JP2012257031A - Antenna device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an antenna device capable of designing an antenna with a simple structure at low costs.SOLUTION: In an antenna device 1A, waveguide elements 21A, 22A, a twin loop radiator 10A and reflective elements 41A to 46A are attached to an antenna arm 51A in this order. For example, the antenna device 1A operates as a twin loop Yagi type antenna. All reflective elements 41A to 46A, the twin loop radiator 10A and waveguide elements 21A, 22A of the antenna device 1A are formed into a round bar shape. Therefore a wind receiving area is reduced in the antenna device 1A. These round bar-shaped elements are formed of Al pipes. The gain of the antenna device 1A can be enhanced by increasing the number of waveguide elements 21A, 22A.

Description

  The present invention relates to an antenna device, and more particularly to an antenna device using a dual loop antenna.

  The planar antenna with a reflector described in Patent Document 1 is provided with a planar reflector on the back surface of a planar radiating element made of a triangular double loop element. The side portions on both sides of the reflecting plate are bent toward the radiating element, and the distance between the tip edge of the side portion and the side edge of the radiating element is reduced. Thereby, even if the space | interval of a radiation element and a reflecting plate is narrowed, the electrical property of a planar antenna with a reflecting plate can be made favorable.

  The dual loop antenna described in Patent Document 2 changes the distance from the feeding point to one loop antenna and the distance to the other loop antenna, thereby changing the phase of the electromagnetic wave when power is fed to each loop antenna. There is a difference. The phase of the electromagnetic wave radiated from the loop antenna with the shorter distance from the feeding point advances in comparison with the phase of the electromagnetic wave radiated from the loop antenna with the longer distance from the feeding point.

  The double-loop antenna described in Patent Document 3 is a center-feed type loop antenna in which a pair of feed introduction portions are extended from an annular portion so that the arrangement direction and the wiring direction of the feed introduction portion are orthogonal to each other. It arrange | positions and it connects between the electric power feeding introduction parts of both loop antennas with a two-wire parallel electric power feeding line. In addition, the pair of power supply lines constituting the parallel power supply lines are not parallel but are inclined so that the line interval gradually changes.

  The double-loop antenna device described in Patent Document 4 is connected to the double loop, a reflector disposed behind, a support that fixes the double loop with a fixing bracket, a support that fixes the support, and the double loop. And a coaxial cable for transmitting signals, a back metal fitting for fixing the reflector plate and the column and fixing the mast to the mast, and a pressing metal fitting for holding the mast between the back metal fitting.

  The nullless antenna described in Patent Document 5 has a plurality of unit antennas. The unit antenna includes a plurality of radiating element units, a feeding point disposed between the radiating element units, and a feeding line that connects the feeding point and the radiating element unit. The feed line length from the feed point in the unit antenna to one radiating element portion is different from the feed line length to the other radiating element portion. Generation of nulls is suppressed by making the directivity of each unit antenna asymmetric.

JP 2009-261023 A JP 2004-015385 A JP 2000-307327 A JP-A-2005-110164 JP 2004-056319 A

  Conventional double loop antennas have been mainly used as transmitting antennas in the UHF (Ultra High Frequency) band. There is a receiving double loop antenna, but it has a low gain because it has only a double loop radiator and a reflector and no waveguide. Furthermore, the reflector is also a sheet metal that has been subjected to a bending process, and there is a problem that it is difficult to process.

  Therefore, an object of the present invention is to provide an antenna device capable of designing an antenna with a simple structure and a low cost.

  According to an aspect of the present invention, an antenna device includes a waveguide element, a double-loop radiator disposed behind the waveguide element, and a reflective element disposed behind the double-loop radiator. The waveguide element, the twin loop radiator, and the reflection element are all configured in a bar shape.

  According to another aspect of the present invention, there is provided an antenna device including a plurality of waveguide elements arranged in parallel vertically, a double loop radiator disposed behind the waveguide element, and a double loop radiator. A plurality of waveguide elements, a pair of waveguide elements that are closest to the double-loop radiator are configured in a plate shape, the rest are configured in a bar shape, and the plurality of reflection elements are in a rod shape It is configured.

  Preferably, the dual loop radiator includes two loop antenna units and two parallel transmission lines connecting the two loop antenna units, and the two loop antenna units adjust a voltage standing wave ratio. Each transmission line has a feeding point at the center point.

  Preferably, the antenna device further includes an antenna arm for arranging the waveguide element, the double loop radiator, and the reflection element at predetermined positions.

  Preferably, the antenna device is a terrestrial digital broadcast receiving antenna.

  According to the embodiment of the present invention, it is possible to realize an antenna device capable of designing a low-cost antenna with a simple structure.

It is the figure which showed the structure of 1 A of antenna apparatuses by Embodiment 1 of this invention. FIG. 2 is a diagram showing a specific structure of a twin loop radiator 10. It is a figure showing gain GN1 and voltage standing wave ratio VSWR1 of antenna device 1A. It is the figure which showed front-back ratio FB1 and half value width HW1 of 1 A of antenna apparatuses. It is the figure which showed the directivity in 470 MHz of 1 A of antenna apparatuses. It is the figure which showed the directivity in 590 MHz of 1 A of antenna apparatuses. It is the figure which showed the directivity in 710 MHz of 1 A of antenna apparatuses. It is the figure which showed the structure of the antenna device 1B by Embodiment 2 of this invention. It is the figure which showed gain GN2 and voltage standing wave ratio VSWR2 of the antenna device 1B. It is the figure which showed front-back ratio FB2 and half value width HW2 of the antenna device 1B. It is the figure which showed the directivity in 470MHz of the antenna apparatus 1B. It is the figure which showed the directivity in 590MHz of the antenna apparatus 1B. It is the figure which showed the directivity in 710 MHz of the antenna apparatus 1B.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals and description thereof will not be repeated.

[Embodiment 1]
FIG. 1 is a diagram showing a structure of an antenna device 1A according to Embodiment 1 of the present invention.

  Referring to FIG. 1, in antenna device 1A according to the first embodiment, waveguide elements 21A and 22A, a twin loop radiator 10A, and reflecting elements 41A to 46A are attached to an antenna arm 51A in this order. Yes. The antenna device 1A operates as, for example, a double-loop Yagi antenna. The dimension of the double loop radiator 10A is 410 mm long × 300 mm wide. The overall dimensions of the reflective elements 41A to 46A are 560 mm long × 340 mm wide. The depth dimension of the antenna device 1A varies depending on the number of waveguide elements 21A and 22A, but is generally within 350 mm to 500 mm.

  Conventionally, reflectors for such types of antennas are generally made by bending a sheet metal. On the other hand, the reflective elements 41A to 46A of the antenna device 1A are configured in a bar shape. Therefore, in the antenna device 1A, the wind receiving area is reduced. The double-loop radiator 10A and the waveguide elements 21A and 22A of the antenna device 1A are also configured in a bar shape. The reflecting elements 41A to 46A, the double loop radiator 10A, and the waveguide elements 21A and 22A are made of, for example, an aluminum pipe.

  Further, the antenna device 1A can be designed with a simpler structure than the conventional twin loop antenna, and the overall length (depth dimension) can be shortened with the same performance as the conventional Yagi type antenna. The antenna device 1A can increase the gain by increasing the number of waveguide elements 21A and 22A.

  FIG. 2 is a diagram showing a specific structure of the twin loop radiator 10. 2 corresponds not only to the double-loop radiator 10A of the first embodiment but also to the double-loop radiator 10B of the second embodiment.

  Referring to FIG. 2, the dual loop radiator 10 includes loop antenna units 11 and 14 and transmission lines 17 and 18. The loop antenna unit 11 includes VSWR adjustment stubs 12 and 13. The VSWR adjustment stubs 12 and 13 are provided to adjust the voltage standing wave ratio (VSWR) of the loop antenna unit 11. Similarly, the loop antenna section 14 includes VSWR adjustment stubs 15 and 16. The loop antenna portions 11 and 14 are 50 mm long × 300 mm wide and have a characteristic impedance of 300Ω.

  The transmission lines 17 and 18 have feeding points 17P and 18P, respectively, at the center point having a length of 300 mm. Thus, since the transmission lines 17 and 18 are fed at the center point, the characteristic impedance is 150Ω. The feeding points 17P and 18P are connected to a 75Ω coaxial cable via a balun.

  FIG. 3 is a diagram illustrating the gain GN1 and the voltage standing wave ratio VSWR1 of the antenna device 1A.

  As shown in FIG. 3, the gain GN1 has a high value of 6.5 dB to 8.0 dB in the 470 MHz to 710 MHz UHF band corresponding to the frequency band of digital terrestrial broadcasting. Further, the voltage standing wave ratio VSWR1 is suppressed to a low value of 2.7 or less in the same manner in the UHF band of 470 MHz to 710 MHz.

FIG. 4 is a diagram showing the front-rear ratio FB1 and the half-value width HW1 of the antenna device 1A.
Here, the front / rear ratio refers to the ratio [dB] of the maximum sensitivity between the maximum sensitivity direction of the antenna and the opposite direction (within a range of 180 ° ± 60 °). Further, the half-value width refers to an angle [degree] between which the azimuth is 3 dB lower than the operation gain in the principal axis direction of the antenna. As shown in FIG. 4, the front-rear ratio FB1 is a high value of 17.5 dB to 20.5 dB in the UHF band of 500 MHz to 710 MHz. The full width at half maximum HW1 is a relatively small value of 64 degrees to 68 degrees at 470 MHz to 710 MHz in the UHF band.

5 to 7 are diagrams showing the directivity of the antenna device 1A.
5 to 7 represent the directivities of the antenna device 1A at 470 MHz, 590 MHz, and 710 MHz, respectively. As illustrated in FIGS. 5 to 7, the antenna device 1 </ b> A has directivity in a single direction.

  As described above, the antenna device 1A according to the first embodiment has a configuration in which the waveguide elements 21A and 22A and the reflection elements 41A to 46A configured in a rod shape are added to the twin loop radiator 10A configured in a rod shape. It has become. With this configuration, it is possible to design a terrestrial digital broadcast receiving double loop antenna with a simple structure and low cost. In addition, the overall length can be shortened with performance comparable to that of a conventional Yagi antenna.

  The antenna device 1A holds all the elements with one antenna arm 51A. These elements are made of, for example, an aluminum pipe. With this configuration, as compared with the case where a sheet metal is used for the element or the antenna is surrounded by a housing, the size and weight can be reduced, the cost can be reduced, and the wind receiving area of the antenna can be reduced. Further, the gain of the antenna device 1A is increased by the addition of the waveguide elements 21A and 22A.

[Embodiment 2]
FIG. 8 shows a structure of antenna apparatus 1B according to the second embodiment of the present invention.

  Referring to FIG. 8, antenna device 1B according to the second embodiment includes an antenna arm 51B, waveguide elements 21B to 27B, 31B to 37B, a double loop radiator 10B, and reflection elements 41B to 48B. They are attached in order. The antenna device 1B operates as, for example, a double loop Yagi antenna. The overall dimensions of the reflective elements 41B to 48B are 560 mm long × 420 mm wide.

  The waveguide elements 21B to 27B and the waveguide elements 31B to 37B are arranged in parallel in the vertical direction. The waveguide elements 21B and 31B closest to the twin loop radiator 10B are configured in a plate shape. The waveguide elements 22B to 27B and 32B to 37B are configured in a rod shape. Moreover, the reflective elements 41B to 48B are configured in a bar shape. Reflective elements 41B-48B and waveguide elements 22B-27B, 32B-37B are made of aluminum pipes, for example. The waveguide elements 21B and 31B are made of sheet metal, for example.

  As described above, by increasing the number of waveguide elements and reflection elements and partially changing the structure, it is possible to improve the performance of the antenna device 1B as compared with the first embodiment as described below.

  FIG. 9 is a diagram showing the gain GN2 and the voltage standing wave ratio VSWR2 of the antenna device 1B.

  As shown in FIG. 9, the gain GN2 has a high value of 7.9 dB to 10.3 dB in the UHF band 470 MHz to 710 MHz corresponding to the frequency band of terrestrial digital broadcasting. As described above, in the antenna device 1B, the gain is larger than that in the first embodiment by increasing the number of waveguide elements and the like. As described above, the antenna device 1B has almost the same performance as the gain 7.5 dB to 12.0 dB of the conventional 14-element Yagi-type antenna, despite being downsized.

  Further, the voltage standing wave ratio VSWR2 is suppressed to a value of 2.5 or less, which is lower than that in the first embodiment, in the same UHF band of 470 MHz to 710 MHz.

FIG. 10 is a diagram showing the front / rear ratio FB2 and the half-value width HW2 of the antenna device 1B.
As shown in FIG. 10, the front-to-back ratio FB2 is a high value of 18.5 dB to 19.0 dB in the UHF band of 470 MHz to 710 MHz. The full width at half maximum HW2 is a further smaller value of 51 degrees to 61 degrees at 470 MHz to 710 MHz in the UHF band.

11 to 13 are diagrams showing the directivity of the antenna device 1B.
11 to 13 represent the directivities of antenna device 1B at 470 MHz, 590 MHz, and 710 MHz, respectively. As illustrated in FIGS. 11 to 13, the antenna device 1 </ b> B has directivity in a single direction as in the first embodiment.

  As described above, the antenna device 1B according to the second embodiment includes a waveguide element 21B to 27B, 31B in which a pair is configured in a plate shape and the remainder is configured in a rod shape in a double loop radiator 10B configured in a plate shape. To 37B and reflection elements 41B to 48B, all of which are configured in a bar shape, are added. With this configuration, the terrestrial digital broadcast receiving double loop antenna can be designed with a relatively simple structure and low cost.

  Further, by increasing the number of waveguide elements and reflection elements and partially changing the structure, it is possible to further improve performance such as gain, although the occupied volume is slightly increased, as compared with the first embodiment. Further, as in the first embodiment, the antenna device 1B holds all the elements with one antenna arm 51B. With this configuration, it is possible to reduce the size and weight, reduce the cost, and reduce the wind receiving area of the antenna as compared with the case where the antenna is surrounded by a casing.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is shown not by the above description of the embodiments but by the scope of claims for patent, and is intended to include meanings equivalent to the scope of claims for patent and all modifications within the scope.

  1A, 1B antenna device, 10, 10A, 10B double loop radiator, 11, 14 loop antenna section, 12, 13, 15, 16 adjustment stub, 17, 18 transmission line, 17P, 18P feed point, 21A, 22A, 21B-27B, 31B-37B Waveguide element, 41A-46A, 41B-48B Reflective element, 51A, 51B Antenna arm, FB1, FB2 front / rear ratio, GN1, GN2 gain, HW1, HW2 half width, VSWR1, VSWR2 standing wave ratio.

Claims (5)

A waveguide element;
A twin-loop radiator disposed behind the waveguide element;
A reflective element disposed behind the twin-loop radiator,
The antenna device, wherein the waveguide element, the double-loop radiator, and the reflection element are all configured in a bar shape. A plurality of waveguide elements arranged in parallel vertically,
A twin-loop radiator disposed behind the waveguide element;
A plurality of reflective elements disposed behind the twin-loop radiator,
In the plurality of waveguide elements, a pair closest to the double loop radiator is configured in a plate shape, and the rest is configured in a bar shape,
The plurality of reflecting elements are antenna devices configured in a bar shape. The dual loop radiator is:
Two loop antenna parts,
Including two parallel transmission lines connecting the two loop antenna portions,
The two loop antenna portions each have a stub region for adjusting a voltage standing wave ratio in the loop,
The antenna device according to claim 1, wherein the two transmission lines each have a feeding point at a center point.   The antenna device according to any one of claims 1 to 3, further comprising an antenna arm for disposing the waveguide element, the double loop radiator, and the reflection element at predetermined positions.   The antenna apparatus according to claim 1, wherein the antenna apparatus is a terrestrial digital broadcast receiving antenna.

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