JP3944038B2 - Twin loop antenna - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a twin loop antenna.
[0002]
[Prior art]
FIG. 8 is an external perspective view showing a conventional example of a dual loop antenna.
[0003]
This double loop antenna 1 has the same 2L double loop antenna elements (double loop antenna elements) 8, 9 in which four loops 2, 3, 4, 5 are connected by two parallel two lines 6a, 6b, 7a, 7b. Support member 11, 12, 13, 14 on one surface side (front side in the figure) of the reflector 10, so that the loop surface is parallel to the reflector 10 and the two loop antenna elements 8, 9 are arranged in tandem. Each is a 2L two-stage double loop antenna supported.
[0004]
A feed line 19 of the balun 15 is provided in the vicinity of the support members 11 and 12 so as to face the support members 11 and 12, and a feed line 20 of the balun 16 is provided in the vicinity of the support members 13 and 14. It is provided to face. That is, the balun 15 is composed of the support members 11 and 12 and the feed line 19, and the balun 16 is composed of the support members 13 and 14 and the feed line 20.
[0005]
Both the baluns 15 and 16 are connected to a coaxial feeder 17 disposed on the other surface side (the back side in the figure) of the reflector 10. The coaxial feeder 17 has an inner conductor, an insulator provided on the outer periphery of the inner conductor, and an outer conductor provided on the outer periphery of the insulator (not shown). A feeding point 18 is disposed in the center of the coaxial feeding line 17.
[0006]
When power from a transmitter (not shown) is supplied to the feed point 18 of the double loop antenna 1, power is distributed to both sides (left and right in the figure) of the coaxial feed line 17, and the baluns 15 and 16 are respectively connected from unbalanced lines. It is converted into a balanced line and reaches the double loop antenna elements 8 and 9 respectively, and radio waves are radiated from both the double loop antenna elements 8 and 9 in a direction perpendicular to the reflector 10 (in this case, on the upper side) (for example, Japanese Patent Application 2002). -See 129826).
[0007]
In some cases, the coaxial power supply line 17 is disposed on one surface side of the reflecting plate 10.
[0008]
[Problems to be solved by the invention]
By the way, in order to arrange the conventional double loop antenna 1 shown in FIG. 8 so that the reflector 10 is vertical and adjust the horizontal plane beam width to be within a desired angle range, loops 2 to 5 are used. There are methods of changing the distance from the reflecting plate 10 or changing the area of the reflecting plate 10. In particular, in order to reduce the horizontal plane beam width, it is often necessary to increase the area of the reflecting plate 10 to increase the aperture area. However, when the area of the reflector 10 is increased, there is a problem that the wind receiving load increases. In addition, when the area of the reflector 10 is increased, the protrusion distance from the steel tower to the twin-loop antenna 1 must be increased when the double-loop antenna 1 is arranged on a steel tower or the like, and as a result, the horizontal plane synthetic directivity is increased. There has been a problem that it is difficult to obtain omnidirectionality due to a large drop in electric field strength other than the antenna front direction (upward in the figure).
[0009]
Accordingly, an object of the present invention is to solve the above-described problems and provide a double loop antenna capable of adjusting the horizontal plane beam width without increasing the area of the reflector.
[0010]
[Means for Solving the Problems]
In order to achieve the above object, the invention of claim 1 is directed to a plurality of double-loop antenna elements in which two loops are connected by parallel two lines, a reflector, the reflector and the loop surface are parallel, and each double-loop. A dual-loop antenna comprising a support member that supports the dual-loop antenna element on the reflector so that the antenna elements are arranged in a column, wherein at least loops at both ends of the plurality of loops and the reflector And between the position where the loop is connected to the two parallel lines and the position facing the connection position on the loop, the plane parallel to the reflecting plate and parallel to the parallel two lines. A directivity control plate is provided that has a surface with sides and advances the phase of the reflected wave that is radiated from each dual-loop antenna element in a direction perpendicular to the loop surface and reflected by the reflector. is there.
[0011]
In the invention of claim 2, in addition to the configuration of claim 1, the directivity control plate is bent so that two opposing sides face each other and the two sides are parallel to the parallel two lines. Thus, it is preferable that the reflector is provided.
[0012]
According to a third aspect of the present invention, in addition to the configuration of the first or second aspect, the directivity control plate is preferably bent into a U-shaped cross -sectional shape , a U-shaped cross-sectional shape, or a trapezoidal cross -sectional shape .
[0013]
According to a fourth aspect of the present invention, in addition to the configuration according to any one of the first to third aspects, a balun may be formed by the support member and a feed line member that faces the support member and is connected to the feed line. .
[0014]
According to a fifth aspect of the present invention, in addition to the configuration according to any one of the first to fourth aspects, the power supply line is preferably a coaxial power supply line or a microstrip line arranged on a reflector. Furthermore, in the invention of claim 6, in addition to the structure of any one of claims 1 to 5, it is preferable that the shapes of the directivity control plates are the same.
[0015]
According to the present invention, the reflection is performed between the reflector and the loop of the double loop antenna element, and between the position where the loop is connected to the two parallel lines and the position facing the connection position on the loop. A plane parallel to the plate and having two sides parallel to the parallel two lines, and is radiated from each twin-loop antenna element in a direction perpendicular to the loop plane and reflected by the reflector. Since the directivity control plate for advancing the phase of the reflected wave from the reflecting plate is provided, a part of the reflecting plate is brought close to the double loop antenna element. For this reason, the phase of the reflected wave from the reflecting plate in the loop advances as compared with the case where there is no directivity control plate, and the directivity of the dual loop antenna changes. Accordingly, the apparent size when the reflector is viewed from the loop is relatively large as in the case where the loop and the reflector are close to each other, so that the same effect as when the aperture area is increased can be obtained. The horizontal plane beam width can be reduced.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
[0017]
FIG. 1 is an external perspective view showing an embodiment of a dual loop antenna of the present invention. In addition, the same code | symbol was used for the member similar to the prior art example shown in FIG. In this embodiment, a case of a 2L two-stage double loop antenna will be described.
[0018]
Reference numeral 10 denotes a reflective plate made of metal, and support members 11 to 14 are vertically provided on one surface side (front side in the drawing) of the reflective plate 10. Support members 11 and 12 on one side (left side in this case) are prisms made of metal (which may be a cylinder), and parallel two lines 6a and 6b are parallel to reflector 10 at one end (in this case, the upper end). It is provided to become. Two loops 2, 3 are connected to both ends of the parallel two lines 6 a, 6 b so that their loop surfaces are parallel to the reflector 10, thereby forming a double loop antenna element 8.
[0019]
The support members 13 and 14 on the other side (right side in this case) are also prisms made of metal (may be a cylinder) similarly to the support members 11 and 12, and the parallel two lines 7 a, 7 b is provided so as to be parallel to the reflector 10 and parallel to the two parallel lines 6 a and 6 b of the double loop antenna element 8. Two loops 4 and 5 are connected to both ends of the parallel two lines 7a and 7b so that their loop surfaces are parallel to the reflecting plate 10 to form a double loop antenna element 9 (both dual loop antenna elements 8). , 9 are supported by the support members 11 to 14 on the reflection plate 10 so as to be in a column).
[0020]
A feed line 19 of the balun 15 is provided in the vicinity of the support members 11 and 12 so as to face the support members 11 and 12, and a feed line 20 of the balun 16 is provided in the vicinity of the support members 13 and 14. It is provided to face. The balun 15 is composed of support members 11 and 12 and a feed line 19, and the balun 16 is composed of support members 13 and 14 and a feed line 20.
[0021]
Here, the baluns 15 and 16 are for balancing the potential on the loop side and the potential on the feeder line side, and the baluns 15 and 16 and the reflector 10 are electrically insulated.
[0022]
The power supply line 19 has a rising portion that is vertically raised from the one support member 11 side, and a power supply piece that is extended from the rising portion toward the other support member 12 side. The rising portion and the power feeding piece are formed in a straight line orthogonal to each other, and thus have an L shape. However, the present invention is not limited to this, and may be a J shape.
[0023]
Similarly to the balun 15, the balun 16 includes support members 13 and 14 and a feed line member 20. In the figure, a part of the parallel two lines 7b is broken for easy understanding.
[0024]
Directivity control plates 21, 22, 23, and 24 are provided between the reflector 10 and the loops 2 to 5 of both loop antenna elements 8 and 9, respectively.
[0025]
The directivity control plates 21 to 24 are provided on the reflection plate 10 so that the two opposite sides are bent so that the two opposite sides face each other and the two sides are parallel to the parallel two lines 6a, 6b, 7a, 7b. It is what was done. The directivity control plates 21 to 24 are formed in the same shape so that the shapes of the main beams radiated from the twin loop antenna elements 8 and 9 are equal. The height H of the directivity control plates 21 to 24 from the reflecting plate 10 is about 0.18 times the wavelength of the power fed to the twin loop antenna 25, and the width W is about 0.18 times the wavelength. The length L is preferably equal to the diameter of each loop 2-5. The directivity control plates 21 to 24 are bent into a U-shaped cross-sectional shape in the figure, but the present invention is not limited to this, and is bent into a V-shaped cross-sectional shape, a U-shaped cross-sectional shape, or a trapezoidal cross-sectional shape. It may be done.
[0026]
A coaxial feeder 17 is disposed on the other surface side (in this case, the back side) of the reflecting plate 10. The inner conductors (not shown) at both ends of the coaxial feeder 17 are connected to both baluns 15 and 16, and the outer conductors (not shown) at both ends are connected to the reflector 10. A feeding point 18 is disposed in the center of the coaxial feeding line 17.
[0027]
Metals such as copper, gold-plated copper, and silver-plated copper are used as materials for the reflector 10, the support members 11 to 14, the baluns 15 and 16, and the directivity control plates 21 to 24.
[0028]
Next, the operation of the double loop antenna shown in FIG. 1 will be described.
[0029]
When power is fed from a transmitter (not shown) to the feed point of the double loop antenna 25 shown in FIG. 1, power is distributed to both sides (left and right in the figure) of the coaxial feed line 17 and is unbalanced by the baluns 15 and 16, respectively. The line is converted to a balanced line, reaches the double-loop antenna elements 8 and 9 respectively, and radio waves are radiated from both the double-loop antenna elements 8 and 9 in both directions perpendicular to the loop surface. The radio wave radiated to one side (the lower side in the figure) is reflected by the reflector 10 and forward (the double loop antenna elements 8 and 9 of the reflector 10) together with the radio wave radiated to the other side (the upper side in this case). To the side). At this time, since the directivity control plates 21 to 24 are between the reflection plate 10 and the loops 2 to 5, a part of the reflection plate 10 is close to the loop antenna elements 8 and 9. For this reason, compared with the case where there is no directivity control board 21-24, the phase of the reflected wave from the reflecting plate 10 in each loop 2-5 advances, and directivity changes. In this case, there is an effect that the apparent size when the reflector 10 is viewed from the loops 2 to 5 is relatively increased as in the case where the loops 2 to 5 and the reflector 10 are close to each other. The horizontal beam width can be reduced as in the case where the opening area of the loop antenna 25 is increased. In addition, the voltage standing wave ratio (VSWR) of the dual loop antenna 25 differs depending on whether or not the directivity control plates 21 to 24 are present, but impedance conversion is performed inside the coaxial feeder 17. Can be adjusted.
[0030]
FIG. 2 is a diagram showing horizontal plane directivity when the twin-loop antenna shown in FIG. 1 is arranged so that the reflector is vertical. FIG. 3 is a diagram showing the four-loop antenna shown in FIG. It is a figure which shows horizontal surface directivity when arrange | positioning so that direction may differ for every 90 degree | times. FIG. 4 is a diagram showing horizontal plane directivity when the twin-loop antenna shown in FIG. 8 is arranged so that the reflector is vertical, and FIG. 5 is a diagram showing the four-loop antenna shown in FIG. It is a figure which shows horizontal surface directivity when arrange | positioning so that direction may differ for every 90 degree | times.
[0031]
2 to 5, the length of the half line extending from the origin indicates the directivity attenuation amount of the double loop antenna, and the angle of the half line indicates the angle of the double loop antenna in the horizontal plane.
[0032]
2-5, by using the directivity control plate for the double loop antenna, the horizontal plane beam width can be reduced without increasing the area of the reflector (opening area), and the orientation is changed every 90 degrees. It can be seen that good omnidirectionality can be obtained by arranging them differently.
[0033]
FIG. 6 is an external perspective view showing another embodiment of the dual loop antenna of the present invention.
[0034]
The difference between the double loop antenna shown in FIG. 6 and the double loop antenna shown in FIG. 1 is that a microstrip line is used instead of the coaxial feed line.
[0035]
A pair of support members 11 and 12 are vertically provided on one side (left side in the figure) on the reflector 10 shown in FIG. A twin loop antenna element 8 is supported at one end (in this case, the upper end) of the support members 11 and 12 so as to be parallel to the reflector 10. Similarly, a pair of support members 13 and 14 are provided on the other side (right side in this case) on the reflection plate 10 so as to be perpendicular to the reflection plate 10 and parallel to the support members 11 and 12. The double loop antenna element 9 is supported at one end (in this case, the upper end) of the support members 13 and 14 so as to be parallel to the reflector 10 and in tandem with the double loop antenna element 8.
[0036]
Directivity control plates 21 and 24 are provided between the outer loops 2 and 5 of the double-loop antenna elements 8 and 9 and the reflection plate 10, respectively.
[0037]
A balun 15 feed line 19 is provided in the vicinity of the support members 11 and 12 of the double loop antenna element 8 to form the balun 15, and a balun 16 feed line 20 is provided in the vicinity of the double loop antenna element 9. The balun 16 is configured. Both baluns 15 and 16 are connected by a microstrip line 30.
[0038]
The microstrip line 30 is fixed to the reflector 10 with a spacer 31 made of an insulator (for example, ceramic, glass, resin, etc.). In the center of the microstrip line 30, a feeding point 32 for feeding power from the back surface of the reflecting plate 10 is provided. On the reflecting plate 10, substantially ship-shaped shielding plates (copper plate, gold-plated copper plate, or silver-plated copper plate) 33a, 33b are provided so as to cover the bases of the microstrip line 30 and the baluns 15, 16 (shielding plate 33a). , 33b may be provided with a cover made of an insulator (not shown).
[0039]
Such a double-loop antenna 34 can provide the same effect as the double-loop antenna 25 shown in FIG.
[0040]
FIG. 7 is an external perspective view showing another embodiment of the twin-loop antenna of the present invention.
[0041]
The difference between the double loop antenna shown in FIG. 7 and the double loop antenna shown in FIG. 6 is that a directivity control plate is provided between all the loops and the reflection plate.
[0042]
The cross-sectional shapes of the directivity control plates 21a to 24a are U-shaped, but are substantially equal to or wider than the widths of the shielding plates 33a and 33b.
[0043]
In such a double loop antenna 40, the same effect as that of the double loop antenna 25 shown in FIG. 1 can be obtained.
[0044]
In the present embodiment, the description has been given of the case where the number of loops is four 2L two-stage dual loop antennas. However, the present invention is not limited to this, and even if the number of loops is two or six or more. I just need it.
[0045]
【The invention's effect】
In short, according to the present invention, it is possible to provide a double loop antenna capable of adjusting the horizontal plane beam width without increasing the area of the reflector.
[Brief description of the drawings]
FIG. 1 is an external perspective view showing an embodiment of a twin-loop antenna of the present invention.
FIG. 2 is a diagram showing horizontal plane directivity when the twin-loop antenna shown in FIG. 1 is arranged such that the reflector is vertical.
FIG. 3 is a diagram showing horizontal plane directivity when the four loop antennas shown in FIG. 1 are arranged so that the reflectors are vertical and the directions are different every 90 degrees.
4 is a diagram showing horizontal plane directivity when the twin-loop antenna shown in FIG. 8 is arranged so that the reflector is vertical. FIG.
FIG. 5 is a diagram showing horizontal plane directivity when the four-loop antenna shown in FIG. 8 is arranged so that the reflecting plate is vertical and the directions are different every 90 degrees.
FIG. 6 is an external perspective view showing another embodiment of the dual-loop antenna of the present invention.
FIG. 7 is an external perspective view showing another embodiment of the dual-loop antenna of the present invention.
FIG. 8 is an external perspective view showing a conventional example of a twin-loop antenna.
[Explanation of symbols]
2-5 Loops 6a, 6b, 7a, 7b Parallel two lines 8, 9 Double loop antenna element (2L double loop antenna element)
DESCRIPTION OF SYMBOLS 10 Reflecting plates 11-14 Support members 15, 16 Balun 17 Coaxial feed line 18 Feed point

Claims (6)

A plurality of twin-loop antenna elements in which two loops are connected by parallel two lines, a reflector, the reflector and the loop surface are parallel, and the twin-loop antenna elements are arranged in tandem on the reflector. A dual loop antenna comprising a support member for supporting a loop antenna element, wherein the loop is connected between the loops at both ends of at least one of the plurality of loops and the reflector , and the loop is connected to the parallel two lines. A surface parallel to the reflector and having two sides parallel to the parallel two lines between the position and the position facing the connection position on the loop, A dual loop antenna comprising a directivity control plate for advancing the phase of a reflected wave radiated in a direction perpendicular to a loop surface and reflected by the reflector.   2. The directivity control plate is provided on the reflection plate such that a rectangular metal plate is bent so that two opposite sides face each other, and the two sides are parallel to the parallel two lines. The double loop antenna described in 1. The dual-loop antenna according to claim 1 or 2, wherein the directivity control plate is bent into a U-shaped cross -sectional shape , a U-shaped cross-sectional shape, or a trapezoidal cross -sectional shape .   The twin loop antenna according to any one of claims 1 to 3, wherein a balun is formed by the support member and a feed line member facing the support member and connected to a feed line.   The double loop antenna according to any one of claims 1 to 4, wherein the feed line is a coaxial feed line or a microstrip line disposed on the reflector.   6. The dual loop antenna according to claim 1, wherein the directivity control plates have the same shape.

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