JP4113202B2 - Radio wave absorption structure - Google Patents

Description

  The present invention relates to a radio wave absorption structure.

There is a wireless LAN system using radio waves as a technology for exchanging data with a plurality of terminals (computers, mobile phones, mobile terminals, etc.) arranged in a room and peripheral devices.
Conventionally, since the number of computers, mobile phones, mobile terminals and their peripheral devices is small, sufficient information communication has been performed even if there are few installation points (access points) in the antenna for the wireless LAN.
In recent years, the number of computers, mobile phones, mobile terminals, and peripheral devices installed has rapidly increased, and it has become necessary to increase the number of antenna installation points (access points) to cope with them.
However, simply increasing the number of antenna installation locations (access points) does not provide an optimal radio wave environment for information communication using a wireless LAN, and various operations such as radio wave interference, delay, and malfunction due to unnecessary reflected waves. A problem occurred. Therefore, although a directional antenna that can change the directionality of transmission is used (for example, see Patent Documents 1 and 2), the radio wave environment of information communication by wireless LAN has not yet been optimized. It is.
JP 2005-45494 A JP 2004-180038 A

In addition, since a directional antenna has complicated functions such as a sensor and a control circuit, it cannot be easily manufactured. Furthermore, if an omnidirectional antenna is already installed, the antenna Since it had to be replaced and installed, it was time consuming and expensive to replace.
Accordingly, an object of the present invention is to provide a radio wave absorption structure that has a simple structure and can adjust the range of radio waves emitted from an antenna.

In order to achieve the above object, a radio wave absorption structure according to the present invention includes an antenna that transmits and / or receives data to and from a terminal, and the antenna includes an radio wave absorber and an opening). The radio wave absorber that surrounds the antenna cover and that forms the antenna cover has a two-layer structure in which a box-shaped inner layer is fitted into a box-shaped outer layer, and the inner layer has a plurality of conductive films. The outer layer is formed by tangling a plurality of types of fibers having a conductive film, and the average density of the inner layer is the above. The antenna is set to be smaller than the average density of the outer layer, and the antenna is attached to the bottom surface of the box-shaped inner layer that forms the storage chamber of the antenna cover in which the antenna is stored. It is those that form.

In addition, an antenna for transmitting and / or receiving data to and from a terminal is provided, and the antenna is surrounded by an antenna cover made of a radio wave absorber and having an opening, and the radio wave absorption forming the antenna cover. The body is a two-layer structure in which a box-shaped inner layer is fitted into a box-shaped outer layer, and the inner layer is formed by entwining a large number of fibers of a single thickness having a conductive coating, The outer layer is formed by entwining a large number of single-thick fibers having a conductive coating, and the average thickness of the coating of the inner layer is smaller than the average thickness of the coating of the outer layer. In addition, the antenna is mounted on the bottom side of the box-shaped inner layer that forms the storage chamber of the antenna cover in which the antenna is stored.

The antenna is attached to the main body of the access point for the wireless LAN, and the main body is directly attached to the bottom surface of the inner layer, and the antenna and the main body are stored in the storage chamber . .

The inner layer is formed so that the fiber density increases from the inner surface side toward the bonding surface side with the outer layer, and the outer layer has a fiber density from the bonding surface side with the inner layer toward the outer surface side. Is formed to be large. Alternatively, the inner layer is formed so that the thickness dimension of the coating film of the fiber increases from the inner surface side toward the bonding surface side with the outer layer, and the outer layer is formed from the bonding surface side with the inner layer to the outer surface side. The fiber coating is formed so that the thickness dimension of the fiber increases.

The present invention has the following remarkable effects.
According to the radio wave absorption structure according to the present invention, the range of radio waves transmitted and / or received by the antenna can be adjusted. In other words, since the antenna cover reliably absorbs radio waves that are spread out of the predetermined range from the antenna, the antenna can be adjusted to the direction (range) of the corresponding terminal and can be accurately transmitted.
Therefore, even when a plurality of antennas are installed in a room, it is possible to prevent radio waves transmitted and received from interfering (mutual interference) and to increase the number of antennas and terminals that can be installed in a certain space.
Further, the structure of the antenna cover is simple, and furthermore, since it can be easily attached to an existing antenna, it is possible to reduce the cost and work burden related to manufacturing and installation (attachment).

Hereinafter, the present invention will be described in detail with reference to the drawings illustrating embodiments.
In the first embodiment of the present invention, as shown in FIG. 1, reference numeral 10 denotes a terminal (computer or the like) arranged indoors, and an access point (wireless LAN) ( A radio wave repeater 9 is attached. The access point 9 includes a main body 14 having a signal conversion device and the like, and an antenna 1 that transmits and / or receives data between the terminal 10. The antenna 1 is suspended (attached) on the lower surface of the main body 14. Further, the antenna 1 and the main body 14 are surrounded by the antenna cover 2. A plurality of access points 9 and terminals 10 are installed in the room. However, in FIG.

  In FIG. 2, the antenna cover 2 is composed of a radio wave absorber 3 and is formed in a box shape having an opening 6. The antenna cover 2 is attached to the ceiling 13 at the back surface (upper surface of the outer wall) 15 and is disposed with the opening 6 facing downward. A storage chamber 16 is formed in the antenna cover 2, and an access point 9 (the main body 14 and the antenna 1) is stored in the storage chamber 16. The access point 9 is attached to a bottom surface (inner wall upper surface) 21 that forms the storage chamber 16. The radio wave absorber 3 is formed in a two-layer structure in which an inner layer 11 and an outer layer 12 are laminated.

3 and 4, the inner layer 11 and the outer layer 12 of the radio wave absorber 3 are formed by entwining a plurality of fibers 4 having a plurality of types of thickness having a conductive coating 5. As shown in FIG. 4 (A), the inner layer 11 and the outer layer 12 are formed of a mat-like fiber assembly F in which fibers 4 of a plurality of types are randomly entangled, and the inner layer 11 and the outer layer 12 are each 5 The mat-like fiber assemblies F are combined in a box shape having an opening 6 and bonded with an adhesive (see FIGS. 2 and 3). The inner layer 11 formed in a box shape is fitted in the box-shaped outer layer 12 and bonded with an adhesive.
The inner layer 11 is formed so that the density of the fibers 4 increases from the inner surface 17 side toward the bonding surface 19 side with the outer layer 12. In addition, the outer layer 12 is formed so that the density of the fibers 4 increases from the joint surface 20 side with the inner layer 11 toward the outer surface 18 side.
Further, the average density of the fibers 4 in the inner layer 11 and the outer layer 12 is set differently, and the average density of the inner layer 11 is set to be smaller than the average density of the outer layer 12. The average density of the fibers 4 is an average value of the density of the fibers 4 for each of the inner layer 11 and the outer layer 12 (for each fiber assembly F).

Examples of the mat-like fiber assembly F of the radio wave absorber 3 and the manufacturing method thereof will be specifically described.
The fibers 4 of the fiber assembly F are made of organic fibers (fibers made of resin) or inorganic fibers (glass fibers / metal fibers). Then, 100 parts by weight of the 1000 denier fiber 4, 50 parts by weight of the 500 denier fiber 4, and 20 parts by weight of the 10 denier fiber 4 are produced, and the fibers 4 of various thicknesses are randomly entangled. It is formed in a mat shape so that the density of the material changes continuously in a certain direction (thickness direction). Then, an adhesive is spray applied so that the entangled fibers 4 are not loosened, and the fibers 4 are bonded and fixed. Thereafter, a carbon paint (conductive material) is spray applied onto the entangled fibers 4 and dried. And as shown in FIG.4 (B), the manufacture of the fiber assembly F is completed by forming the carbon thin film (coating 5) of fixed thickness in the fiber 4. As shown in FIG.
The thickness dimension of the fiber assembly F is set to 25 mm. In addition, as a raw material of the fiber 4, it is preferable that it is an inorganic fiber at the point of nonflammability.

In addition, when the frequency of the radio wave emitted from the antenna 1 is 2.4 GHz band or 5.2 GHz band, the radio wave absorber 3 has a radio wave reflection attenuation of 15 dB or more in the TE wave / TM wave, The transmission attenuation is set to 20 dB or more.
The radio wave return loss is the amount of radio wave reflected by the radio wave absorber 3 (released from the antenna 1) and absorbed by the radio wave absorber 3. That is, the radio wave return loss = ( (Incident radio wave amount) − (reflected radio wave amount). The radio wave transmission attenuation is the amount of radio waves that are absorbed by the radio wave absorber 3 through the radio wave absorber 3 (released from the antenna 1), that is, the radio wave transmission attenuation = ( (Incident radio wave amount) − (transmitted radio wave amount).

Next, in the second embodiment of the present invention, as shown in FIGS. 1 to 3, the access point 9 having the antenna 1 is a box type comprising the radio wave absorber 3 as in the first embodiment. The radio wave absorber 3 is formed in a two-layer structure in which an inner layer 11 and an outer layer 12 are laminated. Hereinafter, a configuration in which the second embodiment is different from the first embodiment will be described.
Although not shown, the inner layer 11 and the outer layer 12 of the radio wave absorber 3 are formed of a plurality of mat-like fiber assemblies F, and the fiber assemblies F (the inner layer 11 and the outer layer 12) are made of a conductive coating 5. Are formed by entanglement of a large number of fibers 4 having a single thickness.
The inner layer 11 is formed so that the thickness dimension of the coating 5 of the fibers 4 increases from the inner surface 17 side toward the joint surface 19 side with the outer layer 12. The outer layer 12 is formed so that the thickness dimension of the coating 5 of the fibers 4 increases from the joint surface 20 side with the inner layer 11 toward the outer surface 18 side.
Furthermore, the average thickness dimensions of the coating 5 of the inner layer 11 and the outer layer 12 are set differently so that the average thickness dimension of the coating 5 of the inner layer 11 is smaller than the average thickness dimension of the coating 5 of the outer layer 12. Is set to In addition, the average thickness dimension of the coating 5 is an average value of the thickness dimension of the coating 5 included in the fibers 4 for each of the inner layer 11 and the outer layer 12 (for each fiber assembly F).
The density of the fibers 4 in the inner layer 11 and the outer layer 12 is uniform.

In the method of manufacturing the mat-like fiber assembly F, first, a large number of fibers 4 having a thickness of 1000 denier are randomly entangled to form a mat shape, and a conductive material is applied to the fibers 4. Next, the mat-like fibers 4 are attached to a rotating machine, and the thickness of the conductive material applied by the centrifugal force is adjusted so as to continuously change in a certain direction (thickness direction), and dried.
The thickness dimension of the fiber assembly F is set to 25 mm.
In the second embodiment, the configuration other than the above description is the same as the configuration of the first embodiment, and a description thereof will be omitted .

Contact name in that wave absorption rate is improved, the wave absorber 3 having a two-layer structure is also good preferred, than one layer structure, be a two-layer structure, compactness, workability, assembling good Masui also from the point of view.

The antenna 1 included in the radio wave absorption structure according to the present invention may be a non-directional antenna or a directional antenna. In particular, when the omni-directional antenna is applied, the direction of the emitted radio wave. The effect of adjusting (range) is exhibited. Further, the antenna 1 may be any one of transmitting data, receiving only, and transmitting / receiving data with the terminal 10.
The antenna cover 2 may be formed by attaching a resin or metal reinforcing plate to the outer surface 8 of the radio wave absorber 3 .
Name your, access point 9 and the antenna cover 2, it may be installed on a wall or the like other than the ceiling 13.

The use method (action) of the above-described radio wave absorption structure according to the present invention will be described.
In FIG. 3, when the antenna 1 is an omnidirectional antenna, radio waves are emitted from the antenna 1 so as to be scattered around (in the direction of the arrow). Of the emitted radio waves, the radio waves emitted toward the antenna cover 2 are absorbed by the radio wave absorber 3 of the antenna cover 2. Specifically, the radio wave reflected by the cover 2 is attenuated (weakened) after being incident on the radio wave absorber 3 and reflected, and the radio wave transmitted through the cover 2 is attenuated after being incident on the radio wave absorber 3 ( Weakened)
From the opening 6 of the antenna cover 2, radio waves are emitted from the antenna 1 toward the terminal 10 without being weakened. That is, the radio wave from the antenna 1 is emitted as it is in the area A (between the two dashed lines) shown in FIG. 3, and there is only a weak radio wave that passes through the antenna cover 2 in the area B outside the area A. do not do.

As described above, the radio wave absorption structure of the present invention includes the antenna 1 that transmits and / or receives data to and from the terminal 10, and the antenna 1 includes the radio wave absorber 3 and has the opening 6. Since it is surrounded by the antenna cover 2, the range of radio waves transmitted and / or received by the antenna 1 can be adjusted. That is, since the antenna cover 2 reliably absorbs radio waves that spread from the antenna 1 outside the predetermined range, the antenna 1 can adjust the direction (range) of the corresponding terminal 10 and send radio waves accurately. . In particular, when the antenna 1 is an omnidirectional antenna, the direction in which radio waves are transmitted and received can be adjusted effectively.
Therefore, even if a plurality of antennas 1 are installed in the room, it is possible to prevent radio waves transmitted and received from crossing (mutual interference), and to increase the number of antennas 1 and terminals 10 that can be installed in a certain space. Can do.
Moreover, since the structure of the antenna cover 2 is simple and can be easily attached to the existing antenna 1, it is possible to reduce the cost and work load related to manufacturing and installation (attachment).

Further, the radio wave absorber 3 is formed by entwining a large number of fibers 4 of a plurality of types having a conductive coating 5 and the fibers 4 from the inner surface 7 side to the outer surface 8 side of the radio wave absorber 3. Therefore, the radio wave absorber 3 can sufficiently absorb the radio wave emitted from the antenna 1.
Since the outer surface 8 in which the density of the fibers 4 of the radio wave absorber 3 is increased reflects the radio wave, it is not necessary to form a reflection layer on the outer surface 8 side, and the manufacturing can be easily performed.

In addition, the radio wave absorber 3 is formed by entwining a large number of single-sized fibers 4 having a conductive coating 5 and the fibers 4 from the inner surface 7 side to the outer surface 8 side of the radio wave absorber 3. Since the thickness dimension of the coating 5 is set to be thick, the radio wave absorber 3 can sufficiently absorb radio waves emitted from the antenna 1.
Since the outer surface 8 in which the density of the fibers 4 of the radio wave absorber 3 is increased reflects the radio wave, it is not necessary to form a reflection layer on the outer surface 8 side, and the manufacturing can be easily performed.

In addition, an antenna 1 that transmits and / or receives data to and from the terminal 10 is provided, and the antenna 1 is surrounded by an antenna cover 2 that includes the radio wave absorber 3 and has an opening 6. 3 is formed by laminating a plurality of mat-like fiber assemblies F from the inner surface 7 side toward the outer surface 8 side, so that the range of radio waves transmitted and / or received by the antenna 1 can be adjusted. . That is, since the antenna cover 2 reliably absorbs radio waves that spread from the antenna 1 outside the predetermined range, the antenna 1 can adjust the direction (range) of the corresponding terminal 10 and send radio waves accurately. . In particular, when the antenna 1 is an omnidirectional antenna, the direction in which radio waves are transmitted and received can be adjusted effectively.
Therefore, even if a plurality of antennas 1 are installed in the room, it is possible to prevent radio waves transmitted and received from crossing (mutual interference), and to increase the number of antennas 1 and terminals 10 that can be installed in a certain space. Can do.
Furthermore, since the radio wave absorber 3 is formed by laminating a plurality of fiber assemblies F, the radio wave absorption rate can be further improved.
Moreover, since the structure of the antenna cover 2 is simple and can be easily attached to the existing antenna 1, it is possible to reduce the cost and work load related to manufacturing and installation (attachment).

  Further, a plurality of mat-like fiber aggregates F forming the radio wave absorber 3 are formed by entwining a large number of fibers 4 having a conductive coating 5, and the fibers 4 have different average densities. Since the aggregate F is laminated and arranged so that the average density of the fibers 4 increases from the inner surface 7 side to the outer surface 8 side of the radio wave absorber 3, the radio wave absorber 3 absorbs broadband radio waves. And the radio wave absorption rate can be further improved.

  Further, the plurality of mat-like fiber aggregates F forming the radio wave absorber 3 are formed by entwining many fibers 4 having the conductive coating 5, and the difference in the average thickness of the conductive coating 5 is different. Since the plurality of fiber assemblies F are arranged so that the average thickness dimension of the coating 5 increases from the inner surface 7 side to the outer surface 8 side of the radio wave absorber 3, the radio wave absorber 3 has a wide bandwidth. Radio waves can be absorbed, and the radio wave absorption rate can be further improved.

  Further, since the antenna 1 is attached to the main body 14 of the access point 9 for wireless LAN and the antenna 1 and the main body 14 are surrounded by the antenna cover 2, even if a plurality of antennas 1 are installed indoors, A wireless LAN system that does not cause interference (mutual interference) can be constructed. Moreover, since it can be easily attached to the existing antenna 1 (access point 9), it is possible to reduce the cost and work load related to installation (attachment).

It is a front view which shows the 1st Embodiment of this invention. It is a perspective view which shows an installation state. It is a cross-sectional front view. It is explanatory drawing of an electromagnetic wave absorber, Comprising: (A) is a perspective explanatory drawing, (B) is principal part expanded sectional explanatory drawing .

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Antenna 2 Antenna cover 3 Wave absorber 4 Fiber 5 Coating 6 Opening 7 Inner surface 8 Outer surface 9 Access point
10 terminal
11 Inner layer
12 outer layer
14 Body
16 Storage room
17 Inside
18 Exterior
19, 20 Joint surface
21 Bottom F Fiber assembly

Claims (5)

An antenna cover (1) having an antenna (1) for transmitting and / or receiving data to and from the terminal (10), the antenna (1) comprising an electromagnetic wave absorber (3) and having an opening (6) 2) and the electromagnetic wave absorber (3) forming the antenna cover (2) has a two-layer structure in which a box-shaped inner layer (11) is fitted into a box-shaped outer layer (12), The inner layer (11) is formed by entwining a plurality of fibers (4) having a plurality of thicknesses having a conductive coating (5), and the outer layer (12) is formed of a conductive coating (5). A plurality of types of fibers (4) having a plurality of thicknesses are entangled, and the average density of the inner layer (11) is set to be smaller than the average density of the outer layer (12), and Form the storage compartment (16) of the antenna cover (2) where the antenna (1) is stored. A radio wave absorption structure characterized in that the antenna (1) is attached to the bottom side of the box-shaped inner layer (11) formed . An antenna cover (1) having an antenna (1) for transmitting and / or receiving data to and from the terminal (10), the antenna (1) comprising an electromagnetic wave absorber (3) and having an opening (6) 2) and the electromagnetic wave absorber (3) forming the antenna cover (2) has a two-layer structure in which a box-shaped inner layer (11) is fitted into a box-shaped outer layer (12), The inner layer (11) is formed by entwining a plurality of single-thick fibers (4) having a conductive coating (5), and the outer layer (12) is formed of a conductive coating (5). A plurality of fibers (4) having a single thickness having a mean thickness dimension of the coating (5) of the inner layer (11) is the coating (5) of the outer layer (12). Is set to be smaller than the average thickness dimension of the antenna, and the antenna (1) is accommodated in the antenna. The bottom side of the cover (2) of the inner layer of the housing chamber portion (16) box-shaped form (11), the radio wave absorber structure which is characterized by being configured to attach the antenna (1). The antenna (1) is attached to the main body (14) of the access point (9) for wireless LAN, and the main body (14) is directly attached to the bottom surface of the inner layer (11). The radio wave absorption structure according to claim 1 or 2, wherein the antenna (1) and the main body (14) are accommodated in (16) . The inner layer (11) is formed so that the density of the fibers (4) increases from the inner surface (17) side toward the joint surface (19) side with the outer layer (12), and the outer layer (12) The radio wave absorption structure according to claim 1, wherein the density of the fibers (4) increases from the side of the joint surface (20) with the inner layer (11) toward the outer surface (18) . The inner layer (11) is formed so that the thickness dimension of the coating (5) of the fiber (4) increases from the inner surface (17) side toward the joint surface (19) side with the outer layer (12), And the said outer layer (12) is formed so that the thickness dimension of the film (5) of a fiber (4) may become thick toward the outer surface (18) side from the joint surface (20) side with an inner layer (11). The radio wave absorption structure according to claim 2 .

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