JP2015080010A - Antenna and diversity communication system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an antenna which can be integrally manufactured and reduce deterioration in performance.SOLUTION: An antenna comprises: a plurality of leakage coaxial cables 1, each of which includes a linear central conductor for letting a signal propagate, an insulator covering the central conductor, and an external conductor covering the insulator and having a plurality of slots arranged at a fixed pitch along the axial direction of the central conductor, and which extend in parallel with each other; and a sheath 9 which covers the outer periphery of each of the plurality of leakage coaxial cables 1 and connects leakage coaxial cables 1 adjacent to each other. A frequency of the signal is within a range of 1.9 GHz to 3.7 GHz; distance between the centers of the leakage coaxial cables 1 adjacent to each other is within a range of being equal to or larger than λ/4 and equal to or smaller than 40 mm, where λ is a wavelength of the signal.

Description

  The present invention relates to an antenna using a leaky coaxial cable and a diversity communication system.

  A leaky coaxial cable (LCX) is one in which a plurality of slots are provided in the outer conductor of a normal coaxial cable. Through such a slot, an electromagnetic wave signal inside the cable can be emitted to the outside, or an electromagnetic wave signal outside the cable can be taken into the cable. That is, LCX is a cable type antenna and can be said to be a special long and narrow transmitting / receiving antenna.

  LCX is effective as an antenna in an environment with a long communication area. In particular, an electromagnetic wave insensitive zone is likely to occur in a winding tunnel or a place where many metal bodies exist. In such a place, if a general antenna is used, a large number of antennas must be installed. However, since each slot works as an antenna in LCX, a large number of antennas are arranged along LCX. Accordingly, it is difficult to generate an electromagnetic wave insensitive zone even in a long and narrow communication area by laying only one LCX. The laying work can be carried out very simply by simply extending the LCX, without the need to attach a general antenna individually for electrical wiring.

  In wireless communication, there are various electromagnetic wave paths from a transmission point to a reception point, and so-called multipaths exist. Therefore, a fading phenomenon occurs in the reception level due to the phase change of each reception wave and the polarization state change of each reception wave depending on the position of the reception point. There is a diversity method as a communication technique for improving such a fading phenomenon (see Non-Patent Document 1).

  In space diversity, a plurality of antennas with different positions are connected to a receiver, and an antenna with high reception strength is selected. In polarization diversity, a plurality of antennas having different polarization characteristics are respectively connected to a receiver, and an antenna with high reception intensity is selected.

  In Non-Patent Document 1, the function of diversity communication is described by reception diversity including one antenna on the transmission side and two antennas on the reception side. Conversely, transmission diversity having two antennas on the transmission side and one antenna on the reception side has the same function.

  LCX can also be used as an antenna for diversity communication. However, it is known that LCX is electrically affected by a close metal body or the like (see Non-Patent Document 2). Therefore, the setting of the distance between a plurality of LCXs is an important issue for the performance as an antenna for diversity communication.

  Patent Document 1 proposes a method of using LCX as a diversity communication antenna. In the proposed method, a diversity communication system is configured by arranging LCXs as sub-antennas in parallel with connection points of LCXs where reception levels drop. However, Patent Document 1 does not describe the LCX interval. When the LCXs are inadvertently arranged close to each other, there is a risk that the radiation characteristics of the LCXs are deteriorated and the antenna performance of the original LCX cannot be obtained.

  Further, in MIMO (Multiple-Input and Multiple-Output) using a plurality of antennas, a bundled leaky transmission line using LCX as an antenna has been proposed (see Patent Document 2). In the proposed bundled leaky transmission line, it is described that LCXs are integrated and separated from each other by λ / 2 or more, where λ is a signal wavelength. The frequency of a signal generally used in the current wireless LAN is 2.4 GHz, and the wavelength λ is 125 mm. Therefore, if the method of Patent Document 2 is adopted, the distance between LCXs must be 62.5 mm or more. Therefore, although it is possible to lay a plurality of LCXs individually, a problem arises when a plurality of LCXs are integrated in order to reduce construction costs and improve handling. Specifically, in the sheath extrusion process at the time of LCX production, it is difficult to extrude into a round shape so that the sheath diameter is 50 mm or more, and as suggested by Patent Document 2, it is 62.5 mm or more. It is very difficult to do.

Japanese Patent Publication No. 1-20813 Japanese Unexamined Patent Publication No. 2011-199760

"Antenna Engineering Handbook" first edition, IEICE, Ohmsha, published July 25, 2008 Kishimoto Toshihiko and Sasaki Shin “LCX Communication System” first edition, IEICE, Corona Publishing, August 20, 1982

  As described above, Patent Documents 1 and 2 propose the use of a plurality of LCXs as antennas in a diversity system aimed at stabilizing communication quality. However, in patent document 1, there is no description about the distance between LCX to install. In Patent Document 2, when applied to the current wireless LAN frequency band, the required distance between LCXs is difficult with a manufacturing technique in which LCXs that are normally used are integrated.

  In view of the above problems, an object of the present invention is to provide an antenna and a diversity communication system capable of integrally manufacturing a plurality of LCXs and capable of reducing performance degradation of the LCXs.

  According to the first aspect of the present invention, each includes a linear center conductor through which a signal propagates, an insulator covering the center conductor, a plurality of insulators covering the insulator, and at a constant pitch along the axial direction of the center conductor. A plurality of leaky coaxial cables each having an outer conductor in which slots are arranged and extending in parallel with each other; and a sheath that covers the outer periphery of each of the plurality of leaky coaxial cables and connects adjacent leaky coaxial cables. Provided is an antenna having a frequency in a range of 1.9 GHz to 3.7 GHz and an interval between adjacent leaky coaxial cables in a range of λ / 4 or more and 40 mm or less, where λ is a signal wavelength. .

  In the first aspect of the present invention, the longitudinal directions of the plurality of slots of the leaky coaxial cable may be arranged at an angle perpendicular to the axial direction, or arranged at an angle inclined with respect to the axial direction. Also good. The longitudinal directions of the plurality of slots of one leaky coaxial cable are arranged at an angle perpendicular to the axial direction, and the longitudinal directions of the plurality of slots of the other leaky coaxial cable are inclined with respect to the axial direction and are adjacent to each other. The slanted angles of the slots may be arranged at angles that are complementary to each other.

  According to the second aspect of the present invention, each of the linear center conductor through which the signal propagates, the insulator covering the center conductor, the insulator is covered, and a plurality of pitches are arranged at a constant pitch along the axial direction of the center conductor. A plurality of leaky coaxial cables each having an outer conductor in which slots are arranged and extending in parallel with each other; and a sheath that covers the outer periphery of each of the plurality of leaky coaxial cables and connects adjacent leaky coaxial cables. Provided is an antenna having a frequency in a range of 0.75 GHz to 3.7 GHz and a distance between adjacent leaky coaxial cable centers in a range of λ / 10 or more and 40 mm or less, where λ is a signal wavelength. .

  In the second aspect of the present invention, the longitudinal direction of the plurality of slots of the leaky coaxial cable may be inclined with respect to the axial direction, and the inclined angles of the adjacent slots may be arranged at angles that are complementary to each other.

  According to the 3rd aspect of this invention, the diversity communication system provided with the antenna as described in the 1st or 2nd aspect of this invention is provided.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to provide the antenna and diversity communication system which can manufacture several LCX integrally and can reduce the performance degradation of LCX.

It is the schematic which shows an example of the antenna which concerns on 1st embodiment of this invention. It is the schematic which shows an example of LCX used for the antenna which concerns on 1st embodiment of this invention. It is a side schematic diagram showing an example of a measurement system which measures the influence on the radiation of the distance between LCX. It is a back schematic diagram which shows an example of the measuring system which measures the influence with respect to radiation | emission of the distance between LCX. It is a figure which shows an example of the measurement result of the coupling loss of LCX shown in FIG. It is the schematic which shows an example of LCX used for the antenna which concerns on 2nd embodiment. It is a figure which shows an example of the measurement result of the coupling loss of LCX shown in FIG. It is a figure which shows the other example of the measurement result of the coupling loss of LCX shown in FIG. It is the schematic which shows an example of LCX used for the antenna which concerns on 3rd embodiment. It is a figure which shows an example of the measurement result of the coupling loss of LCX shown in FIG.

(First embodiment)
A first embodiment of the present invention will be described below with reference to the drawings. In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals. However, it should be noted that the drawings are schematic, and the relationship between the thickness and the planar dimensions, the ratio of the thickness of each layer, and the like are different from the actual ones. Therefore, specific thicknesses and dimensions should be determined in consideration of the following description. Moreover, it is a matter of course that portions having different dimensional relationships and ratios are included between the drawings.

  The first embodiment of the present invention shown below exemplifies an apparatus and method for embodying the technical idea of the present invention, and the technical idea of the present invention is the material of the component, The shape, structure, arrangement, etc. are not specified below. The technical idea of the present invention can be variously modified within the technical scope described in the claims.

  The antenna according to the first embodiment of the present invention can be used in a diversity communication system. As shown in FIG. 1, a plurality of leaky coaxial cables (hereinafter referred to as LCX) 1 and the outer periphery of each LCX 1 are provided. A sheath for covering and connecting adjacent LCXs is provided. Adjacent LCXs 1 are connected by a distance a between the centers.

  The LCX 1 includes a center conductor 3, an insulator 5, and an outer conductor 7, as shown in FIG. The center conductor 3 extends in the axial direction (z-axis direction) from the power supply side that supplies the high-frequency signal toward the terminal side. The insulator 5 is provided so as to cover the central conductor 3. The outer conductor 7 is provided so as to cover the insulator 5. The external conductor 7 is provided with a plurality of slots 10 at a constant pitch P along the axial direction of the LCX. The slot 10 has a rounded rectangular shape and is a vertical slot in which the longitudinal direction is arranged at an angle γ of 90 degrees with respect to the z-axis direction. The sheath 9 is provided so as to cover the outer periphery of the outer conductor 7 of the LCX 1.

  For example, the LCX 1 includes a center conductor 3 made of copper wire having a diameter of 2 mm, an insulator 5 made of foamed polyethylene having a relative dielectric constant εr of 1.5 and an outer diameter of 5 mm, and a copper foil outside having a thickness of 0.01 mm. A conductor 7 is used. The characteristic impedance of LCX1 is 50Ω, for example. The slot 10 has a length of 5 mm, a width of 2 mm, a pitch P of 80 mm, and an angle γ with respect to the z-axis direction is 90 degrees. The outer diameter of the sheath 9 is 7 mm.

  In the following description, as shown in FIGS. 3 and 4, two LCXs 1 and 1a are used as antennas. Further, the two LCXs 1 and 1a are not connected but arranged linearly in parallel with each other. LCX1a is the same as LCX1 shown in FIG.

  As shown in FIGS. 3 and 4, two LCXs 1, 1 a having a length of about 3 m are arranged on the radio wave absorber 30 with a distance a between the centers. A termination unit 12 of, for example, 50Ω, which is equal to the characteristic impedance of LCX1, is connected to the terminations of LCX1 and 1a to prevent reflection. In the coordinate system, a direction perpendicular to the surface of the radio wave absorber 30 is an x axis, a direction perpendicular to the axial direction of the LCX1, 1a on the radio wave absorber 30 surface is a y axis, and an axial direction of the LCX1, 1a is a z axis. The origin of the z-axis is set to a position of 1 m in a direction away from the terminal end from the feeding end of LCX1. That is, LCX1 is arrange | positioned in the position of z = 1m-4m. The origins of the x-axis and y-axis are the center position of LCX1, 1a and the center position between LCX1, 1a, respectively.

  A signal having an input power Pin and a frequency of 2.4 GHz is supplied from the transmitter 16 to the feeding end of the LCX 1 via the approach cable 18. The supplied signal is emitted from LCX1. The radiated wave radiated from the LCX 1 is received by a receiving antenna 20 such as a half-wavelength standard dipole antenna arranged at a height h from the x-axis origin in the x-axis direction. The receiving antenna 20 is connected to a receiver 22 that detects a received power Pout of a radiated wave via an approach cable 24 such as a general-purpose coaxial cable. The radiated wave from LCX1 is Ez polarization parallel to the axial direction of LCX1. Therefore, in order to receive the radiated wave from LCX1, the antenna element of the receiving antenna 20 is directed in the z-axis direction. The receiving antenna 20 is moved in a range of 0 m to 4 m in the z-axis direction at a position where the height h is about 1.5 m. The average value of the power received at each position on the z axis is defined as received power Pout. The coupling loss Lc representing the intensity of the radiated wave is calculated by the following equation. The smaller the coupling loss Lc, the stronger the radiation wave.

Lc = -10 log (Pout / Pin) (dB) (1)

In FIG. 5, the distance a between the centers of LCX1 and 1a is λ / 2 (62.5 mm), λ / 4 (31.3 mm), and λ / 10 (12.5 mm), where λ is the wavelength of the signal. For the case, the measurement result of coupling loss is shown. As shown in FIG. 5, when the distance a is as wide as λ / 2, the average value of the coupling loss is about 70 dB and the fluctuation is within 5 dB. When the distance a is reduced to λ / 4, the average value of the coupling loss is about 74 dB and the fluctuation is about 7 dB. As described above, when the distance a is λ / 4, the radiation is slightly weakened and the fluctuation is worsened, but it functions as an antenna. When the distance a is further narrowed to λ / 10, the average value of the coupling loss is about 85 dB and the fluctuation is about 20 dB. Thus, when the distance a is λ / 10, the radiation becomes extremely weak, the fluctuation is greatly deteriorated, and it no longer functions as an antenna.

  Therefore, in the first embodiment of the present invention, when a plurality of LCXs 1 are connected and integrated, the distance a between the centers of adjacent LCXs 1 is preferably λ / 4 or more. Further, in the extrusion process of the sheath of the LCX1, it is widely known in the technical field of cable manufacturing that the upper limit of the distance a is 40 mm due to restrictions on manufacturing apparatuses and manufacturing conditions. Thus, when the signal frequency is 2.4 GHz, the range of the desirable distance a is λ / 4, that is, 31 mm or more and 40 mm or less.

  From the experimental results shown in FIG. 5, it was found that the range of the desired distance a is not less than λ / 4 and not more than 40 mm. Here, considering the case of λ / 4 = 40 mm, λ = 160 mm, which is 1.87 GHz in terms of frequency. Patent Document 2 shows that the distance a is λ / 2. Considering the case of λ / 2 = 40 mm, λ = 80 mm, which is about 3.75 GHz in terms of frequency. Therefore, when the signal frequency is in the range of 1.9 GHz to 3.7 GHz, a range of λ / 4 or more and 40 mm or less can be applied as the distance a.

  Thus, by setting the distance a between the centers of the plurality of LCXs 1 to a range of λ / 4 or more and 40 mm or less, the plurality of LCXs can be manufactured integrally, and the performance deterioration of the LCX can be reduced. . As a result, the diversity communication system can be used as a high-performance antenna.

  In addition, although the above-mentioned experiment found the desirable distance a based on the measurement result of the radiated wave intensity from the antenna, it is also effective when the antenna receives a signal.

(Second embodiment)
As shown in FIG. 6, the LCX 1 used in the antenna according to the second embodiment of the present invention has a plurality of rounded rectangular slots arranged with the longitudinal direction inclined at the same angle γ with respect to the z-axis direction. 10 The length of the slot 10 is 12 mm, the width is 2 mm, and the angle γ is 30 degrees. From the LCX1 according to the second embodiment, radiated waves of Ez polarization parallel to the central axis (z axis) of the LCX1 and Ey polarization perpendicular to the z axis are radiated. The second embodiment is different from the first embodiment in that the slot 10 is an inclined slot having the same angle γ, and Ez polarization and Ey polarization are radiated. Other configurations are the same as those in the first embodiment, and thus redundant description is omitted.

  FIG. 7 and FIG. 8 show the results of measuring the coupling loss of the LCX 1 according to the second embodiment using the measurement system shown in FIG. 3 and FIG. The polarizations used for measurement are Ez polarization and Ey polarization, respectively.

  As shown in FIG. 7, for the Ez polarization, when the distance a is as wide as λ / 2, the average value of the coupling loss is about 65 dB, the fluctuation is within 5 dB, and the characteristics are the same as when the LCX 1 a is not arranged. is there. When the distance a is narrowed to λ / 4, the average value of the coupling loss is about 69 dB, and the radiation is slightly weakened, and the fluctuation is deteriorated to about 7 dB. However, it functions as an antenna. When the distance a is further narrowed to λ / 10, the average value of the coupling loss is about 85 dB, the radiation becomes extremely weak, and the fluctuation is deteriorated to about 20 dB. Therefore, when the distance a is λ / 10, it no longer functions as an antenna.

  For the Ey polarization, as shown in FIG. 8, when the distance a is as wide as λ / 2, the average value of the coupling loss is about 71 dB, the fluctuation is within 5 dB, and the characteristics are similar to those when the LCX 1 a is not arranged. is there. Even if the distance a is as narrow as λ / 4, the average value of the coupling loss is about 71 dB and the fluctuation is within 5 dB without any problem. Even if the distance a is further narrowed to λ / 10, the average value of the coupling loss is about 74 dB and the radiation is slightly weakened and the fluctuation is deteriorated to about 8 dB, but it functions as an antenna. However, when the distance a is 7 mm, that is, when the sheath 9 of LCX1, 1a is contacted, the average value of the coupling loss is 75 dB, the radiation is weakened, the fluctuation is deteriorated to 13 dB, and the performance as an antenna is greatly deteriorated.

  Therefore, in the second embodiment, when a plurality of LCXs 1 are connected and integrated, the distance a between the centers of adjacent LCXs 1 is preferably λ / 4 or more. Further, the distance a is desirably 40 mm or less because of the limitation in the extrusion process of the sheath of the LCX1. Thus, when the signal frequency is 2.4 GHz, the range of the desirable distance a is λ / 4, that is, 31 mm or more and 40 mm or less.

  From the experimental results shown in FIG. 7 and FIG. 8, it was found that the range of the desired distance a is not less than λ / 4 and not more than 40 mm. Here, considering the case of λ / 4 = 40 mm, λ = 160 mm, which is 1.87 GHz in terms of frequency. Patent Document 2 shows that the distance a is λ / 2. Considering the case of λ / 2 = 40 mm, λ = 80 mm, which is about 3.75 GHz in terms of frequency. Therefore, as in the first embodiment, when the signal frequency is in the range of 1.9 GHz to 3.7 GHz, a range of λ / 4 to 40 mm can be applied as the distance a. Thus, by setting the distance a between the plurality of LCXs 1 to a range of λ / 4 or more and 40 mm or less, the plurality of LCXs can be manufactured integrally, and the performance degradation of the LCX can be reduced. As a result, the diversity communication system can be used as a high-performance antenna.

  When using Ey polarization, the distance a may be in the range of λ / 10 to 40 mm. The signal frequency is also in the range of 0.75 GHz to 3.7 GHz.

(Third embodiment)
As shown in FIG. 9, the LCX 1 used for the antenna according to the third embodiment of the present invention is provided with a plurality of rounded rectangular slots 10a and 10b in a zigzag shape at a constant pitch P along the z axis. The slot 10a is disposed with its longitudinal direction inclined at an acute angle α with respect to the z-axis direction. The slot 10b adjacent to the slot 10a is provided with its longitudinal direction inclined at an obtuse angle β with respect to the z-axis direction. The angles α and β are complementary to each other. The slots 10a and 10b have a length of 12 mm and a width of 2 mm, and the angles α and β are 20 degrees and 160 degrees, respectively. From the LCX 1 according to the third embodiment, an Ey-polarized radiation wave perpendicular to the z-axis is radiated. In the third embodiment, the slots 10a and 10b are inclined slots having angles α and β, respectively, and are different from the first and second embodiments in that Ey polarized waves are radiated. Other configurations are the same as those in the first embodiment and the second embodiment, and thus redundant description is omitted.

  FIG. 10 shows the result of measuring the coupling loss of the LCX 1 according to the third embodiment using the measurement system shown in FIGS. 3 and 4. The polarization used for the measurement is Ey polarization. As shown in FIG. 10, when the distance a is as wide as λ / 2, the average value of the coupling loss is about 69 dB, the fluctuation is within 5 dB, and the characteristics are the same as when the LCX 1 a is not arranged. Even when the distance a is as narrow as λ / 4, the average value of the coupling loss is about 70 dB, and the fluctuation is within 5 dB without any problem. When the distance a is further narrowed to λ / 10, the average value of the coupling loss is about 73 dB, the radiation is slightly weakened, and the fluctuation is deteriorated to about 7 dB, but it functions as an antenna. However, when the distance a is 7 mm, that is, when the sheath 9 of LCX1, 1a is brought into contact, the average value of the coupling loss is 74 dB, the radiation is weakened, the fluctuation is deteriorated to 12 dB, and the performance as an antenna is deteriorated.

  Therefore, in the third embodiment, when a plurality of LCXs 1 are connected and integrated, the distance a between the centers of adjacent LCXs 1 is preferably λ / 10 or more. Further, the distance a is desirably 40 mm or less because of the limitation in the extrusion process of the sheath of the LCX1. Thus, when the signal frequency is 2.4 GHz, the range of the desirable distance a is λ / 10, that is, 12.5 mm or more and 40 mm or less.

  From the experimental results shown in FIG. 10, it was found that the range of the desirable distance a is not less than λ / 10 and not more than 40 mm. Here, considering the case of λ / 10 = 40 mm, λ = 400 mm, which is 0.75 GHz in terms of frequency. Patent Document 2 shows that the distance a is λ / 2. Considering the case of λ / 2 = 40 mm, λ = 80 mm, which is about 3.75 GHz in terms of frequency. Therefore, when the signal frequency is in the range of 0.75 GHz to 3.7 GHz, a range of λ / 10 or more and 40 mm or less can be applied as the distance a. As described above, by setting the distance a between the centers of the plurality of LCXs 1 to a range of λ / 10 or more and 40 mm or less, the plurality of LCXs can be manufactured integrally, and the performance degradation of the LCX can be reduced. As a result, the diversity communication system can be used as a high-performance antenna.

  In the above description, all of the plurality of LCXs 1 have the same shape slot. However, a plurality of LCXs having different slot shapes may be used. For example, the LCX of the vertical slot shown in FIG. 2 mainly using Ez polarization and the LCX having the zigzag slot shown in FIG. 9 mainly showing Ey polarization may be used. In this case, it can be applied not only to a spatial diversity communication system but also to a polarization diversity communication system.

(Other embodiments)
As described above, the first embodiment to the third embodiment have been described. However, it should not be understood that the description and drawings constituting a part of this disclosure limit the present invention. From this disclosure, various alternative embodiments, examples and operational techniques will be apparent to those skilled in the art. Accordingly, the technical scope of the present invention is defined only by the invention specifying matters according to the scope of claims reasonable from the above description.

1 ... Leaky coaxial cable (LCX)
DESCRIPTION OF SYMBOLS 3 ... Center conductor 5 ... Insulator 7 ... Outer conductor 9 ... Sheath 10, 10a, 10b ... Slot 12 ... Terminator

Claims (7)

Each includes a linear center conductor through which a signal propagates, an insulator covering the center conductor, an outer conductor covering the insulator, and having a plurality of slots arranged at a constant pitch along the axial direction of the center conductor. A plurality of leaky coaxial cables that extend parallel to each other;
A sheath for covering the outer periphery of each of the plurality of leaky coaxial cables and connecting adjacent leaky coaxial cables;
The frequency of the signal is in the range of 1.9 GHz to 3.7 GHz, and the distance between the centers of the adjacent leaky coaxial cables is in the range of λ / 4 or more and 40 mm or less, where λ is the wavelength of the signal. An antenna characterized by that.   2. The antenna according to claim 1, wherein each of the plurality of leaky coaxial cables is arranged such that longitudinal directions of the plurality of slots are perpendicular to the axial direction.   2. The antenna according to claim 1, wherein each of the plurality of leaky coaxial cables is arranged at an angle in which a longitudinal direction of the plurality of slots is inclined with respect to the axial direction. One of the plurality of leaky coaxial cables is arranged such that the longitudinal direction of the plurality of slots is perpendicular to the axial direction,
In another one of the plurality of leaky coaxial cables, the longitudinal direction of the plurality of slots is inclined with respect to the axial direction, and the inclined angles of adjacent slots are arranged at an angle that is complementary to each other. The antenna according to claim 1. Each includes a linear center conductor through which a signal propagates, an insulator covering the center conductor, an outer conductor covering the insulator, and having a plurality of slots arranged at a constant pitch along the axial direction of the center conductor. A plurality of leaky coaxial cables that extend parallel to each other;
A sheath for covering the outer periphery of each of the plurality of leaky coaxial cables and connecting adjacent leaky coaxial cables;
The frequency of the signal is in the range of 0.75 GHz to 3.7 GHz, and the distance between the centers of the adjacent leaky coaxial cables is in the range of λ / 10 or more and 40 mm or less, where λ is the wavelength of the signal. An antenna characterized by that.   Each of the plurality of leaky coaxial cables is characterized in that the longitudinal direction of the plurality of slots is inclined with respect to the axial direction, and the inclined angles of adjacent slots are arranged at angles that complement each other. The antenna according to claim 5.   A diversity communication system comprising the antenna according to claim 1.

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