JP2007104079A - Flat-type wideband antenna - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a flat-type wideband antenna which can be manufactured inexpensively, using a simple arrangement and is lightweight and withstands against wind velocity. <P>SOLUTION: Dipole elements 11a and 11b are constituted of double-square conductors and a central element 12 is provided in the center of a square loop element. The dipole elements 11a and 11b are arranged on a plane, while keeping an interval d of about λ/50, and a half wavelength dipole antenna is constituted by setting the length (overall length) L in the electric field direction at about λ/2, where λ is the wavelength at the resonance frequency of the half-wavelength dipole antenna. The dipole element 11a, 11b has an overall width W of about λ/3.75 or larger, and the width a of a peripheral conductor element and the width b of the conductor element of a central element 12 are set at about λ/60. The dipole elements 11a and 11b are provided with feeding points 13a and 13b at substantially in the center portion on the facing sides. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a planar broadband antenna capable of covering a plurality of wireless communication areas with a wireless communication requiring a broadband characteristic or a single antenna.

2. Description of the Related Art Conventionally, a two-wire dipole antenna is generally known as an antenna for receiving UHF band radio waves such as terrestrial digital broadcasting.
However, although the two-wire dipole antenna has a wide bandwidth and a high gain, it is configured using a conductor pipe, so the number of parts is increased, and it is troublesome to manufacture and difficult to downsize. There was a problem.
For this reason, recently, a wideband antenna for the UHF band, which has been reduced in size by using a plate-like dipole element formed in a substantially rectangular shape instead of the two-wire dipole antenna, has been considered (for example, Patent Document 1). reference.).
JP 2005-244926 A

  The conventional wideband antenna using the plate-shaped dipole element can be downsized with a simple configuration and has stable electrical characteristics such as gain and front / rear ratio over a wide band. There is a problem that the weight is increased and the wind pressure load on the element is large and the wind-resistant speed is weak as compared with the type dipole.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a planar wide-band antenna that can be manufactured at a low cost with a simple structure and is lightweight and strong against wind speed.

  According to a first aspect of the present invention, there is provided a planar broadband antenna, wherein a pair of dipole elements formed in the shape of a Japanese character by providing a central element at the center of a square loop-shaped element are arranged on a plane at a predetermined interval. A feeding point is provided at a substantially central portion on the opposite side of the element, and the length of the dipole element in the electric field direction is set to about ½ wavelength.

  A second invention is a planar broadband antenna according to the first invention, wherein the central element uses a plate-like element or a rod-like element, and the width or thickness is set so as to obtain a desired broadband characteristic. To do.

  According to a third aspect of the present invention, in the planar broadband antenna according to the first aspect, the central element is composed of a plurality of elements.

  According to the present invention, by constructing a planar broadband antenna with dipole elements formed in the shape of a Japanese character, the weight can be reduced compared with a broadband antenna using a plate-like dipole element, and wind pressure load can be reduced. An antenna that is reduced and strong against wind speed can be configured. In addition, the broadband characteristic can be arbitrarily variably set according to the width or thickness of the center element, and a desired broadband characteristic can be obtained with a simple configuration.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
(First embodiment)
FIG. 1 is a top view of a planar broadband antenna according to a first embodiment of the present invention.
In FIG. 1, 11a and 11b are a pair of dipole elements, which are composed of a Japanese-shaped conductor. That is, the dipole elements 11a and 11b are formed in the shape of a Japanese character by providing the central element 12 at the center of the square loop-shaped element. The dipole elements 11a and 11b are arranged on a plane, for example, with a distance d of about λ / 50, and the length (full length) L in the electric field direction is set to about λ / 2 to constitute a half-wave dipole antenna. ing. Λ is the wavelength of the resonance frequency of the half-wave dipole antenna.

  The dipole elements 11a and 11b have an overall width W of about λ / 3.75 or more, a surrounding (square loop) conductor element width a, and a center element 12 conductor element width b of about λ / 60. . The dipole elements 11a and 11b are provided with feeding points 13a and 13b at substantially central portions on the sides close to each other. The feed points 13a and 13b are provided with, for example, through holes, and a central conductor and an outer conductor of a feed coaxial cable (not shown) are connected to the through hole portions, respectively.

  FIG. 2 shows the planar broadband antenna according to the first embodiment, in which the resonance frequency f is 1 GHz, the length L in the electric field direction of the dipole elements 11a and 11b is λ / 2 (150 mm), and the width W is λ / 3 ( VSWR (voltage standing wave ratio) characteristics when the distance d is set to λ / 50 (6 mm), the surrounding conductor element width a and the center element 12 conductor element width b are set to λ / 60 (5 mm). It is shown. At this time, the ratio band of VSWR ≦ 2 was 74%, and sufficient broadband characteristics were obtained. The planar broadband antenna has an overall width W of about λ / 3.75 (80 mm) or more when the conductor element width a of the dipole elements 11a and 11b and the conductor element width b of the center element 12 are about λ / 60. By setting to, broadband characteristics can be obtained.

FIG. 3 shows the VSWR characteristics when the width W of the dipole elements 11a and 11b is about λ / 5 (60 mm) and the other dimensions are set to be the same as those in FIG. In this case, the ratio band of VSWR ≦ 2 is about 23% in the low frequency range of the resonance frequency f _L = 0.8 GHz and about 22% in the high frequency range of the resonance frequency f _H = 1.76 GHz, which is 0.8 GHz. It becomes the characteristic of the dual frequency antenna of 1.76 GHz.

FIG. 4 shows, for comparison, the VSWR characteristics when the center element 12 of the dipole elements 11a and 11b is not provided in the planar broadband antenna shown in the first embodiment. Other conditions are shown in FIG. Is the same as Without the central element 12, the characteristic of VSWR ≦ 2 is a very narrow band with a relative band of about 1% near 0.6 GHz.
As is clear from the VSWR characteristics shown in FIGS. 3 and 4, it is possible to increase the bandwidth by providing the center element 12 in the dipole elements 11 a and 11 b.

FIG. 5 is a diagram showing the relationship between the low-band resonance frequency f _L and the high-band resonance frequency f _{H in} the planar broadband antenna. The horizontal axis represents the width W of the dipole elements 11a and 11b, and the vertical axis represents the frequency high frequency. The resonance frequency f _{H of the} region is shown. The high-band resonance frequency f _H of the vertical axis is shown as n times the low-band resonance frequency f _L. Since the low frequency resonance frequency f _L does not change much even if the width W of the dipole elements 11a and 11b is changed, the correspondence between the width W of the dipole elements 11a and 11b and the high frequency resonance frequency f _H is as shown in FIG. Can be represented. Therefore, it is possible to obtain the high-band resonance frequency f _H when set to a certain value dipole elements 11a, 11b a width W from FIG.

For example, the resonance frequency f of the antenna is 1 GHz,
λ = 300mm (1GHz)
f _L = 1 GHz × 0.8 = 0.8 GHz
When the width W of the dipole elements 11a and 11b is W = λ / 4 (75 mm)
5, “f _L × 2.07 times” is obtained as the high-band resonance frequency f _H from FIG. Therefore, the high frequency resonance frequency f _H is
F _H = f _L × 2.07
= 0.8GHz × 2.07
= 1.66 GHz
It becomes.

FIG. 6A shows the planar broadband antenna according to the first embodiment under the same conditions as in FIG. 3, that is, at a frequency of 0.8 GHz when the width W of the dipole elements 11a and 11b is set to λ / 5. It is a figure which shows the radiation directivity characteristic of a XZ plane.
FIG. 6B is a diagram showing the radiation directivity characteristics on the YZ plane at a frequency of 0.8 GHz when the width W of the dipole elements 11a and 11b is set to λ / 5.
FIG. 7A is a diagram showing the radiation directivity characteristics on the XZ plane at a frequency of 1.8 GHz when the width W of the dipole elements 11a and 11b is set to λ / 5.
FIG. 7B is a diagram showing the radiation directivity characteristics on the YZ plane at a frequency of 1.8 GHz when the width W of the dipole elements 11a and 11b is set to λ / 5.
The directivity of the XZ plane shown in FIGS. 6 (a) and 7 (a) is an 8-shaped directivity characteristic, and the directivity of the YZ plane shown in FIGS. 6 (b) and 7 (b). Is omnidirectional.

  According to the above embodiment, since the wideband antenna is constituted by the dipole elements 11a and 11b formed in the shape of a Japanese character, the weight can be reduced as compared with the wideband antenna using the plate-like dipole element, and It is possible to reduce the wind pressure load and configure an antenna that is resistant to wind speed. Moreover, it is possible to obtain a wide band characteristic with a simple configuration.

In the above embodiment, the antenna elements, that is, the dipole elements 11a and 11b and the central element 12 are configured by plate elements, but may be configured by rod elements.
The antenna element may be formed on a substrate made of a dielectric.

(Second Embodiment)
Next, a planar broadband antenna according to a second embodiment of the present invention will be described.
FIG. 8 is a top view of a planar broadband antenna according to the second embodiment of the present invention. In the planar broadband antenna according to this embodiment, the conductor element width b of the center element 12 of the dipole elements 11a and 11b is set wide, for example, about λ / 20. The rest of the configuration is substantially the same as that of the planar broadband antenna according to the first embodiment.

  FIG. 9 shows a planar broadband antenna according to the second embodiment in which the resonance frequency f is 1 GHz, the length L in the electric field direction of the dipole elements 11a and 11b is λ / 2 (150 mm), and the width W is λ / 4 (70 mm). ), VSWR characteristics when the distance d is set to λ / 50 (6 mm), the surrounding conductor element width a is set to λ / 60 (5 mm), and the conductor element width b of the center element 12 is set to λ / 20 (15 mm). It is a thing. When the conductor element width b of the center element 12 is set to λ / 60 (5 mm), the VSWR characteristic near 1.1 GHz is 2 or more as shown in FIG. Is set to about λ / 20 (15 mm), for example, so that the VSWR near 1.1 GHz can be improved to 2 or less in the band while maintaining the wideband characteristics.

  According to the second embodiment, the wide band characteristics can be improved by forming the conductor element width b of the center element 12 of the dipole elements 11a and 11b wide. Therefore, by adjusting the conductor element width b of the center element 12, it becomes possible to variably set the wideband characteristics.

(Third embodiment)
Next, a planar broadband antenna according to a third embodiment of the present invention is described.
FIG. 10 is a top view of a planar broadband antenna according to a third embodiment of the present invention. In the first and second embodiments, a plate-like element is used as the central element 12 of the dipole elements 11a and 11b. However, in the third embodiment, a plurality of, for example, two conductor wires 12a and 12b are used as the central element 12. Used and arranged at a predetermined interval. In this example, the line width e of the conductor wires 12a and 12b is set to about λ / 300 (1 mm), and the interval f is set to about λ / 20 (15 mm). The rest of the configuration is the same as that of the planar broadband antenna according to the second embodiment.

  FIG. 11 shows a planar broadband antenna according to the third embodiment in which the resonance frequency f is 1 GHz, the length L in the electric field direction of the dipole elements 11a and 11b is λ / 2 (150 mm), and the width W is λ / 4 ( 70 mm), the distance d is λ / 50 (6 mm), the surrounding conductor element width a is λ / 60 (5 mm), the line width e of the conductor wires 12a and 12b constituting the center element 12 is λ / 300 (1 mm), The VSWR characteristic when the interval f is set to λ / 20 (15 mm) is shown.

12A is a diagram showing the radiation directivity characteristics on the X-Z plane at a frequency of 0.8 GHz of the planar broadband antenna set under the same conditions as in FIG. 11, and FIG. It is a figure which shows the radiation directivity characteristic of the YZ surface in 8 GHz.
FIG. 13A is a diagram showing the radiation directivity characteristic of the XZ plane at the frequency 1.25 GHz of the broadband antenna, and FIG. 13B is the radiation directivity characteristic of the YZ plane at the frequency 1.25 GHz of the broadband antenna. FIG.
FIG. 14A is a diagram showing the radiation directivity characteristic of the XZ plane at a frequency of 1.7 GHz of the broadband antenna, and FIG. 14B is the radiation directivity characteristic of the YZ plane at a frequency of 1.7 GHz of the broadband antenna. FIG.
According to the third embodiment, the central element 12 of the dipole elements 11a and 11b is constituted by the two conductor wires 12a and 12b, so that the weight can be reduced and the wind receiving load can be reduced, and the dipole elements 11a and 11b can be reduced. A VSWR characteristic equivalent to that of the second embodiment using a plate-like element as the central element 12 can be obtained.

  In the third embodiment, the case where the central element 12 of the dipole elements 11a and 11b is configured by the two conductor lines 12a and 12b has been described. However, the center element 12 may be configured by using three or more conductor lines.

(Fourth embodiment)
Next, a planar broadband antenna according to a fourth embodiment of the present invention is described.
FIG. 15 is a top view of a planar broadband antenna according to a fourth embodiment of the present invention. In the planar broadband antenna according to this embodiment, the center element 12 of the dipole elements 11a and 11b is constituted by two conductor lines 12a and 12b, and the conductor lines are also provided around the dipole elements 11a and 11b (rectangular loop). In other words, all the elements are composed of thin conductor wires. The conductor lines 12a and 12b of the dipole elements 11a and 11b and the central element 12 have line widths a and e set to about λ / 300 (1 mm), and a distance f between the conductor lines 12a and 12b is set to about λ / 20 (15 mm). ) Is set.

  The dipole elements 11a and 11b have a total length L of about λ / 2 (300 mm), a width L of about λ / 3 (95 mm), and a distance d of about λ / 150 (2 mm).

  FIG. 16 shows the VSWR characteristics of the planar broadband antenna according to the fourth embodiment. In this case, the ratio band of VSWR ≦ 2 is about 70%, and a sufficient broadband characteristic was obtained.

  Since the flat broadband antenna according to the fourth embodiment has all the elements formed of thin conductor wires, it can be formed on a transparent dielectric film, for example, attached to a window glass of an automobile. Can be used. Further, the antenna element can be made inconspicuous by thinning the antenna element as described above, and the aesthetic appearance can be maintained even when the antenna element is attached to an automobile window glass.

  Note that the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying constituent elements without departing from the scope of the invention in the implementation stage.

1 is a top view of a planar broadband antenna according to a first embodiment of the present invention. In the same embodiment, it is the VSWR characteristic figure when width W of the dipole element is set to approximately λ / 3. In the same embodiment, it is the VSWR characteristic figure when width W of the dipole element is set to approximately λ / 5. In the same embodiment, it is a VSWR characteristic view when there is no central element of the dipole element. In this embodiment, showing the relationship between the width W and the high-band resonance frequency f _H of the dipole elements. The antenna directivity characteristic in the same embodiment is shown, (a) is a directivity characteristic diagram of the XZ plane at a frequency of 0.8 GHz when the width W of the dipole element is set to about λ / 5, (b) is the Y- It is a directional characteristic diagram of the Z plane. The antenna directivity characteristic in the same embodiment is shown, (a) is a directivity characteristic diagram of the XZ plane at a frequency of 1.8 GHz when the width W of the dipole element is set to about λ / 5, (b) is the Y- It is a directional characteristic diagram of the Z plane. It is a top view of the planar wideband antenna concerning a 2nd embodiment of the present invention. In the same embodiment, it is the VSWR characteristic figure when width W of the dipole element is set to approximately λ / 4. It is a top view of the planar broadband antenna which concerns on 3rd Embodiment of this invention. In the same embodiment, it is the VSWR characteristic figure when width W of the dipole element is set to approximately λ / 4. The antenna directivity characteristic in the same embodiment is shown, (a) is a directivity characteristic diagram of the XZ plane at a frequency of 0.8 GHz when the width W of the dipole element is set to about λ / 4, (b) is the Y- It is a directional characteristic diagram of the Z plane. The antenna directivity characteristic in the same embodiment is shown, (a) is a directivity characteristic diagram of the XZ plane at a frequency of 1.25 GHz when the width W of the dipole element is set to about λ / 4, (b) is the Y- It is a directional characteristic diagram of the Z plane. The antenna directivity characteristic in the same embodiment is shown, (a) is a directivity characteristic diagram of the XZ plane at a frequency of 1.7 GHz when the width W of the dipole element is set to about λ / 4, (b) is the Y- It is a directional characteristic diagram of the Z plane. It is a top view of the planar broadband antenna which concerns on 4th Embodiment of this invention. In the same embodiment, it is the VSWR characteristic figure when width W of the dipole element is set to approximately λ / 4.

Explanation of symbols

  11a, 11b ... dipole element, 12 ... center element, 12a, 12b ... conductor wire, 13a, 13b ... feeding point.

Claims (3)

  A pair of dipole elements formed in the shape of a Japanese character by providing a central element in the central part of a square loop-shaped element are arranged on a plane at a predetermined interval, and power is supplied to the substantially central part on the opposite side of the dipole element. A flat broadband antenna characterized in that a point is provided and the length of the dipole element in the electric field direction is set to about ½ wavelength.   The planar broadband antenna according to claim 1, wherein the central element uses a plate-shaped element or a rod-shaped element, and has a width or thickness set so as to have a desired broadband characteristic.   The planar broadband antenna according to claim 1, wherein the central element is constituted by a plurality of elements.

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