is possible to absorb misalignment in the formation position of the anchor nut provided in the concrete ground.
As described above, the fixing position of the anchor nut can be adjusted by adjusting the connection angle of the connecting parts 13a, 13b of the trough main body 3a in at least one of the left-right direction and the vertical direction. In addition to adjusting the distance between the formation positions of the trough body in the longitudinal direction, it is also possible to adjust both the displacement of the fixed position of the trough body in the width direction of the trough body.

Next, the cable support member 11 is placed inside the trough body 3a. FIG. 9A is a diagram showing a process of arranging the cable support member 11 inside the trough main body 3a, and FIG. 9B is a diagram showing a state in which the cable support member 11 is arranged at a predetermined position of the trough main body 3a.

As described above, the cable support member 11 is formed separately from the trough body 3a. The cable support member 11 is fixed to a fixing portion 49 formed inside the cross section of the trough body 3a. The fixing part 49 includes inner ribs 47a formed on the inner surface of the trough body 3a and facing each other so that the cable support member 11 can be inserted and fixed therein. The cable support member 11 is inserted and fixed between the inner ribs 47a (arrow D in FIG. 9A).

By doing so, the installation position of the cable support member 11 can be easily grasped, and the work is easy because the cable support member 11 can be fixed to the trough body 3a simply by inserting it between the inner ribs 47a . be. In addition, it is preferable that only the inner ribs 47a facing each other are formed on the inner surface of the trough main body 3a, and the inner ribs 47b are not formed on the inner bottom surface. In this way, when the inner ribs 47a are formed only on the inner surface of the trough body 3a and the cable support member 11 is inserted between the inner ribs 47a and fixed only by the inner ribs 47a, a water drainage hole is provided on the bottom surface. It is desirable to use a cable support member in which a groove is formed.

In this case, even if rainwater intrudes into the inside of the trough body 3a for some reason, the infiltrated rainwater will not be dammed up by the inner rib 47b of the trough body 3a. A water drainage groove formed on the bottom surface of the cable support member 11 forms a flow path on the inner bottom surface of the trough body 3a, and directs the water accumulated at the bottom of the trough body 3a toward the connection part of the trough body 3a. This is because it can be washed away. Thereby, even if rainwater accumulates on the inner bottom surface of the trough body 3a, the influence of rainwater on electromagnetic wave characteristics such as reflection and absorption of electromagnetic waves emitted from the leaky coaxial cable 5 can be reduced.

Next, the leaky coaxial cable 5 is placed on the support portion 33 of the cable support member 11 placed inside the trough body 3a, with the support wire 29 facing downward. Finally, the trough lid 3b is placed on the trough body 3a and fixed with bolts 17 (see FIG. 2), thereby forming the leaky coaxial cable laying structure 1.

Note that the cable support member 11 may be formed integrally with the trough body 3a instead of being separate from the trough body 3a. 10A is a partial plan view of the trough body 3a integrally formed with the cable support member 11, and FIG. 10B is a sectional view taken along the line FF in FIG. 10A.

In the embodiment shown in FIGS. 10A and 10B, the cable support member 11 is formed integrally with the trough body 3a made of resin. Therefore, the trough body 3a does not require a fixing part for fixing the cable support member 11. In this way, the cable support member 11 may be formed integrally with the resin-made trough body 3a, or may be formed separately. In addition, although the following description demonstrates the example where the cable support member 11 is formed separately from the trough main body 3a, it is the same when it is formed integrally.

FIG. 11 is a front view of the leaky coaxial cable installation structure 1. The cable support member 11 allows the leaky coaxial cable 5 to be placed at a predetermined height from the bottom 7 of the trough body 3a. Here, as described above, the slot 23 is formed in the leaky coaxial cable 5 on the side opposite to the support wire 29. Therefore, the slot 23 of the leaky coaxial cable 5 is arranged generally upward.

E in the figure is the range in which the center position of the slot 23 is arranged. In this manner, the cable support member 11 can support the leaky coaxial cable 5 such that the slot 23 of the leaky coaxial cable 5 is at a predetermined height and at a predetermined angle from the bottom 7 of the trough body 3a.

Note that the arrangement of the leaky coaxial cable 5 is not limited to the example shown in FIG. 11. For example, like the leaky coaxial cable installation structure 1b shown in FIG. 12, the support wire 29 of the leaky coaxial cable 5 does not have to be arranged so as to face directly below. In this case, the groove 33a of the cable support member 11 may be formed obliquely. By doing so, the range E of the center position of the slot 23 can be directed diagonally at a predetermined angle.

FIG. 13 is an example of a conceptual plan view of the leaky coaxial cable installation structure 1 (however, the illustration of the trough lid 3b is omitted). As described above, a plurality of cable support members 11 are arranged at predetermined intervals at predetermined positions on the trough structure 51 in which a plurality of troughs 3 are connected. The leaky coaxial cable 5 is placed on the support portion 33 formed at a predetermined height of the cable support member 11 inside the closed space formed by the trough structure 51 .

Here, as described above, the leaky coaxial cables 5 are connected to each other by the cable connection part 31. At this time, the cable connection part 31 is arranged in the trough structure 51 at a position other than the arrangement part of the cable support member 11. Therefore, the cable connection portion 31 and the cable support member 11 do not interfere with each other.

Further, the length of the trough body 3a and the trough lid 3b that constitute the trough structure is usually 1 m, and the cable support members 11 can be provided at predetermined intervals at predetermined positions in the longitudinal direction of the trough structure 51. For example, they can be set at intervals of 1 m or more and 6 m or less, and are preferably provided at intervals of 2 m or more and 6 m or less (G in the figure). By supporting the cables at intervals of 6 m or less, it is possible to prevent the cable support members 11 from loosening due to their own weight, and to stably and reliably support the leaky coaxial cable. Furthermore, by providing the cable support members 11 at intervals of 2 m or more, it is possible to prevent the cable support members 11 from loosening due to their own weight, and to reduce the number of cable support members 11 installed. It is desirable to support them at intervals.

Further, even if the length of the trough body 3a and the trough lid 3b is not 1 m, the above effect can be obtained by providing the cable support members 11 at intervals of 2 m or more and 6 m or less. Here, the cable support member 11 is formed at a predetermined position of the trough 3. Therefore, when using troughs 3 having a length of 1 m, three troughs 3 must be connected in order to set the interval between cable support members 11 to a predetermined length of 2 m. Further, in order to set the interval between the cable support members 11 to a predetermined length of 5 m, six troughs 3 must be connected. Moreover, when the length of the trough 3 is not 1 m, it is sufficient to combine the troughs as appropriate depending on the length of the trough 3.

Further, by providing the cable support members 11 at intervals of 6 m or less, it is possible to prevent the cable support members 11 from loosening due to their own weight. Therefore, changes in the direction in which electromagnetic waves are radiated from the slot 23 due to slack in the leaky coaxial cable 5 can be suppressed, and stable transmission and reception can be achieved. Furthermore, due to the slackness of the leaky coaxial cable 5, the leaky coaxial cable 5 does not come into contact with the bottom part 7 of the trough body 3a, which prevents the leaky coaxial cable 5 from getting wet or damaged when rainwater enters the trough 3. be able to. Here, when the cable support member 11 is integrally molded on the trough body 3a, the trough body 3a on which the cable support member 11 is integrally molded and the trough body 3a on which the cable support member 11 is not integrally molded are combined to form a trough structure. It is sufficient to form the body 51.

As explained above, according to the present embodiment, the leaky coaxial cable 5 is housed in the trough 3, so that the leaky coaxial cable 5 is not directly affected by rain or wind pressure from the train. , the communication characteristics of the leaky coaxial cable 5 can be stabilized. Therefore, the installation state of the leaky coaxial cable 5 can be stably maintained over a long period of time. Further, unlike a hanging type, there is no need for a support or a fixing jig for hanging the leaky coaxial cable 5. Furthermore, since the leaky coaxial cable 5 is installed within the trough 3, deterioration of the cable covering member due to changes in external environmental temperature or ultraviolet irradiation can be alleviated.

Further, by using an existing hole as the trough fixing bolt insertion hole 41 through which the anchor bolt 43 for fixing the trough body 3a to the concrete ground 35 is inserted, no additional drilling is required. Furthermore, even if the anchor nut 45 is slightly misaligned, alignment is easy if the trough fixing bolt insertion hole 41 is an elongated hole. Furthermore, even if the anchor nut 45 is disposed out of position in the existing hole, the trough fixing bolt insertion hole 41 can be easily formed at a position along the grooves 39a, 39b. At this time, the rib 37 can be used as a guide for forming the trough fixing bolt insertion hole 41.

Further, both the trough body 3a and the trough lid 3b are made of resin that hardly shields radio waves. Therefore, even if the leaky coaxial cable 5 is housed inside the closed space surrounded by the trough body 3a and the trough lid 3b, the leakage coaxial cable 5 inside the trough 3 and the antenna outside the trough 3 will Stable transmission and reception with little absorption of radio waves is possible.

Further, bolts 17 are used to fix the trough body 3a and the trough lid 3b, and anchor bolts 43 are used to fix the trough body 3a and the concrete ground 35. Therefore, angle members or band-shaped members are not used to fix the trough body 3a and the trough lid 3b or to fix the trough body 3a and the concrete ground 35, so the influence of electromagnetic waves due to the fixing members is suppressed. be able to.

Also, a leaky coaxial cable 5 is arranged on the cable support member 11. Therefore, the leaky coaxial cable 5 can be supported at a predetermined height inside the trough body 3a. Therefore, even if water enters the trough body 3a, it is possible to prevent the leaky coaxial cable 5 from getting wet. In addition, by arranging it a predetermined distance from the concrete ground 35, the influence of radio wave reflection on the concrete ground 35 can also be suppressed. Furthermore, since the top of the anchor bolt 43 and the bottom of the leaky coaxial cable 5 are arranged a predetermined distance apart, there is no interference between the two. Compared to the case where the leaky coaxial cable 5 is placed directly on the concrete ground 35, it is possible to reduce the influence of reflection from the concrete ground 35, and furthermore, due to the curl of the leaky coaxial cable 5, the leaky coaxial cable 5 Meandering can be prevented.

Further, in a cross section perpendicular to the longitudinal direction of the trough body 3a, the leaky coaxial cable 5 can be always arranged at a constant angle inside the trough body 3a by the cable support member 11. That is, it is possible to arrange the slot 23 of the leaky coaxial cable 5 so that it always faces in a constant direction. Therefore, signals can be transmitted and received favorably between an antenna provided on a train and the leaky coaxial cable 5, for example.

Here, in the leaky coaxial cable 5, the amount of leakage of radio waves can be controlled by the design of the slot 23. In this embodiment, as the distance from the power feeding point (power feeding unit 34) increases, the arrangement angle of the slots 23 of the leaky coaxial cable 5 increases with respect to the cable axis direction, or the slots 23 become denser. will be placed in Therefore, by utilizing this characteristic and designing so that the arrangement angle and arrangement density of the slots 23 become larger as the distance from the feeding point increases, the relay interval can be increased. For example, the relay interval of the leaky coaxial cable 5 can be set to 1300 m to 1500 m, but the relay interval is not necessarily limited to the above range and can also be set to 1000 m or less.

Note that, for example, an amplifier or the like may be installed at the cable connection portion 31 of the leaky coaxial cable 5. By doing so, even when a plurality of leaky coaxial cables 5 are connected, stable signal transmission and reception can be performed over the entire length.

[Second embodiment]
Next, a second embodiment will be described. FIG. 14A is a perspective view of the cable support member 11a used in the second embodiment, and FIG. 14B is a front view. Note that in the following description, components that perform the same functions as those in the first embodiment are given the same reference numerals as in FIGS. 1 to 13, and redundant description will be omitted.

The cable support member 11a has substantially the same configuration as the cable support member 11, but the arrangement of the support portion 33 is different. In the cable support member 11 described above, the center line of the support portion 33 is arranged approximately at the center of the cable support member 11 in the width direction (on the line H in FIG. 14B). On the other hand, the cable support member 11a is arranged at a position where the center line of the support portion 33 (line I in FIG. 14B) is shifted from the center in the width direction of the cable support member 11a.

FIG. 15 is an example of a conceptual plan view showing a leaky coaxial cable laying structure 1c in which the cable support member 11a is used (however, the illustration of the trough lid 3b is omitted). As described above, in the trough structure 51 in which the plurality of troughs 3 are connected, the plurality of cable support members 11a are arranged at predetermined intervals in the longitudinal direction. The leaky coaxial cable 5 is arranged in the support part 33 of each cable support member 11a.

Here, the cable support members 11a that are adjacent to each other in the longitudinal direction are formed in opposite directions. That is, the support portions 33 of the cable support member 11a are arranged such that the direction of displacement of the support portions 33 of the cable support member 11a changes alternately with respect to the width direction of the trough body 3a. In the illustrated example, the cable support members 11a are arranged with their orientations changed so that the support portion 33 is shifted from the right direction to the left direction to the right direction in the figure in order from the top in the figure.

The leaky coaxial cable 5 is disposed on the support portion 33 of the cable support member 11a. Further, the support portions 33 of the cable support member 11a are arranged in the width direction alternately with respect to the longitudinal direction of the trough structure 51. For this reason, the leaky coaxial cable 5 is bent and loosely arranged in a substantially S-shape so that continuous bent portions are formed alternately in the longitudinal direction of the trough structure 51. At this time, the leaky coaxial cable 5 is restrained by the cable support member 11a and is bent toward the center of the trough 3 at each end in the width (thickness) direction of the cable support member 11a. That is, the leaky coaxial cable 5 is bent in a predetermined direction at both ends of the cable support member 11a while being restrained by a distance corresponding to the width (thickness) of the cable support member 11a. Therefore, the stress generated in the leaky coaxial cable 5 is distributed to both sides of the cable support member 11a, and the stress is not concentrated at one point on the leaky coaxial cable 5 disposed in the center of the cable support member 11a.

The amount of deviation of the support part 33 from the center of the cable support member 11a can be evaluated, for example, by the amount by which the center of the approximately semicircular support part 33 deviates from the center of the cable support member 11a, and this is referred to as the offset amount. Define.

Note that the amount of offset of the support portion 33 of the cable support member 11a can be set according to the permissible bending angle of the leaky coaxial cable 5 used and the installation interval of the cable support member 11a. For example, if the outer conductor 25 of the leaky coaxial cable 5 is an aluminum tube, the bending angle can be set to 4 degrees, but considering safety since it will be repeatedly bent into an S-shape, the bending angle should be set to 2 degrees. It is desirable to keep it below °. Note that when the outer conductor 25 is formed of a copper tube, the S-shaped bending angle can be made larger than when the outer conductor is formed of an aluminum tube. However, in the present invention, the upper limit of the bending angle is set according to the bending angle of the aluminum tube. is 2°.

Here, the cable support members 11a formed with the support portions 33 offset may be used, and the directions of adjacent cable support members 11a separated by a predetermined distance may be reversed and arranged in a staggered manner. By doing so, the support portions 33 can be offset in opposite directions with respect to the center line of the cable support member 11a. Therefore, the total offset amount of the support portions 33 of adjacent cable support members 11a is twice the offset amount of the support portions 33 of each cable support member 11a.

For example, when the bending angle of the leaky coaxial cable 5 is 2 degrees, the amount of deviation of the leaky coaxial cable 5 is approximately 3.5 cm per 1 m, and approximately 7 cm per 2 m. Therefore, for example, when the cable support members 11a are arranged at 2 m intervals, the support portions 33 of the cable support members 11a may be formed offset by 3.5 cm from the center. In this way, for example, by arranging the cable support member 11a with an offset of 3.5 cm to the right, and arranging the next cable support member 11a in the opposite direction, the support part 33 can be offset by 3.5 cm to the left. can be placed.

Note that when the bending angle of the leaky coaxial cable 5 is 0.5°, the amount of deviation of the leaky coaxial cable 5 is approximately 0.87 cm per 1 m, and approximately 1.74 cm per 2 m. Here, if the bending angle is less than 0.5°, the amount of deviation of the bent portion of the leaky coaxial cable is too small, and the effect of providing extra length is insufficient. Therefore, the bending angle of the leaky coaxial cable 5 needs to be set to 0.5° or more and 2° or less, and preferably set to 1° or more and 2° or less.

By arranging the support portion 33 and the groove 33a of the cable support member 11a in different directions with different offset amounts in the longitudinal direction, the leaky coaxial cable 5 is guided along the support portion 33 and the groove 33a in the S-shape in plan view. It is arranged in a meandering manner. For example, when the outer diameter of the leaky coaxial cable is approximately 51 mm, the length of the groove 33a of the support part 33 of the support member in the longitudinal direction of the trough is 60 mm, but the length of the groove 33a may be determined as appropriate. .
Here, the S-shaped peaks and valleys are restrained in a short straight line by the grooves 33a of the support member 33, and the peaks and valleys are bent inward at both ends, resulting in an inflection near the center of the S-shape. A loose arrangement with points can be realized. By adopting this configuration, a margin is given to the length of the leaky coaxial cable 5 arranged in an S-shape, so that it can be stabilized even when tensile force is applied to the leaky coaxial cable 5 due to shaking such as an earthquake. The installed state is maintained.

The period of the above-mentioned slack arrangement is from 2 m to 6 m, which is the arrangement interval of the cable support members 11a. If the distance between the cable support members 11a exceeds 6 m, the influence of slack due to their own weight will appear, the height of the leaky coaxial cable 5 will become uneven, and communication characteristics will become unstable, which is not preferable. In addition, when the distance between the cable support members 11a is less than 2 m, it is difficult to stably bend the leaky coaxial cable at a small bending angle, and to prevent local stress concentration at the peaks and valleys of the S-shaped bend of the cable. becomes difficult to avoid. Moreover, at the same time, an increase in the number of installed cable support members 11a causes an unnecessary increase in cost. Therefore, the arrangement interval of the cable support members 11a is preferably 2 m to 6 m. By setting the arrangement interval to 6 m or less in this manner, the leaky coaxial cable itself is rigid and will not be affected by bending due to its own weight.

In addition, in the leaky coaxial cable installation structure 1c, the cable support member 11 may be used not only for the cable support member 11a but also for a part. That is, in the leaky coaxial cable installation structure 1c, the cable support member 11a is used at least in part, and the support portion 33 of the cable support member 11a is formed at a position offset by a predetermined distance from the center of the cable support member 11a in the width direction. All you have to do is stay there. By doing so, the leaky coaxial cable 5 can be loosely arranged in a substantially S-shape with respect to the longitudinal direction of the trough structure 51 on the cable support member 11a.

According to the second embodiment, effects similar to those of the first embodiment can be obtained. Further, by arranging the leaky coaxial cable 5 loosely in a substantially S-shape with respect to the longitudinal direction of the trough structure 51, it becomes possible to arrange the leaky coaxial cable 5 in a loose state. Therefore, when the leaky coaxial cable 5 receives external tension not only due to environmental temperature changes but also during earthquakes, stress can be alleviated, and deformation of the leaky coaxial cable can be prevented.

[Third embodiment]
Next, a third embodiment will be described. FIG. 16A is a perspective view of the cable support member 11b used in the third embodiment. The cable support member 11b has substantially the same configuration as the cable support member 11, but differs in that grooves 53 are formed on the side and bottom surfaces along the circumferential direction of the cable support member 11b.

FIG. 16B is a front view showing a state in which the leaky coaxial cable 5 is arranged on the cable support member 11b. As described above, the leaky coaxial cable 5 is arranged on the support portion 33 of the cable support member 11b. Further, a string-like fixing member 55 is arranged in the groove 53. As the string-like fixing member 55, for example, a binding band made of resin is used.

The leaky coaxial cable 5 can be fixed to the cable support member 11b by the string-like fixing member 55. That is, at least a portion of the leaky coaxial cable 5 placed on the cable support member 11b is tied to the cable support member 11b by the string-like fixing member 55 and fixed to the cable support member 11b. Here, as for the tightening force of the string-like fixing member, it is usually desirable to tighten it within a range that does not cause cross-sectional deformation of the leaky coaxial cable. Furthermore, when the leaky coaxial cable, which will be described later, is not pressed by a pressing body, the tightening force of the string-like fixing member may be applied within a range where the cross-sectional deformation strain rate of the leaky coaxial cable is 0.2%. In addition, in the leaky coaxial cable installation structure, the cable support members 11b may not be arranged at all positions, but the cable support members 11b may be arranged at least in some parts, and the cable support members 11 may be arranged in the rest. Further, in the cable support member 11b as well, the position of the support portion 33 may be offset in the width direction similarly to the cable support member 11a.

According to the third embodiment, the same effects as the first embodiment can be obtained. Furthermore, by fixing the leaky coaxial cable 5 to the cable support member 11b with the string-like fixing member 55, the leaky coaxial cable 5 will not be displaced from the support portion 33 of the cable support member 11b in the event of an earthquake or the like. Further, by increasing the tightening force of the string-like fixing member 55 that fixes the leaky coaxial cable 5, the leaky coaxial cable 5 can be stably fixed.

[Fourth embodiment]
Next, a fourth embodiment will be described. FIG. 17A is a front view of the leaky coaxial cable laying structure 1d before closing the trough lid 3b, and FIG. 17B is a front view of the leaky coaxial cable laying structure 1d with the trough lid 3b closed. . In the leaky coaxial cable installation structure 1d, a pressing body 59a is arranged on the back surface of the trough lid 3b. The pressing body 59a is a resin foam, for example, made of a polyethylene foam sheet, and is constructed by laminating a plurality of polyethylene foam sheets.

The pressing body 59a is disposed on the back surface of the trough lid 3b at a position corresponding to the position where the cable support member 11 is disposed when the trough lid 3b is closed. Therefore, when fixing the trough lid 3b to the trough body 3a with the bolts 17, the pressing body 59a is arranged above the leaky coaxial cable 5 on the cable support member 11.

In addition, in the leaky coaxial cable installation structure 1d, the pressing bodies 59a do not need to be arranged at all the parts where the cable support members 11 are arranged. That is, the pressing body 59a may be disposed above at least some of the cable support members 11.

Further, the thickness of the pressing body 59a is thicker than the gap between the back surface of the trough lid 3b and the upper end of the leaky coaxial cable 5 when the trough lid 3b is closed. Therefore, when fixing the trough lid 3b to the trough body 3a with the bolts 17, the pressing body 59a can be pressed by the trough lid 3b. Therefore, the leaky coaxial cable 5 placed on the cable support member 11 is pressed by the pressing body 59a (arrow J in FIG. 17B), and the leaky coaxial cable 5 can be fixed.

Note that the pressing body 59a made of polyethylene foam sheet has an extremely large amount of deformation. Therefore, as shown in FIG. 17A, even if the pressing body 59a is approximately rectangular in front view, when pressing the leaky coaxial cable 5, the pressing body 59a deforms along the outer shape of the leaky coaxial cable 5. and tightly adheres to the upper surface of the leaky coaxial cable 5. Therefore, the leaky coaxial cable 5 is sandwiched between the cable support member 11 and the pressing body 59b, and the leaky coaxial cable 5 can be efficiently fixed.

For example, a polyethylene foam sheet (a 40 times foamed product: a laminate of six 10 mm thick sheets) is used as the pressing body 59a, and the polyethylene foam resin sheet has a predetermined thickness of dimensions: 60 mm thick x 120 mm long x 140 mm wide. When the top of the leaky coaxial cable, which has the largest pressing amount, is pressed by 16%, the increase in the pulling force of the leaky coaxial cable 5 due to the increase in the pressing force by the pressing body 59a is 8.0 kg. Similarly, when a polyethylene foam sheet (40 times foamed product) is used as the pressing body 59a and pressed by 30%, the increase in the pulling force of the leaky coaxial cable 5 due to the increase in the pressing force by the pressing body 59a is 13 .0 kg. Therefore, when 50 pressing bodies 59a are arranged in a 100 m section at 2 m intervals, the increase in the pulling force of the leaky coaxial cable 5 is 400 kg and 650 kg, respectively. Here, for example, when the leaky coaxial cable is pressed by 30%, the cross-sectional deformation strain rate corresponding to the change in diameter from 51.01 mm to 50.93 mm before and after pressing is 0.16%, which should be 0.20% or less. becomes possible. That is, by providing polyethylene foam sheets with a foaming ratio of 40 times at predetermined intervals of 2 m, it is possible to increase the pulling force of the leaky coaxial cable per 100 m to 400 kg or more. Thereby, by adjusting the pressing distance and the amount of pressing, it is possible to secure a pulling force of 300 kg or more per 100 m.

Note that the pressing body is not limited to one made of polyethylene foam sheet. FIG. 18A is a front view of the leaky coaxial cable laying structure 1e before closing the trough lid 3b, and FIG. 18B is a front view of the leaky coaxial cable laying structure 1e with the trough lid 3b closed. . In the leaky coaxial cable installation structure 1e, a pressing body 59b is arranged on the back surface of the trough lid 3b. The pressing body 59b is a rubber molded body.

The pressing body 59b made of a rubber molded body has a smaller amount of deformation than the pressing body 59a made of a polyethylene foam sheet. For this reason, a notch 61 having a shape corresponding to the outer shape of the leaky coaxial cable 5 is formed in advance in the pressing body 59b. For example, as illustrated, a semicircular notch 61 is formed on the lower surface of the pressing body 59b.

The thickness of the pressing body 59b in the notch 61 is approximately equal to or slightly thicker than the gap between the back surface of the trough lid 3b and the upper end of the leaky coaxial cable 5 when the trough lid 3b is closed. Therefore, when the pressing body 59b is pressed by the trough lid 3b when fixing the trough lid 3b to the trough body 3a with the bolts 17, the leakage coaxial cable 5 placed on the cable support member 11 is caused by the pressing body 59b. It is pressed (arrow K in FIG. 18B). Therefore, the leaky coaxial cable 5 can be fixed. In this case, the leaky coaxial cable 5 is sandwiched and fixed between the support portion 33 of the cable support member 11 and the notch 61 of the pressing body 59b.

According to the fourth embodiment, effects similar to those of the first embodiment can be obtained. Furthermore, since the leaky coaxial cable 5 is pressed by the pressing bodies 59a and 59b, a frictional force can be applied to the leaky coaxial cable 5 through contact between the leaky coaxial cable 5 and the pressing bodies 59a and 59b. Therefore, it is possible to increase the resistance force against the leaky coaxial cable 5 against expansion and contraction in the axial direction, and to increase the resistance to pulling it out. As a result, it becomes difficult to pull out the leaky coaxial cable 5 in one direction from inside the trough body 3a. Therefore, it is possible to prevent the leaky coaxial cable 5 from being stolen. Here, when comparing both the press body 59a made of a laminate of polyethylene foam resin sheets and the press body 59b made of a rubber molded body, the former press body 59a is made of a polyethylene foam material, which is a low dielectric constant material. Furthermore, since it is made of a material with a low dielectric constant, compared to the latter rubber pressing body 59b, it can be used as a good pressing body that does not disturb the electromagnetic field radiated from the leaky coaxial cable due to its low dielectric constant property.

[Communication characteristics confirmation test of concrete trough and resin trough]
As mentioned above, the leaky coaxial cable is a cable that transmits and receives radio waves and performs wireless communication with trains. For this reason, if a cable is placed in a trough for the purpose of cable protection, the trough may cause radio wave propagation loss, which may deteriorate transmission and reception characteristics with the train. In other words, by storing it in the trough, the coupling loss characteristics may deteriorate. Furthermore, since a leaky coaxial cable is an open transmission path, if there is a trough around it, the radio waves transmitted inside the leaky coaxial cable may also be affected. In other words, transmission loss characteristics may deteriorate. For this reason, a test was conducted to confirm the communication characteristics (coupling loss characteristics and transmission loss characteristics) of the resin trough structure. At this time, we also compared the case where the cable was simply placed on a cable support member on the concrete ground without using a resin trough structure.

(Communication characteristics confirmation test method)
The leaky coaxial cable was laid for a predetermined length with tension applied to the support wire, and the transmission loss and coupling loss, which are the attenuation of the leaky coaxial cable, were measured. In the measurement, test material A was a reference material in which a leaky coaxial cable was placed directly at a predetermined height on a cable support member placed directly on the concrete ground surface. On the other hand, test material B was constructed in which a trough lid was placed over the trough body to form a closed space, and a leaky coaxial cable was placed on the support part at a predetermined height of the cable support member in the closed space within the trough. , test material C, and the communication characteristics of each test material were compared. The cable support members were arranged at 2 m intervals, and the leaky coaxial cable was placed in a straight line with a length of about 10 m on the support portions at a predetermined height so that the slots faced in a predetermined direction. Here, the state in which the leaky coaxial cable was placed on the trough structure during the test will be explained in detail. The internal dimensions of the trough body in the trough structure used in the test were 170 mm in width x 145 mm in height x approximately 1000 mm in length, and a support member was placed inside the trough body. The support member has dimensions of 150 mm width x 80 mm height x 60 mm length (trough longitudinal direction), and has a semicircular (27R) support part at the center in the width direction. A groove for accommodating the support wire is formed at the lowermost end of the support portion. A leaky coaxial cable is placed on the support portion, and a trough lid is placed over the side wall portion of the trough body. At this time, a space of about 40 mm in height can be secured between the upper part of the leaky coaxial cable and the trough cover.

Here, the heights at which the cable support members of test material A, test material B, and test material C are arranged are made using resin sheets so that they are all constant according to the bottom thickness of the trough body of test material C. Adjusted to 50mm. Here, a polyolefin-based recycled resin trough described later was used for test material B, and a concrete trough was used for test material C, but the resin trough used for test material B and the concrete trough used for test material C were used. The troughs used were of the same size standard. Note that the polyolefin-based recycled resin used for Test Material B contained a total of 36% by mass of inorganic substances based on the total mass of the recycled resin. In addition, the mass ratio of each inorganic substance to the entire inorganic resin material of test material B was 19% by mass of magnesium hydroxide, 15% by mass of calcium carbonate, and 2% by mass of titanium oxide, taking into consideration strength, flame retardance, weather resistance, etc. %.

Furthermore, in all test materials, the same cable support member was used in which the groove into which the support wire was inserted was formed perpendicularly to the bottom surface of the cable support member. That is, the slot of the leaky coaxial cable was placed at a height of about 40 mm from the bottom of the cable support member so that it faced vertically upward with respect to the concrete ground. Therefore, the supporting height of the leaky coaxial cable from the concrete ground is the same for all test materials.

Here, for test material B, a trough body and a trough lid made of polyolefin-based recycled resin were used, and for test material C, a trough body and a trough lid made of concrete were used. Communication characteristics of these test material A, test material B, and test material C were evaluated. In addition, evaluation was also made when the surfaces of the trough body and trough lid of Test Material B and Test Material C were respectively wetted with water. In this case, in order to make the trough body and trough lid absorb water, the trough body and trough lid were immersed in water in a tray for 24 hours, and then the trough was taken out from the tray and tilted several times to remove water adhering to the surface. Test materials corresponding to these test materials B and C were designated as test materials D and test materials E, and the communication characteristics of test materials D and E were also evaluated. At this time, the support height of the leaky coaxial cable in the case of test material D and test material E was set in the same manner as in the case of test material B and test material C.

Specifically, the coupling loss characteristics are measured by the following method. A CW (continuous wave) signal at a predetermined frequency is inputted from one end (one end) of the leaky coaxial cable using a transmitter or the like, and the CW signal is transmitted inside the leaky coaxial cable. At this time, a non-reflection terminating resistor is connected to the other end (opposite one end). Then, the strength of the CW signal of the radio waves radiated from the leaky coaxial cable is received using a receiver such as a spectrum analyzer using a half-wavelength dipole antenna installed at a height of 1.5 m directly above the leaky coaxial cable. . At this time, the measurement was performed by moving a half-wavelength dipole antenna at a predetermined speed along the 10 m length of the leaky coaxial cable. The decibel difference between the strength of the CW signal transmitted inside this leaky coaxial cable and the strength of the CW signal received by the half-wavelength dipole antenna immediately above it was taken as the coupling loss, which was averaged in the longitudinal direction of the cable.

On the other hand, the transmission loss characteristics are specifically measured by the following method. A CW signal in a predetermined frequency range is input from one end (one end) of the leaky coaxial cable using a network analyzer or a spectrum analyzer with a tracking generator. Then, the CW signal output from the other end (opposite end) is received using the same measuring device. The decibel difference between the strengths of these two signals was defined as the transmission loss.

Table 1 shows the communication characteristic evaluation test results of leaky coaxial cables made of various test materials. At this time, the transmission loss was taken as the average value with respect to the frequency of the measurement results from 400 to 440 MHz. Further, assuming that the actual length of one section of the leaky coaxial cable is approximately 1.5 km, the unit of display is a value converted to dB/km.

(Communication characteristics evaluation results)
The transmission loss of test material B using a resin trough and reference test material A in the 400 MHz to 440 MHz band was approximately the same, about 22 dB/km. On the other hand, the test material C using a concrete trough was 27 dB/km, and the test material C using a concrete trough was inferior to the test material B using a resin trough. Furthermore, the coupling loss of the reference test material A in the 400MHz and 440MHz bands is both 63dB, while the coupling loss of the test material B is 62dB at 400MHz and 63dB at 440MHz, and the two are almost equivalent. Ta. On the other hand, the coupling loss of test material C using a concrete trough increased by 3 dB at 400 MHz and by 5 dB at 440 MHz compared to the reference test material A. Here, in the case of the concrete trough, not only the coupling loss (average value) was large, but also the variation was large.

In this way, the communication characteristics when using a resin trough structure are such that the transmission loss is within ±1 dB/km and the coupling loss is within ±1 dB compared to the case where a resin trough is not used (reference). Met. In other words, even if a resin trough structure is used, the transmission loss and coupling loss will be at least within ±2 dB/km, or within ±2 dB, compared to the case without a resin trough (reference). It was confirmed that the characteristics were satisfied.

Furthermore, the outer and inner surfaces of a resin trough were wetted with water and absorbed as test material D, and the outer and inner surfaces of a concrete trough were wetted with water and allowed to absorb water as test material E. A confirmation test was conducted. As a result, for test material D using a resin trough, even if the outer and inner surfaces of the trough were wetted with water and allowed to absorb water, the outer and inner surfaces of the trough hardly absorbed any water, so both transmission loss and coupling loss were low. It is almost the same as when the surface and inner surfaces are dry. On the other hand, in the case of test material E, in which the outer and inner surfaces of the concrete trough were wetted with water and absorbed, the transmission loss increased by 3 dB/km and the coupling loss increased by approximately 1 dB due to water absorption by the concrete. Both loss and coupling loss tended to increase.

Based on the above, a resin cable support member is placed inside the closed space formed by the trough structure using a resin trough body and a trough lid, and a leaky coaxial cable is placed on it at a predetermined height and angle. The communication characteristics under the specified conditions in the 400 to 440 MHz band when placed in It was confirmed that the communication characteristics were such that the change in transmission loss was within ±1 dB/km, and the change in coupling loss was within ±1 dB, compared to the case where the device was placed at a predetermined height and at a predetermined angle. That is, it is possible to obtain communication characteristics in which at least transmission loss and coupling loss are within ±2 dB/km and within ±2 dB, respectively.
Considering the effects of rainwater, if there is a lot of water or rainwater near a leaky coaxial cable, the transmission loss characteristics and coupling loss characteristics of the leaky coaxial cable will deteriorate significantly because water itself has strong electromagnetic wave absorption characteristics. However, if the leaky coaxial cable is housed in a trough with a support member and a certain distance can be secured from the top surface of the leaky coaxial cable to the trough structure, for example, about 40 mm, it is close to the condition of flooding. Since the presence of water near the leaky coaxial cable can be avoided even under such conditions, deterioration of transmission loss characteristics and coupling loss characteristics can be suppressed.

Similarly, as a result of a communication characteristic confirmation test in the 400 to 440 MHz band of the trough structure, even when the outer and inner surfaces of the trough structure were wetted with water and absorbed water, the outer and inner surfaces of the trough structure were Communication characteristics equivalent to those obtained when the surface was dry were obtained. Furthermore, when compared with the reference, it was confirmed that the transmission loss change was within ±1 dB/km, and the coupling loss change was within ±1 dB. It is possible to obtain communication characteristics in which changes are within ±2 dB/km and within ±2 dB, respectively. On the other hand, it can be seen that the communication characteristics of the concrete trough when wetted with water and absorbed by the resin trough are even worse than when it is dry.

(Water absorption rate of test material)
The test material B is a polyolefin recycled resin containing inorganic substances in a total of 36% by mass of the total mass of the recycled resin, and the water absorption rate after water absorption at 23°C for 24 hours was measured based on JIS K7209, which is equivalent to ASTM D570. The ratio was 0.13%, which satisfied 0.15% or less. Note that the water absorption rate of the polyolefin resin that does not contain recycled materials or inorganic materials is 0.025%, which satisfies 0.03% or less. In addition, the water absorption rate of concrete based on JIS A 1110 varies depending on the type of aggregate used for concrete and the ratio of water to cement at the time of pouring, but the water absorption rate after a 24-hour water absorption test is at least 2. % or more. Therefore, it is known that the water absorption rate of concrete is one order of magnitude higher than that of recycled polyolefin resins. This is considered to be the reason why the transmission loss and coupling loss of the concrete trough decrease due to water absorption, even though the transmission loss and coupling loss do not increase even when a recycled resin trough containing a predetermined amount of inorganic substances is used.

(Corrosion resistance confirmation test of test material)
Further, in a test in which the recycled polyolefin resin consisting of the test material B was immersed at room temperature for 24 hours in accordance with JIS K7114, the following corrosion resistance confirmation test was conducted to determine the respective mass change rates.
(1) Immersion test with 3% NaCl aqueous solution, which is a seawater simulating solution.
(2) 30% CaCl ₂ immersion test as a snow melting agent simulating liquid.
(3) An immersion test using a test liquid prepared by diluting a liquid mixture of H ₂ SO ₄ and HNO ₃ at a ratio of 2:1 to a concentration of 1% as an acid rain simulating liquid.
In addition, for each test, three test pieces were prepared and tested, and the average value of the three pieces was determined. The results of the test are shown in Table 2.

As a result, it was confirmed that in any of the above tests, the mass change rate of the mass of the test piece after the test with respect to the mass of the test piece before the test was 0.1% or less. In this way, the recycled resin trough for communication using leaky coaxial cables of the present application satisfied all of the environmental tests of seawater simulating liquid, snow melting agent simulating liquid, and acid rain simulating liquid, so it can withstand harsh external environments. can be followed.

Furthermore, regarding the recycled polyolefin resin made of test material B, a test was conducted to confirm weather resistance in addition to corrosion resistance. For this test, a weather resistance acceleration tester (ISuper UV tester: model number SUV-W161) manufactured by Iwasaki Electric Co., Ltd. was used. For polyolefin-based recycled resin, each predetermined level is set at eight levels: from 250 hours, at 250 hour intervals, up to 2000 hours, 250 hours, 500 hours, 750 hours, 1000 hours, 1250 hours, 1500 hours, 1750 hours, and 2000 hours. The specimens were irradiated with ultraviolet light for a certain period of time under predetermined conditions, and the tensile strength and Charpy impact value of each specimen was determined.

Here, a metal halide lamp for a weather resistance tester manufactured by Iwasaki Electric Co., Ltd. that irradiates ultraviolet rays with a wavelength of 295 nm or more was used as the light source of the weather resistance acceleration tester. The conditions for ultraviolet light irradiation were such that the intensity of the ultraviolet light irradiation was 90 mW/cm ² , and the ultraviolet light irradiation was performed in an environment with a humidity of 50% without spraying assuming rain. In addition, each test piece and test were conducted in accordance with JIS K7161 and JIS K7162. Here, the surface of the tensile test piece was used as the irradiation surface, and the Charpy impact test piece was irradiated with ultraviolet light from a direction perpendicular to the notch-formed surface, that is, from the normal direction of the notch-formed surface. The test results are shown in Table 3.

As shown in Table 3, with respect to the tensile strength and Charpy impact value of the test piece before irradiation with ultraviolet light, the residual rate of tensile strength and Charpy impact value of the test piece after 2000 hours of ultraviolet light irradiation was 95% or more, and the remaining Charpy impact value of the test piece after 2000 hours of ultraviolet light irradiation was The ratio was 90% or more, and it was confirmed that the material had sufficient strength and impact properties without any sudden decrease in strength.

Although not listed in Table 1, in addition to the recycled polyolefin resin material used in the communication characteristic evaluation described above, similar tests were conducted using a trough made of high-density polyethylene resin made of virgin polyolefin resin. A communication characteristic evaluation test was conducted. Even when using a high-density polyethylene resin trough body and trough lid, the transmission loss is within ±1 dB/km and the coupling loss is within ±1 dB with respect to the reference material, similar to test material B and test material D. It was confirmed that it has communication characteristics within a range. That is, it has been found that it is possible to obtain communication characteristics in which transmission loss and coupling loss are within ±2 dB/km and within ±2 dB, respectively.

In order to reduce costs, the polyolefin resin forming the trough is preferably a recycled polyolefin resin having a predetermined strength, high corrosion resistance, and high weather resistance. At this time, inorganic substances such as calcium carbonate, magnesium hydroxide, or titanium oxide may be added in an amount of up to 40% by mass of the total mass of the recycled resin within a range that does not affect the communication characteristics, but usually the amount of inorganic substances is The content is desirably 34% by mass or more and 36% by mass or less. By incorporating approximately 36% by mass of inorganic substances into the recycled resin, a flame-retardant polyolefin resin with excellent weather resistance can be obtained. Therefore, even if an inorganic substance is added in a range of 36% by mass to 40% by mass based on the total mass of the polyolefin recycled resin, strength and telecommunication properties that pose no problem in practical use can be maintained. Further, it was confirmed that the polyolefin-based recycled resin has excellent telecommunication properties and no problems in corrosion resistance. Of course, if a polyolefin-based recycled resin is used, it will not only have almost the same strength as a polyolefin resin, but it will also be possible to reduce costs. For the resin trough, a general-purpose resin with a specified strength can be used instead of recycled resin, but in this case, virgin polyolefin resin, which has excellent dielectric properties and water resistance, is suitable instead of recycled polyolefin resin. ing.

The polyolefin recycled resin material containing inorganic substances preferably contains at least magnesium hydroxide and titanium oxide as inorganic substances and has a dielectric constant of 3.15 or less. In this case, it is desirable that the content of magnesium hydroxide is 18% by mass or more based on the total mass of the recycled polyolefin resin material. More preferably, the inorganic substances are magnesium hydroxide, calcium carbonate, and titanium oxide, and the content ratio of each of them to the total mass of the polyolefin-based recycled resin material is 18 to 21.3% by mass of magnesium hydroxide and 14% by mass of calcium carbonate. -16.5% by mass, titanium oxide 2-2.2% by mass, and the total content of inorganic substances is 34% by mass or more and 40% by mass or less based on the total mass of the polyolefin-based recycled resin material. This is desirable. By doing so, a recycled polyolefin resin material having excellent flame retardancy and communication properties can be obtained.

For example, such recycled polyolefin resin materials are effective as materials for structures or members for telecommunications. For example, by using the above-described trough structure, a communication method and communication system with excellent communication characteristics can be obtained.

(Dielectric constant measurement test of material forming the trough body)
<Measurement method of dielectric constant>
The optimum measurement method for dielectric constant measurement differs depending on the measurement frequency band, but in the 400 MHz frequency band as in the present invention, measurement by capacitance method is considered to be suitable. In addition, the dielectric constant of a material in which multiple inorganic substances are dispersed in a resin, such as the one of the present invention, becomes larger than that of only the base resin due to the inclusion of inorganic substances in the resin, and is further influenced by the state of dispersion of the inorganic substances. Therefore, it cannot be predicted without actual measurement.

In the present invention, the dielectric constant of the recycled polyolefin resin forming the trough structure was measured. For dielectric constant measurement, a test piece of width 15 mm x length 15 mm x thickness 2 mm obtained by kneading the resin and the inorganic material and then processing the resin and the inorganic material using a roll was used. Using the capacitance method, a wide frequency band of 100 MHz to 600 MHz is scanned to measure the dielectric constant of the test piece in the 400 to 440 MHz frequency band. The ratio was obtained and used as the measured value.

For the measurement, an E4991B impedance analyzer manufactured by KEYSIGHT TECHNOLOGIES was used. Using E16453A manufactured by the same company as a fixture for measuring the test piece, measurements were repeated five times, and the average value was taken as the dielectric constant in each frequency band.

<Material forming the trough body used for dielectric constant measurement>
Three types of materials, Test Material B, Test Material B1, and Test Material B2 described below, were prepared as materials for forming the trough body, and dielectric constant measurements were performed. For dielectric constant measurements, in addition to test material B, composition B1, which takes into account variations in resin composition, and composition B2, which takes variations in inorganic substances into consideration, were prepared as prototypes, and the dielectric constants were determined.

Here, test material B has an inorganic content that is the target composition of a recycled resin. Moreover, test material B1 has an increased amount of polypropylene in the resin composition constituting the base resin. Specifically, test material B has a composition ratio of polyethylene:polypropylene = 9:1, while test material B1 has a composition ratio of polypropylene that is twice that of polypropylene and a composition ratio of polyethylene:polypropylene = 8:2. It is the material.

Test material B2 assumes a case where the content of inorganic substances is about 10% higher than the target standard composition of inorganic substances due to variations due to some reason. The inorganic content of magnesium hydroxide, calcium carbonate, and titanium oxide in test material B is 20.9% by mass, 16.5% by mass, and 2.2% by mass, respectively, for a total of 39.6% by mass. However, test material B2 is a material containing 21.3% by mass of magnesium hydroxide, 16.5% by mass of calcium carbonate, and 2.2% by mass of titanium oxide in order to properly set the total composition of inorganic substances to 40% by mass. .

In addition, the content of normally contained inorganic substances is added by blending calculations, so all inorganic substances do not increase by more than 10% at the same time, and in reality, the variation is within a few percent at most. considered to be a thing. Therefore, it is considered that suppressing the dielectric constant in test material B2 is sufficient to understand variations when the content of inorganic substances is large. In addition, in the present invention, conversely, as a case where the inorganic content is slightly lower than the target standard composition, the inorganic content of magnesium hydroxide, calcium carbonate, and titanium oxide is 18% by mass and 14% by mass, respectively. % by mass, 2% by mass, and a total of 34% by mass. Therefore, the test material corresponding to this composition was designated as test material B3, and in addition to test materials B1 and B2, the dielectric constant of test material B3 was measured. went.

<Results of dielectric constant measurement of the material forming the trough body>
Table 4 shows the dielectric constant measurement results of each test material as the dielectric constant measurement results of the materials forming the trough body. The measurement result of the dielectric constant of Test Material B was 3.04, which was constant at all frequencies in the frequency band of 400 to 440 MHz. Further, the dielectric constant of test material B1 whose resin composition contained a relatively large amount of polypropylene was 3.06 at frequencies of 400 and 420 MHz, and 3.07 at frequencies of 440 MHz. Furthermore, the dielectric constant of test material B2, which has approximately 10% more inorganic content, is 3.14 at frequencies of 400 and 420 MHz, and 3.15 at 440 MHz. The dielectric constant increased by about 0.10 to 0.11.

On the other hand, the dielectric constant of test material B3, which has a small content of inorganic substances, is 3.00 at frequencies of 400 MHz and 420 MHz, and 3.01 at frequencies of 440 MHz. The dielectric constant was slightly lower than that of test material B. From the above results, it is thought that the influence of inorganic materials on the dielectric constant of the materials contained in the resin is greater than the influence of fluctuations in resin components, but even in the case of B2, which has the highest inorganic content, Compared to Test Material B of the standard composition, the increase in dielectric constant was not so large and the influence was small. Incidentally, as mentioned above, the dielectric constant of polyethylene in this frequency band is 2.35, and that of polypropylene is 2.65.

<Comparison of permittivity with concrete trough>
Comparing the permittivity of test materials B to B3 in Table 4 with the permittivity of concrete, the permittivity of test material B is 3.04 over the measurement frequency band of 400MHz to 440MHz, and the inorganic content is Even the high dielectric constant of test material B2 is 3.15 at most. On the other hand, the dielectric constant of normal concrete is 6.0, which is much higher than that of the resin used in the above test material. Therefore, in the test results shown in Table 1, it seems that the communication characteristics of the concrete trough were inferior to the resin trough of the present invention.

<Telecommunications test results of test materials B1, B2, and B3>
Here, for confirmation, the telecommunication characteristics of test materials B1, B2, and B3 were evaluated at three frequencies of 400 MHz, 420 MHz, and 440 MHz under the same conditions as in Table 1. As a result, the transmission loss and coupling loss of test material B1 were 22 dB at all frequencies, 62 dB at 400 MHz and 420 MHz, and 63 dB at 440 MHz, which were the same as test material B.

On the other hand, test material B3, which has a small content of inorganic substances, had a transmission loss of 22 dB and a coupling loss that was constant at 62 MHz at any frequency from 400 to 440 MHz. Even in the case of test material B2, which has a high inorganic content, the transmission loss is 22 dB, but the coupling loss is 63 dB at all frequencies of 400 MHz, 420 MHz, and 440 MHz, indicating that the coupling loss increases by about 1 dB. .

It was found that the measurement results of the above test material B1, test material B2, and test material B3 showed the same results as the reference material in Table 1. In other words, when using the resin troughs of test material B1, test material B2, and test material B3, the transmission loss is lower than the reference case in which the leaky coaxial cable is exposed and placed without using a resin trough. It was confirmed that the coupling loss satisfies communication characteristics within a range of at least ±2 dB/km and within ±2 dB. Here, the reason why the leaky coaxial cable was placed on the support member inside the resin trough structure and the reference placed exposed showed the same telecommunication characteristics was due to the influence of reflected waves from the concrete ground. This is thought to be because it is larger.

Furthermore, when considering electromagnetic wave loss in resin troughs and concrete troughs, more precisely, it is necessary to consider the influence of the thickness of each material in addition to the dielectric constant. Therefore, we investigated the relationship between the thickness of the resin trough and the concrete trough used in the communication characteristic confirmation test of the present invention. In the case of a resin trough, the thickness of the trough lid is 10 mm, the wall thickness of the trough body is 7 mm, and the maximum wall thickness of the trough body is 10 mm, whereas in the case of a concrete trough, the thickness of the trough lid is 7 mm. The wall thickness in the trough body was 50 mm, and the maximum thickness of the trough body was 50 mm. Note that the reason why the wall thickness of a concrete trough is thicker than that of a resin trough is because the concrete trough absorbs electromagnetic waves, so it is not possible to place reinforcing bars, so the wall thickness needs to be thicker.

As mentioned above, all resin troughs not only have a lower dielectric constant than concrete troughs, but also have the maximum shielding of the outer periphery of the trough structure, which is the combination of the trough lid and trough body shielded by the trough. The thickness is less than or equal to 10 mm, which is less than the shielding thickness in the case of a concrete trough. Thus, the influence of the maximum shielding thickness of the trough structure as well as the dielectric constant is superimposed on the telecommunication properties. As a result, in the above-mentioned telecommunications test, the inorganic-containing polyolefin resin troughs of Test Material B, Test Material B1, Test Material B2, and Test Material B3 had better communication characteristics than the concrete troughs. became.

<Tensile test and bending test of the material forming the trough>
In the tensile test of the material forming the trough, test materials B, B1, B2, and B3 were processed into a sheet by injection molding, and then processed into a JIS No. 2 test piece in accordance with JIS-K7113 to determine the tensile speed. The speed was 50 mm/min. In the bending test, the bending elastic modulus was measured for test pieces of test materials B, B1, B2, and B3 at a sample thickness of 4 mm and a bending speed of 2 mm/min in accordance with JIS K7171. Specifically, a test piece (thickness: 4 mm, width: 10 mm, length: 80 mm) was made by injection molding, and a load was applied at a distance between fulcrums of 64 mm, a radius of curvature of the fulcrum and point of action of 5 mm, and a test speed of 2 mm/min. A bending test was conducted to measure the bending elastic modulus. Here, the tensile test and bending test were performed five times each, and the average values were determined as the tensile strength and bending elastic modulus.

Here, the bending elastic modulus Ef is
Bending stress σf ₁ measured at the amount of deflection at strain 0.0005 (εf ₁ )
Bending stress σf ₂ measured at the amount of deflection at strain 0.0025 (εf ₂ )
and divide these differences by the difference in their corresponding distortion amounts,
That is, the following formula Ef=(σf ₂ - σf ₁ )/(εf ₂ - εf ₁ )
It can be found by The results are shown in Table 5.

As a material for a trough structure for a leaky coaxial cable, any material having a tensile strength of 20 MPa or more and a bending modulus of 1000 MPa or more is considered usable. From the results of the tensile test and bending test shown in Table 5, all test materials B, B1, B2, and B3 satisfy these values.

Here, the material for the trough can be put to practical use as long as the trough structure satisfies predetermined electrical communication characteristics and has the necessary mechanical properties as a trough structure. Therefore, if a material with a dielectric constant of 3.15 or less, a tensile strength of 20 MPa or more, and a bending modulus of 1000 MPa or more is used as the material for the trough that accommodates the leaky coaxial cable, it is possible to prevent the leaky coaxial cable from leaking in telecommunications. It can be used as a material for a trough structure for leaky coaxial cables without impairing its properties. Therefore, any of the test materials B, B1, B2, and B3 can be used as a material for a trough body and a trough lid that constitute a trough structure for a leaky coaxial cable.

<Charpy impact test of the material forming the trough>
Cable storage structures may be hit by tools due to mistakes during track maintenance work, so materials for trough structures that accommodate leaky coaxial cables are required to have a certain impact strength. For example, it is expected to have mechanical properties of Charpy impact strength of 5 kJ/m ² or more. For this reason, Charpy impact tests were conducted on test materials B, B1, B2, and B3 at 23° C. using notched test pieces based on JIS K7111. The test was repeated five times and the average value was taken as the Charpy impact value. The Charpy impact test results shown in Table 5 all satisfied the above-mentioned value of 5 kJ/m ² or more. As a result, it was confirmed that the inorganic-containing polyolefin resin material of the present invention has no practical problems in both electrical communication properties and impact properties.

As described above, the inorganic-containing resin constituting the trough in the leaky coaxial cable installation structure is a polyolefin-based resin with a dielectric constant of 3.15 or less in the frequency band of 400 to 440 MHz, as measured by the capacitance method. If recycled resin is used, a communication method using a leaky coaxial cable installation structure with excellent communication characteristics can be obtained. In this way, by applying a material with a predetermined dielectric constant to the trough structure in the leaky coaxial cable installation structure, the connection between the leaky coaxial cable placed inside the trough structure and the on-board antenna of a train can be improved. It is possible to realize a communication method in which communication is performed in a frequency band of 400 MHz between the two. At this time, it is desirable that the wall thickness of the trough structure in which the leaky coaxial cable is housed is thin, and for example, it is desirable that the maximum wall thickness be 10 mm or less.

Furthermore, if the inorganic-containing resin constituting the trough in the leaky coaxial cable installation structure is an inorganic-containing polyolefin resin with a dielectric constant of 3.15 or less in the 400-440 MHz frequency band measured by capacitance method. , it is possible to obtain a communication system using a leaky coaxial cable installation structure with excellent communication characteristics. In this way, by applying a material with a predetermined dielectric constant to the trough structure in the leaky coaxial cable installation structure, the connection between the leaky coaxial cable placed inside the trough structure and the on-board antenna of a train can be improved. It is possible to realize a communication system that performs communication in a frequency band of 400 MHz between the two. Even in this case, as the trough structure is made of polyolefin resin containing inorganic substances, it is preferable that the wall thickness of the trough structure in which the leaky coaxial cable is housed is thin. For example, it is desirable that the maximum wall thickness is 10 mm or less. .

Furthermore, as the recycled polyolefin resin material containing the inorganic substance, it is possible to provide a trough body that not only satisfies a dielectric constant of 3.15 or less, but also satisfies a tensile strength of 20 MPa or more and a flexural modulus of 1000 MPa or more. become. Further, it is possible to obtain a molded body of a trough body that satisfies not only the flexural modulus as tensile strength and bending properties, but also the Charpy impact strength as impact properties of 5 kJ/m ² or more.

<Water absorption, corrosion resistance, and weather resistance tests regarding test materials B1, B2, and B3>
Similar to the measurement of the water absorption rate after water absorption at 23° C. for 24 hours performed on Test Material B, the same test was additionally conducted on Test Material B1, Test Material B2, and Test Material B3. As a result, all of the materials forming the trough body satisfied the water absorption rate of 0.15% or less after water absorption at 23° C. for 24 hours based on JIS K7209, which is equivalent to ASTM D570. Therefore, the trough body can be formed using any of the test materials.

In addition, similar to the test for test material B shown in Table 2, similar corrosion resistance tests were additionally conducted for test material B1, test material B2, and test material B3. As a result, all of the materials forming the trough body were immersed in a 24-hour immersion test at room temperature in accordance with JIS K7114. Seawater simulating liquid test of 30% CaCl ₂ immersion test and immersion test with a test liquid prepared by diluting a liquid mixture of H ₂ SO ₄ and HNO ₃ at a ratio of 2:1 to 1% concentration as an acid rain simulating liquid. The mass change rate in the snow melting agent simulation liquid test and the acid rain simulation liquid test was 0.10% or less. Therefore, it is possible to form the trough body from any polyolefin resin material.

Further, similar to the test for test material B shown in Table 3, similar tests were additionally conducted for test material B1, test material B2, and test material B3. As a result, the tensile strength of the material forming the trough body was determined by the tensile strength of polyolefin-based recycled resin after an accelerated weather resistance test in which UV light with an irradiation intensity of 90 mW/ ^cm2 was irradiated for 2,000 hours in an environment of 50% humidity. It was confirmed that the residual rate of the tensile strength was 95% or more of the tensile strength before irradiation with ultraviolet light, and the residual rate of Charpy impact value was 90% or more of the Charpy impact value before irradiation with ultraviolet light. Therefore, the trough body can be formed using any polyolefin resin material.

<Communication method with on-vehicle antenna using leaky coaxial cable installation structure>
As described above, by forming the resin material constituting the trough structure in the leaky coaxial cable installation structure with a polyolefin-based recycled resin containing an inorganic material with a dielectric constant of 3.15 or less in the frequency band of 400 to 440 MHz, the trough structure can be improved. To obtain a communication method using a leaky coaxial cable laying structure that allows good communication in a frequency band of 400 MHz between a leaky coaxial cable placed inside a structure and an antenna on a train car. be able to. Further, in this case, it is desirable that the maximum wall thickness of the trough structure is 10 mm or less. Good communication conditions can be obtained by setting the wall thickness of the trough structure to 10 mm or less.

In addition, the transmission loss is within ±2 dB/km compared to the case where the leaky coaxial cable is placed at a predetermined height and angle on a cable support member whose height is adjusted on concrete ground without using a trough structure. , it is possible to obtain a communication method using a leaky coaxial cable installation structure having communication characteristics in which the coupling loss is within ±2 dB.

<Communication system with on-vehicle antenna using leaky coaxial cable installation structure>
Furthermore, if the resin material constituting the trough structure in the leaky coaxial cable installation structure is a recycled polyolefin resin containing an inorganic substance with a dielectric constant of 3.15 or less in the frequency band of 400 to 440 MHz, the inside of the trough structure A communication system using a leaky coaxial cable installation structure that performs communication in a frequency band of 400 MHz between a mounted leaky coaxial cable and an antenna on a train vehicle can be obtained.

In addition, the transmission loss is within ±2 dB/km compared to the case where the leaky coaxial cable is placed at a predetermined height and angle on a cable support member whose height is adjusted on concrete ground without using a trough structure. , it is possible to obtain a communication system using a leaky coaxial cable installation structure, which has communication characteristics in which the coupling loss is within ±2 dB.

To summarize the above characteristics of the present invention, the leaky coaxial cable 5 is not exposed to the outside environment, but is placed on the cable support members 11, 11a, 11b in a closed space formed by a resin trough. Despite the arrangement, good communication characteristics were obtained without deterioration in transmission characteristics due to radio wave absorption by the resin trough. Therefore, the leakage coaxial cable 5 is prevented from being damaged by local bending fatigue due to wind pressure when a train passes, and durability is improved. Furthermore, since the leaky coaxial cable 5 does not deteriorate due to ultraviolet irradiation, a leaky coaxial cable installation structure that can dramatically extend the life of the leaky coaxial cable 5 is obtained.

In addition, in the present invention, since the leaky coaxial cable 5 is placed on the support part 33 of the cable support members 11, 11a, and 11b inside the trough 3, the leaky coaxial cable 5 may vibrate under the wind pressure of the train and leak. The surface of the coaxial cable 5 does not get wet due to rainwater or the like. Therefore, the communication characteristics of the radio waves transmitted from the leaky coaxial cable 5 are stabilized, and good communication characteristics can be obtained. Moreover, if the trough 3 is made of resin, unlike concrete, even if the surface of the trough 3 gets wet with rain, the trough 3 hardly absorbs rainwater, so that the communication characteristics are stabilized. Additionally, unlike concrete, resin troughs are lightweight, making them easier to install. Furthermore, since the leaky coaxial cable 5 is not exposed to the external environment, the influence of temperature changes in the external environment can be alleviated. Furthermore, since the leaky coaxial cable 5 is placed on the cable support members 11, 11a, and 11b, the influence of radio waves from the concrete ground can be alleviated.

Further, the leaky coaxial cable 5 may be bent and loosely arranged in a substantially S-shape on the cable support member 11a in the trough 3 so that continuous bent portions are formed alternately in the longitudinal direction. . By doing this, even if tension is applied to the leaky coaxial cable 5 due to external environmental temperature changes or earthquakes, it is possible to prevent the external conductor of the leaky coaxial cable 5 from breaking due to the tension. .

Further, at least a portion of the leaky coaxial cable 5 is tied to the cable support member 11b by the string-like fixing member 55 and fixed to the cable support member 11b, so that the leaky coaxial cable 5 can be reliably supported. . In addition, in at least some of the cable support members 11, 11a, 11b, a pressing body made of either a polyethylene foam sheet or a rubber molded body is placed on the top of the leaky coaxial cable 5 placed on the cable support members 11, 11a, 11b. By arranging 59a and 59b, the leaky coaxial cable 5 can be pressed by the pressing bodies 59a and 59b. Therefore, the leaky coaxial cable 5 placed on the cable support members 11, 11a, 11b can be stably fixed by the pressing force.

Furthermore, the trough is secured by an anchor bolt 43 inserted into an existing trough fixing bolt insertion hole 41 formed in the longitudinal direction of the trough body 3a and extending in the longitudinal direction of the trough body 3a. The main body 3a can be easily fixed to the concrete ground 35. Further, a trough fixing bolt insertion hole 41 is provided at an arbitrary position in a groove between mutually opposing ribs 37 that are formed at the widthwise center of the back surface of the bottom part 7 and have a predetermined length along the longitudinal direction of the trough body. may be formed. Even in this case, the trough body 3a can be fixed to the concrete ground 35 by the anchor bolts 43 inserted into the trough fixing bolt insertion holes 41. Therefore, even if the fixing position of the anchor nut 45 provided on the concrete ground 35 is slightly shifted, the trough main body 3a can be easily fixed.

According to the present invention, it is possible to keep the height and orientation of the slot constant, and it is possible to suppress the influence of wind from trains, water, pollution, etc., and it is possible to suppress environmental temperature changes and ultraviolet irradiation. It is possible to provide a leaky coaxial cable laying structure and a leaky coaxial cable laying method that can alleviate the deterioration of the cable caused by the leaky coaxial cable, and to realize a communication method and a communication system using the leaky coaxial cable laying structure.

Using the communication method and communication system described above, it is possible to perform good communication with the on-vehicle antenna . By using the communication method and communication system using the leaky coaxial cable installation structure of the present invention, it becomes possible to impart flame retardancy to the trough and to communicate with an on-vehicle antenna with low loss.

The embodiments of the present invention have been described above with reference to the attached drawings, focusing on the case where the trough length is 1 m, but the technical scope of the present invention is the embodiment described in the specification where the trough length is 1 m. It is not limited to , but can also be applied to other trough lengths. In addition to the above, it is clear that those skilled in the art can come up with various changes and modifications within the scope of the technical idea stated in the claims, and these naturally also come within the scope of the present invention. It is understood that it falls within the technical scope.

For example, it goes without saying that the configurations of each embodiment can be combined with each other.

1, 1a, 1b, 1c, 1d, 1e...Leaky coaxial cable laying structure 3...Trough 3a...Trough body 3b...Trough lid 5...Leaky coaxial cable 7...Bottom 9... ...Side wall portions 11, 11a, 11b......Cable support members 13a, 13b...Connection portion 15...Fixing fittings 17...Bolts 19...Inner conductor 21...Insulator 21a...... Insulator string 23...Slot 25...Outer conductor 27...Outer sheath 29...Support wire 31...Cable connection section 32...Terminal connection section 33...Support section 33a... Groove 34... Power feeding part 35... Concrete ground 37... Ribs 39a, 39b... Groove 41... Trough fixing bolt insertion hole 43... Anchor bolt 45... Anchor nut 47a, 47b ...Inner rib 49...Fixing part 51...Trough structure 53...Groove 55...String-like fixing members 59a, 59b...Press body 61...Notch

Claims (25)

A trough body and a trough lid made of resin;
a leaky coaxial cable accommodated in the trough body;
Equipped with
The trough body has a bottom portion and side wall portions standing up on both sides of the bottom portion, and is positioned at a predetermined position in the longitudinal direction of the trough in a closed space formed by the trough in which the trough lid is capped on the trough body. , a cable support member made of resin and/or rubber is arranged, and the leaky coaxial cable is placed on the support portion of the cable support member with the support wire facing downward;
The trough body has a substantially U-shaped cross section, and connecting portions are formed at one end and the other end of the trough body and the trough lid, respectively, and by connecting the respective connecting portions, It is possible to connect a plurality of the troughs,
Furthermore, in a trough structure formed by connecting a predetermined number of troughs each having a trough body and a trough lid that are adjacent to each other, a predetermined length of a longitudinal direction inside a closed space formed by the trough structure is provided. A plurality of the cable support members are arranged at predetermined intervals at the positions, and the cable support members are arranged at predetermined heights of the cable support members in any position. The leaky coaxial cable is placed on the part,
The support part of the cable support member is formed into a substantially semicircular shape so that the leaky coaxial cable can be accommodated, and the leaky coaxial cable is connected to the support part of the cable support member from the bottom of the trough. It is supported at a predetermined height and at a predetermined angle.
A leaky coaxial cable laying structure in which a trough fixing bolt insertion hole is provided in the bottom of the trough body, and the trough body is fixed to concrete ground by an anchor bolt inserted through the trough fixing bolt insertion hole. ,
A pair of ribs protruding downward and facing each other across a groove having a predetermined length along the longitudinal direction of the trough are formed in the widthwise center of the back surface of the bottom of the trough body,
The trough fixing bolt insertion hole is an existing trough fixing bolt insertion hole in the form of an elongated hole formed approximately at the center of the longitudinal direction and the width direction between the ribs and facing the longitudinal direction of the trough body, or When the trough body is fixed to the concrete ground by an anchor bolt inserted into any one of the trough fixing bolt insertion holes that can be formed at any position in the groove between the ribs. A leaky coaxial cable laying structure, characterized in that the formation position of the trough fixing bolt insertion hole can be adjusted to correspond to the fixing position of the anchor nut . By adjusting the connection angle of the connection part of the trough body in at least one of the left-right direction and the vertical direction, the longitudinal direction of the trough body can be adjusted by adjusting the bolt fixing position when inserting the anchor bolt into the trough fixing bolt insertion hole. 2. The leaky coaxial cable laying structure according to claim 1, wherein in addition to adjusting the distance between the formation positions, it is possible to adjust both the width direction and/or vertical direction displacement of the fixing position of the trough body. 3. The leaky coaxial cable laying structure according to claim 1 , wherein the cable support members are provided linearly at intervals of 2 m or more and 6 m or less of the trough structure. The support portions of at least some of the plurality of cable support members are formed at positions offset by a predetermined distance from the center of the cable support member in the width direction, and the leaky coaxial cable is offset from the center of the cable support member in the width direction. Continuous bent portions in the longitudinal direction of the trough structure are approximately formed alternately on the support portions of the cable support members arranged at positions offset from the center by a predetermined distance to the left and right alternately. The leaky coaxial cable installation structure according to any one of claims 1 to 3, characterized in that the leaky coaxial cable is curved in an S-shape and laid loose. The cable support member is formed integrally with the trough body at a predetermined position in the longitudinal direction of the trough body made of resin, or the cable support member is formed separately from the trough body, and the cable support member is formed separately from the trough body. A fixing part is formed on the inner side of the cross section, and the cable support member is fixed to the fixing part, and the fixing part is formed so that the cable support member can be inserted into and fixed to the inner surface of the trough body. The leaky coaxial according to any one of claims 1 to 4 , wherein the cable support member is inserted between the inner ribs and is fixed therebetween. Cable laying structure. At least a portion of the leaky coaxial cable placed on the cable support member is tied to the cable support member with a string-like fixing member, so that the leaky coaxial cable is prevented from deforming in cross section. The leaky coaxial cable installation structure according to any one of claims 1 to 5, wherein the leaky coaxial cable installation structure is fixed to a cable support member. Between the connection parts that interconnect the leaky coaxial cables, the farther the distance from the feeding point is, the more the arrangement angle of the slots of the leaky coaxial cables increases with respect to the cable axis direction at each predetermined interval of the leaky coaxial cables. 7. The leaky coaxial cable installation structure according to claim 1 , wherein the slots are arranged at small intervals so that the slots become large or the slots are densely packed. According to any one of claims 1 to 7 , the connection portion that connects the leaky coaxial cables to each other is arranged at a position other than the arrangement portion of the cable support member of the trough structure. leaky coaxial cable installation structure. The resin forming the trough structure has a dielectric constant of 3.15 or less in a frequency band of 400 to 440 MHz measured by a capacitance method, and the maximum dielectric constant of the trough lid and the trough body forming the trough structure is The wall thickness is 10 mm or less, and the water absorption of the resin forming the leaky coaxial cable installation structure satisfies the water absorption rate of 0.15% or less after 24 hours of water absorption at 23°C, based on JIS K7209, which is equivalent to ASTM D570. The leaky coaxial cable installation structure according to any one of claims 1 to 8, wherein the leaky coaxial cable installation structure is characterized in that: The leaky coaxial cable is placed at a predetermined height on the cable support member made of resin inside the closed space formed by the trough structure formed by connecting the troughs in which the trough body is covered with the trough lid. The communication characteristics under the predetermined conditions in the 400 to 440 MHz band when placed at a predetermined angle are as follows: The leaky coaxial cable is placed at a predetermined height on the cable support member placed on the concrete ground without the trough structure. The leaky coaxial cable installation according to claim 9 , characterized in that the leaky coaxial cable has communication characteristics in which transmission loss is within ±2 dB/km and coupling loss is within ±2 dB when compared with a case where the cable is placed at a predetermined angle. structure. The leaky coaxial cable is placed at a predetermined height on the cable support member made of resin inside the closed space formed by the trough structure formed by connecting the troughs in which the trough body is covered with the trough lid. As a test result of a communication characteristic confirmation test in the 400 to 440 MHz band of the trough structure when placed at a predetermined angle , the trough structure has the outer and inner surfaces of the trough structure wetted with water to absorb water. Even when the cable is used, communication characteristics equivalent to those obtained when the outer and inner surfaces of the trough structure are dry can be obtained, and furthermore, when the cable is height-adjusted above the concrete ground without the trough structure, It is characterized by having communication characteristics in which transmission loss is within ±2 dB/km and coupling loss is within ±2 dB when compared to when the leaky coaxial cable is placed on a support member at a predetermined height and at a predetermined angle. The leaky coaxial cable installation structure according to claim 9 . 12. The leaky coaxial cable installation structure according to claim 1, wherein the resin material forming the trough structure is a recycled polyolefin resin containing an inorganic substance or a polyolefin resin containing an inorganic substance. A resin trough body having a bottom portion and side walls standing up on both sides of the bottom portion and having a substantially U-shaped cross section, connected to one end and the other end of the trough body and the trough lid, respectively. a plurality of troughs are formed, and it is possible to connect a plurality of troughs by connecting each of the connection parts,
In a closed space formed by a trough in which the trough body is covered with the trough lid, a cable support member is disposed at a predetermined position in the longitudinal direction of the trough, and a leaky coaxial cable is attached to the support portion of the cable support member. can be placed,
A trough fixing bolt insertion hole is provided in the bottom of the trough body, and the trough body is fixed to the concrete ground by an anchor bolt inserted into the trough fixing bolt insertion hole to accommodate the leaky coaxial cable. In the trough body,
A pair of ribs protruding downward and facing each other across a groove having a predetermined length along the longitudinal direction of the trough are formed in the widthwise center of the back surface of the bottom of the trough body,
The trough fixing bolt insertion hole is an existing elongated hole-shaped trough fixing bolt insertion hole formed approximately at the center of the longitudinal direction and the width direction between the ribs and facing the longitudinal direction of the trough body, or When the trough body is fixed to the concrete ground by the anchor bolt inserted into any one of the trough fixing bolt insertion holes that can be formed at any position in the groove between the ribs. A trough body for storing a leaky coaxial cable, characterized in that the formation position of the trough fixing bolt insertion hole can be adjusted to correspond to the fixing position of the anchor nut. By adjusting the connection angle of the connection part of the trough body in at least one of the left-right direction and the vertical direction, the longitudinal direction of the trough body is adjusted by adjusting the bolt fixing position when inserting the anchor bolt into the trough fixing bolt insertion hole. 14. The leaky coaxial cable according to claim 13, wherein in addition to adjusting the distance between the formation positions of the trough body, it is possible to adjust both the displacement of the fixing position in the width direction and/or the vertical direction of the trough body. The trough body for storage. The cable support member is formed integrally with the trough body at a predetermined position in the longitudinal direction inside the cross section of the trough body, or the cable support member is inserted into and fixed to the inner surface of the trough body. The trough body for storing a leaky coaxial cable according to claim 13 or 14, characterized in that inner ribs are formed that face each other. By providing an anchor nut insertion hole instead of providing the trough fixing bolt insertion hole at either position of the existing trough fixing bolt insertion hole of the trough body and the groove between the pair of ribs, The trough body for storing a leaky coaxial cable according to any one of claims 13 to 15, characterized in that the trough body has a structure that can be fixed with an anchor bolt provided in concrete ground. The trough body has mechanical properties such as a tensile strength of 20 MPa or more, a flexural modulus of 1000 MPa or more, and a Charpy impact value of 5 kJ/m ² or more as measured by a Charpy impact test based on JIS K7111 . have,
Furthermore, after an accelerated weather resistance test in which UV light with an irradiation intensity of 90 mW/cm ² is irradiated for 2000 hours in an environment of 50% humidity, the residual tensile strength of the resin forming the trough body is The tensile strength is 95% or more of the tensile strength before irradiation with light, and the residual percentage of Charpy impact value after irradiation with ultraviolet light is 90% or more of the Charpy impact value before irradiation with ultraviolet light. A trough body housing the leaky coaxial cable according to claim 16. The trough body has a water absorption rate of 0.15% or less after water absorption at 23°C for 24 hours, as measured based on JISK7209, which is equivalent to ASTM D570 , and is further immersed for 24 hours at room temperature in accordance with JISK7114. In the test, an immersion test was conducted with a 3% NaCl aqueous solution as a seawater simulating liquid, a 30% CaCl ₂ immersion test as a snow melting agent simulating liquid, and a 2:1 ratio of H ₂ SO ₄ and HNO ₃ as an acid rain simulating liquid. The mass change rate of the resin forming the trough body in an immersion test using a test liquid obtained by diluting the mixed liquid to a concentration of 1% is 0.1% or less in all tests. A trough body for housing the leaky coaxial cable according to any one of claims 13 to 17 . A method of laying a leaky coaxial cable, the method comprising:
fixing a resin trough body having a substantially U-shaped cross section and having a bottom portion and side wall portions standing on both sides of the bottom portion to concrete ground;
arranging a cable support member inside the trough body, and arranging a leaky coaxial cable in the support portion of the cable support member with the support wire facing downward;
Equipped with
In the step of fixing to the concrete ground,
In the leaky coaxial cable laying method , the bottom of the trough body is provided with a trough fixing bolt insertion hole, and the trough body is fixed to concrete ground by an anchor bolt inserted through the trough fixing bolt insertion hole. ,
A pair of ribs protruding downward and facing each other across a groove having a predetermined length along the longitudinal direction of the trough are formed in the widthwise center of the back surface of the bottom of the trough body,
The trough fixing bolt insertion hole is an existing trough fixing bolt insertion hole in the form of an elongated hole formed approximately at the center of the longitudinal direction and the width direction between the ribs and facing the longitudinal direction of the trough body, or When the trough body is fixed to the concrete ground by an anchor bolt inserted into any one of the trough fixing bolt insertion holes that can be formed at any position in the groove between the ribs. . A method for laying a leaky coaxial cable, characterized in that the formation position of the trough fixing bolt insertion hole can be adjusted to correspond to the fixing position of the anchor nut . In the step of fixing the trough body to the concrete ground, connection portions are formed at one end and the other end of the trough body, and the connection portions are connected to each other at a predetermined angle in the left-right direction and/or the up-down direction. 20. The method for laying a leaky coaxial cable according to claim 19 , wherein the leaky coaxial cable can be laid so as to absorb displacement of the formation position of the anchor nut provided in the concrete ground by connecting the cable at an angle of . . arranging the cable support member inside the trough body, and arranging the leaky coaxial cable in the support portion of the cable support member with the support wire facing downward;
The cable support member has a support portion formed at the center of the cable support member, and the cable support member is arranged at predetermined intervals at predetermined positions in the longitudinal direction of a trough structure in which a plurality of troughs are connected. By setting
21. The method of laying a leaky coaxial cable according to claim 19, further comprising the step of linearly arranging the leaky coaxial cable on a support section on the cable support member. In the step of arranging the cable support member inside the trough body and arranging the leaky coaxial cable in the support portion of the cable support member with the support wire facing downward, the cable support member The support portion of the member is formed offset by a predetermined distance from the center of the cable support member, and the adjacent cable support members are alternately arranged inverted, so that the leaky coaxial cable is separated from the support portion on the cable support member. 21. The method of laying a leaky coaxial cable according to claim 19 or 20, further comprising the step of loosely arranging the leaky coaxial cable in a substantially S-shape. In the step of fixing to the concrete ground,
Any one of claims 19 to 22, wherein an anchor nut insertion hole is provided in the bottom of the trough body instead of a trough fixing bolt insertion hole, and an anchor bolt is provided in the concrete ground. How to lay a leaky coaxial cable as described in the above . In the leaky coaxial cable installation structure according to any one of claims 1 to 8, the resin material containing an inorganic substance constituting the trough structure is a polyolefin-based resin material having a dielectric constant of 3.15 or less in a frequency band of 400 to 440 MHz. It is recycled resin,
The polyolefin recycled resin has a tensile strength of 20 MPa or more, a flexural modulus of 1000 MPa or more, and a Charpy impact value of 5 kJ/m ² or more as determined by a Charpy impact test based on JIS K7111 . can be,
The dielectric constant satisfies 3.15 or less, and the maximum wall thickness is formed to be 10 mm or less,
Based on JIS K7209, the water absorption rate after water absorption for 24 hours at 23°C satisfies 0.15% or less. A communication method that communicates using frequency bands.
When communicating using a network analyzer or spectrum analyzer using a half-wavelength dipole antenna installed at a height of 1.5 m directly above the leaky coaxial cable, if the trough surface is dry or the outer and inner surfaces of the trough In any state, such as when wet with water and allowed to absorb water,
The transmission loss is within ±2 dB/km in comparison with the case where the leaky coaxial cable is placed at a predetermined height and at a predetermined angle on the cable support member whose height is adjusted on the concrete ground without using the trough structure. A communication method using a leaky coaxial cable installation structure, characterized in that it is possible to obtain communication characteristics in which the coupling loss is within ±2 dB. The leaky coaxial cable laying structure according to any one of claims 1 to 8 is used, and the resin material containing an inorganic substance constituting the trough structure in the leaky coaxial cable laying structure is dielectric in a frequency band of 400 to 440 MHz. It is a polyolefin-based recycled resin with a ratio of 3.15 or less,
The polyolefin recycled resin has a tensile strength of 20 MPa or more, a flexural modulus of 1000 MPa or more, and a Charpy impact value of 5 kJ/m ² or more as determined by a Charpy impact test based on JIS K7111 . can be,
The trough structure has a dielectric constant of 3.15 or less, a maximum wall thickness of 10 mm or less, and a water absorption rate of 0.15% or less after water absorption at 23°C for 24 hours based on JIS K7209. A communication system that communicates in the 400MHz frequency band between a leaky coaxial cable installed inside the train and an antenna on the train car.
When communicating using a network analyzer or spectrum analyzer using a half-wavelength dipole antenna installed at a height of 1.5 m directly above the leaky coaxial cable,
In any state where the trough surface is dry or the outer and inner surfaces of the trough are wetted with water to absorb water,
In comparison with the case where the leaky coaxial cable is placed at a predetermined height and at a predetermined angle on the cable support member whose height is adjusted on concrete ground without using the trough structure, the transmission loss is ±2 dB/km. A communication system using a leaky coaxial cable installation structure, characterized in that it is possible to obtain communication characteristics with a coupling loss within ±2 dB.

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