JPH11284425A - Bidirectional switch antenna device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To miniaturize a device, to reduce cost and to provide a radiation characteristic which can be used for transmission/reception with respect to all the directions of a horizontal face, without complicating constitution in a bidirectional switch antenna device. SOLUTION: A bidirectional switch antenna device, constituted by combining a plurality of element antennas whose directivity on a horizontal face are almost non-directional is constituted of at least two element antennas 12, 13, 15 and 16 which are arranged in a horizontal direction at the intervals of the almost half wavelength of the free space wavelength of the used frequency, a 90-degree phase shifter 14 connected to one of two element antennas 12, 13, 15 and 16 and a 90-degree hybrid circuit 17, in which two output terminals are connected to the inputs of the two element antennas 12, 13, 15 and 16.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bidirectional switching antenna device formed by combining a plurality of element antennas each having a substantially non-directional directivity in a horizontal plane.

[0002]

2. Description of the Related Art As a conventional example of this type of antenna device, there is known a printed antenna disclosed in Japanese Patent Application Laid-Open No. 7-183724. That is, a bidirectional antenna device is configured by combining two single printed dipole antennas, each of which has almost directivity in the horizontal plane.

In this printed antenna, a relatively uniform bidirectional radiation pattern is formed.

[0004]

For example, an antenna used by a radio base station is required to have uniform radiation characteristics over the entire circumference of a horizontal plane.

[0005] In order to achieve uniform radiation characteristics over the entire circumference, even when a conventional bidirectional antenna device is used, two sets of antennas whose arrangement directions are shifted from each other by 90 degrees on a horizontal plane are combined. Must be used. Therefore, there is a disadvantage that the number of antennas increases.
Further, since two sets of antennas are required, the shape of the entire antenna is increased. Also, the manufacturing cost is increased.

According to the present invention, in a bidirectional switching antenna device, the size and cost of the device can be reduced, and radiation characteristics usable for transmission and reception in all directions in a horizontal plane can be obtained without complicating the configuration. Its main purpose is to:

[0007]

According to a first aspect of the present invention, there is provided a bidirectional switching antenna device comprising a combination of a plurality of element antennas each having a substantially horizontal directivity. At least two element antennas arranged side by side in a horizontal direction at an interval of about a half wavelength of a free space wavelength, a 90-degree phase shifter connected to one of the two element antennas, and two output terminals. A 90-degree hybrid circuit connected to inputs of two element antennas is provided.

For example, in the case of transmission, the power input to the 90-degree hybrid circuit is divided into two equal parts, and appears at two output terminals of the 90-degree hybrid circuit. Further, a phase difference of 90 degrees occurs between the signals of the two output terminals.

When power is supplied from one input terminal of a 90-degree hybrid circuit, a signal supplied to one element antenna has a 90-degree phase difference generated by a 90-degree phase shifter and the other element has a phase difference of 90 degrees. Since a 90-degree hybrid circuit generates a 90-degree phase difference in the signal supplied to the antenna, the two element antennas are supplied with the same phase.

On the other hand, when power is supplied from the other input terminal of the 90-degree hybrid circuit, a signal supplied to one element antenna has a 90-degree phase difference in the 90-degree hybrid circuit and further has a 90-degree phase difference. Since the phase shifter generates a phase difference of 90 degrees, a phase difference of 180 degrees is generated. Since the phase difference of the signal supplied to the other element antenna is 0 degree, the two element antennas are fed with phases opposite to each other.

The direction of the radiation pattern formed by the two element antennas is shifted by about 90 degrees between the case where the two element antennas are fed with the same phase and the case where the two element antennas are fed with the opposite phase. Therefore, a necessary radiation pattern can be obtained by switching the input terminal of the 90-degree hybrid circuit as needed. According to a second aspect of the present invention, in the bidirectional switching antenna device according to the first aspect, the element antenna is configured by a foil-shaped dipole antenna formed on a substrate made of a dielectric, and the 90-degree phase shifter and the hybrid circuit are provided. Is made of a foil-shaped conductor formed on the substrate.

Since the bidirectional switching antenna device can be constituted only by the substrate and the foil-like conductor, the thickness can be reduced.
In particular, since there is no need to arrange or combine a plurality of substrates, an extremely thin bidirectional switching antenna device can be configured. According to a third aspect of the present invention, in the bidirectional switching antenna device according to the second aspect, the dipole antenna is formed by a first foil-shaped conductor formed along a front surface of the substrate and a second foil formed along a back surface. And a foil-shaped conductor.

By using the conductor patterns formed on both surfaces of the substrate as a pair, the impedance characteristics of each part are stabilized. That is, since only the substrate exists between the two conductor patterns on the front and back sides, the impedance does not easily change.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) FIGS. 1 to 3 show the configuration and operation of a bidirectional switching antenna device of this embodiment.
Shown in This embodiment corresponds to claim 1.

FIG. 1 is a front view of a bidirectional switching antenna device. FIG. 2 is a rear view of the bidirectional switching antenna device of FIG. FIG. 3 is a graph showing radiation characteristics of a horizontal plane of the bidirectional switching antenna device of FIG. In this embodiment, the two element antennas of claim 1 are a front printed dipole element 12, 15 and a back printed dipole element 1.
The 90-degree phase shifter and the 90-degree hybrid circuit of claim 1 correspond to the 90-degree phase shifter 14 and the hybrid circuit 17, respectively.

The antenna substrate 11 shown in FIG. 1 and FIG.
This is a rectangular substrate made of a dielectric and having a uniform thickness. Also, a pattern including the surface-printed dipole elements 12, 15 is formed on the front side surface as shown in FIG. Have been.

On the back surface of the antenna substrate 11,
As shown in FIG.
6 are formed. The front printed dipole elements 12, 15 and the back printed dipole elements 13, 16 are separated from each other. In this example, the front printed dipole element 12 and the back printed dipole element 13 constitute one dipole antenna, and the front printed dipole element 15 and the back printed dipole element 16 constitute another dipole antenna.

The distance between the front printed dipole element 12 and the front printed dipole element 15 and the back printed dipole element 13 and the back printed dipole element 16
Is set so as to substantially coincide with 0.5 wavelength (0.5λo) of the free space wavelength of the frequency used by the bidirectional switching antenna device. As shown in FIG. 1, a 90-degree phase shifter 14 and a hybrid circuit 17 are provided on the front side of the antenna substrate 11. Hybrid circuit 17 is 3d
B hybrid circuit, having two input terminals A1, A2
And two output terminals B1 and B2.

The output terminal B1 of the hybrid circuit 17 is
It is connected to the front printed dipole element 12 via a 90-degree phase shifter 14. The operation of the bidirectional switching antenna device shown in FIGS. 1 and 2 will be described. When the transmission power is supplied between one input terminal A1 of the hybrid circuit 17 and the terminal E1 on the back surface, the phase difference with respect to the phase of the input terminal A1 is 0 degree at the output terminal B1. Since the light passes through the 90-degree phase shifter 14, a 90-degree phase difference is generated at the position of the feeding point of the front printed dipole element 12.

On the other hand, the output terminal B of the hybrid circuit 17
In 2, a phase difference of 90 degrees occurs. Since a signal having the same phase as that of the output terminal B2 of the hybrid circuit 17 appears at the feeding point of the front printed dipole element 15, a phase difference of 90 degrees occurs also at the feeding point of the front printed dipole element 15. Therefore, when power is supplied from the input terminal A1 of the hybrid circuit 17, the two surface-printed dipole elements 12 and 15 are supplied with the same phase.

When transmission power is supplied between the other input terminal A2 of the hybrid circuit 17 and the terminal E2 on the back surface, the phase difference with respect to the phase of the input terminal A2 is 90 degrees at the output terminal B1. Since the light passes through the 90-degree phase shifter 14, a 180-degree phase difference is generated at the position of the feeding point of the front surface printed dipole element 12.

On the other hand, the output terminal B of the hybrid circuit 17
At 2, the phase difference is 0 degrees. The output terminal B of the hybrid circuit 17 is connected to the feeding point of the front printed dipole element 15.
Since a signal having the same phase as 2 appears, the phase difference between the feeding points of the front printed dipole element 15 also becomes 0 degree. Therefore, when power is supplied from the input terminal A2 of the hybrid circuit 17, the two surface printed dipole elements 12 and 15 are supplied with phases opposite to each other, that is, with a phase difference of 180 degrees.

That is, two input terminals A used for power supply
By switching between A1 and A2, it is possible to select whether the phase of the power supply signal relative to the two surface printed dipole elements 12 and 15 is the same or opposite. The radiation pattern formed by this bidirectional switching antenna device is as shown in FIG. FIG. 3 shows a radiation pattern on a horizontal plane when the bidirectional switching antenna apparatus shown in FIG. 1 is set up perpendicular to the plane of FIG. That is, the direction perpendicular to the paper surface of FIG. 3 matches the Y-axis direction of FIG.

As shown in FIG. 3, the radiation pattern of this bidirectional switching antenna device changes greatly according to the difference between the in-phase / out-phase of the feed signal. In particular, the directions of the radiation patterns differ from each other by approximately 90 degrees. That is, by combining the hybrid circuit 17 and the 90-degree phase shifter 14, two types of bidirectional radiation patterns can be formed. Input terminals A1, A used for power supply as required
By performing the switching control of No. 2, transmission and reception can be performed in all horizontal directions.

Further, since a radiation pattern corresponding to two types of antenna devices can be obtained with one type of bidirectional switching antenna device, there is an advantage that cost reduction can be realized.
In this example, a dipole antenna is used as an example of an antenna that realizes omnidirectionality in a horizontal plane, but a whip antenna, a helical antenna, a collinear antenna, or the like may be used instead.

(Second Embodiment) FIGS. 4 and 5 show the configuration of a bidirectional switching antenna device of this embodiment. This form corresponds to all claims. FIG. 4 is a front view of the bidirectional switching antenna device of this embodiment. FIG. 5 is a rear view of the bidirectional switching antenna device of FIG.

In this embodiment, the two element antennas of claim 1 correspond to the front printed dipole elements 32 and 35 and the back printed dipole elements 33 and 36, respectively, and the 90-degree phase shifter and the 90-degree hybrid circuit of claim 1 Correspond to the microstrip 90-degree phase shifter 34 and the microstrip hybrid circuit 37, respectively. This embodiment is a modification of the first embodiment, in which the entirety of the bidirectional switching antenna device is constituted only by a planar circuit. Although there is no significant difference in function as compared with the first embodiment, in this embodiment, a further miniaturized bidirectional switching antenna device is realized.

The antenna substrate 31 shown in FIG. 4 and FIG.
This is a rectangular substrate made of a dielectric and having a uniform thickness. Also, a pattern including the surface printed dipole elements 32 and 35 is formed on the front side surface as shown in FIG. 1 by preliminarily processing the conductor of the metal foil adhered to both sides of the antenna substrate 31 by etching or the like. Have been.

On the back surface of the antenna substrate 31,
As shown in FIG. 5, the back side printed dipole elements 33, 3
6 are formed. The front printed dipole elements 32 and 35 and the back printed dipole elements 33 and 36 are separated from each other.

In this example, the front printed dipole element 32 and the back printed dipole element 33 constitute one dipole antenna, and the front printed dipole element 35 and the back printed dipole element 36 constitute another dipole antenna. The distance between the front printed dipole element 32 and the front printed dipole element 35 and the distance between the back printed dipole element 33 and the back printed dipole element 36 are 0.5 of the free space wavelength of the frequency used by the bidirectional switching antenna device. It is determined so as to substantially coincide with the wavelength (0.5λo).

As shown in FIG. 4, a microstrip 90-degree phase shifter 34 and a microstrip hybrid circuit 37 are provided on the front side of the antenna substrate 11. The microstrip hybrid circuit 37 is a 3 dB hybrid circuit composed of microstrip lines.
The output terminal D1 of the hybrid circuit 17 is connected to the front surface printed dipole element 32 via the microstrip 90-degree phase shifter 34, and the output terminal D2 is connected to the front surface printed dipole element 35.

One printed dipole antenna is formed by a front printed dipole element 32 and a back printed dipole element 33 arranged on both sides of an antenna substrate 31 made of a dielectric. Similarly, another printed dipole antenna is formed by the front printed dipole element 35 and the back printed dipole element 36.

The microstrip 90-degree phase shifter 3
The microstrip line 4 and the microstrip hybrid circuit 37 are also formed on a single substrate since the microstrip lines each having a foil-shaped conductor on one surface of the antenna substrate 31 as a double-sided substrate as a ground plane are used. be able to. The microstrip hybrid circuit 37 is actually configured as a branch line hybrid circuit or a rat race hybrid circuit. Accordingly, the entire bidirectional switching antenna device including the power supply circuit can be manufactured only by the printing technique, so that mass production becomes easy and cost reduction becomes possible.

[0034]

According to the present invention, the hybrid circuit 2
By selecting one of the input terminals and feeding power, the two element antennas can be excited in phase or in opposite phase.
As a result, two types of bidirectional patterns in which the directivity directions are shifted by 90 degrees in the horizontal plane can be realized only by selecting the terminals of one set of antennas. Therefore, the entire circumference can be covered by the switching control of one antenna.

In the present invention, all components can be configured on one double-sided board. That is, an antenna which can be manufactured only by the printing technique, has high quality, and is suitable for mass production is realized. Cost reduction is also easy.

[Brief description of the drawings]

FIG. 1 is a front view of a bidirectional switching antenna device according to a first embodiment.

FIG. 2 is a rear view of the bidirectional switching antenna device of FIG. 1;

FIG. 3 is a graph showing radiation characteristics of a horizontal plane of the bidirectional switching antenna device of FIG. 1;

FIG. 4 is a front view of a bidirectional switching antenna device according to a second embodiment.

FIG. 5 is a rear view of the bidirectional switching antenna device of FIG. 4;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Antenna board 12, 15 Front printed dipole element 13, 16 Back printed dipole element 14 90 degree phase shifter 17 Hybrid circuit 31 Antenna board 32, 35 Front printed dipole element 33, 36 Back printed dipole element 34 Microstrip 90 degree phase shift Vessel 37 microstrip hybrid circuit

Claims (3)

[Claims] 1. A bidirectional switching antenna device comprising a combination of a plurality of element antennas each having a substantially omnidirectional directivity in a horizontal plane, wherein the antennas are arranged in a horizontal direction at an interval of substantially half a free-space wavelength of a used frequency. At least two element antennas arranged, a 90-degree phase shifter connected to one of the two element antennas, and a 90-degree hybrid circuit having two output terminals respectively connected to the inputs of the two element antennas; A bidirectional switching antenna device comprising: 2. The bidirectional switching antenna device according to claim 1, wherein said element antenna is constituted by a foil-shaped dipole antenna formed on a dielectric substrate.
A bidirectional switching antenna device, wherein the 0-degree phase shifter and the hybrid circuit are formed of a foil-shaped conductor formed on the substrate. 3. The bidirectional switching antenna device according to claim 2, wherein said dipole antenna is formed by a first foil-shaped conductor formed along a front surface of said substrate and a second foil-shaped conductor formed along a back surface. And a foil-shaped conductor.