JPH0722829A - Array antenna - Google Patents

Abstract

PURPOSE:To scan the beam of an array antenna from a high elevation to a low elevation and to improve the gain for each elevation. CONSTITUTION:A first antenna (helical antenna) 10 having a conical beam directed to a high elevation position and a patch array antenna 20 consisting of plural second antennas (patch antennas 21 to 24) which are arranged around the first antenna 10 and have single-peak beams directed to low elevation angles are provided, and the first antenna 10 is fed from a synthesizing distributor 40 through a phase shifter 50, and second antennas 20 are selectively fed through a changeover switch 30, and beams of respective antennas are synthesized to set an arbitrary beam elevation.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an antenna used in mobile satellite communications and the like, and more particularly to an array antenna having a high degree of freedom in beam scanning in the elevation direction and an improved gain.

[0002]

2. Description of the Related Art Generally, an array antenna is used as an antenna for mobile satellite communication, and there is, for example, one in which a batch array is arranged on one plane. The array antenna having this configuration can scan the beam largely by controlling the power supply to the patch array, but there is a problem that the efficiency decreases at a low elevation angle. Therefore, in recent years, a system in which a patch array is arranged on a conical surface has been proposed. In this configuration, since the conical surface is oriented to a predetermined elevation angle in advance, the efficiency at a low elevation angle can be improved by appropriately setting the elevation angle.

[0003]

However, in the array antenna having the conical surface configuration, the patch array is arranged in the circumferential direction along the conical surface, so that the beam scanning cannot be performed in the elevation angle direction. There's a problem. It is an object of the present invention to provide an array antenna that enables beam scanning from a high elevation angle to a low elevation angle and has an improved gain at each elevation angle.

[0004]

An array antenna according to the present invention is provided with a first antenna having a conical beam and a first antenna which is disposed around the first antenna and has a required elevation angle with respect to the first antenna. A plurality of second antennas having a single-peak beam, a means for feeding power to the first antenna and the second antenna, and a phase shift means for changing the feeding phase between the first and second antennas. Equipped, first and second
It is possible to set each beam elevation angle by synthesizing each beam of the antenna. Here, the beam peak of the first antenna is directed to the high elevation position, and the beam peak of the second antenna is directed to the low elevation position to enable scanning of the beam elevation from high elevation to low elevation. Further, the second antennas are arranged in the same direction in all azimuth directions, and a single or a plurality of units are selected for power supply, so that the beam can be set in any direction. For example, the first antenna is a helical antenna and the second antenna is a conical patch array antenna.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described with reference to the drawings. FIG. 1 is an external perspective view of an embodiment of the present invention, in which a helical antenna is used as an antenna having a cone beam and a patch array antenna is used as an antenna having a unimodal beam. The helical antenna 10 has its spiral axis oriented vertically and forms a conical beam. The conical beam has a very low radiation level in the direction of the zenith Z axis, has a beam peak in the direction of the elevation angle θ1, and is a beam that radiates in all directions in the azimuth direction. Further, the elevation angle θ1 can be adjusted by adjusting the spiral pitch and the spiral length. Further, the patch array antenna 20 has a plurality of apex angles whose apex angle is larger than the aforesaid angle θ1. The patch antennas 21 to 24 are included. Here, an example is shown in which four patch antennas 21 to 24 are equally arranged in the azimuth direction. The patch array antenna 20 is a unimodal beam having a beam peak in the vertical plane direction of each of the patch antennas 21 to 24.

As shown in the schematic structure of FIG. 2, the four patch antennas 21 to 24 are connected to the combiner / distributor 40 via the four-beam changeover switch 30. It is configured to selectively supply power to. Further, the helical antenna 10 is connected to the combiner / distributor 40 via a phase shifter 50, and the phase shifter 50 is adjusted to feed power to the patch array antenna 20 at an arbitrary phase difference. Configure to do.

According to this configuration, the helical antenna 10 is fed with power through the combiner / distributor 40, and at the same time, the patch antennas 21 to 2 selected via the changeover switch 30.
Power to 4. As a result, as shown in FIG. 3, the beam B1 formed in the azimuth direction at the elevation angle θ1 formed by the helical antenna 10 and the beam B2 formed in the predetermined direction at the elevation angle θ2 formed by the selected patch antenna are combined. , As a result, the combined beam B3 of a predetermined azimuth at an elevation angle θ3
Is set as. At this time, the elevation angle θ of the combined beam B3
3 and its beam shape are determined by the phase difference between the beams B1 and B2 and the feed power ratio, but the feed power ratio is initialized by the combiner / distributor 40. Therefore, the phase amount in the phase shifter 50 should be adjusted. The feed phase of the helical antenna 10 is relatively changed with respect to the feed phase of the patch array antenna 20, so that the elevation angle θ3 of the combined beam B3 is changed.
Also, the beam shape can be changed arbitrarily.
Further, it is possible to change the azimuth of the combined beam B3 by switching the changeover switch 30 to change the patch antenna for feeding power.

Therefore, if the elevation angle θ1 of the beam B1 from the helical antenna 10 is set to an angle close to the zenith and the elevation angle θ2 of the beam B2 from the patch array antenna 20 is set to an angle close to horizontal, the elevation angle of the composite beam B3 is lowered. It is possible to scan over a range of angles to high angles. Further, by selecting the patch antenna, it is possible to set the azimuth in any direction. In the above configuration, an example in which the patch array antenna is composed of four patch antennas is shown for simplification of description, but it may be composed of a larger number of patch antennas, and the beam azimuth is set more finely. can do. Further, each patch antenna is selectively switched individually, but it is also possible to sub-array adjacent patch antennas and select them at the same time to supply power, or to supply power to all patch antennas at the same time. May be.

FIG. 4 is an external view of another embodiment of the present invention. Here, an example is shown in which a patch antenna 10A that generates a higher-order mode and radiates a conical beam is used as an antenna having a cone beam, and a patch array antenna 20A is used as an antenna that has a unimodal beam. That is, a single cone beam patch antenna 11 is arranged on the top surface of the truncated cone surface, and a plurality of (eight in this case) unimodal beam patch antennas 21 to 28 are arranged on the cone surface.
Then, similarly to the example shown in FIG. 2, the conical beam patch antenna 11 is fed with power through a phase shifter similarly to the helical antenna of the above-described embodiment, and the plurality of single-peak beam patch antennas 21 to 28 are switched. By feeding power via the beam, a beam obtained by combining both beams can be obtained, and the beam elevation angle can be arbitrarily set by adjusting the phase shift amount of the phase shifter. The synthesis of this beam is the same as that shown in FIG. 3, and the synthetic beam B3 can be set to an arbitrary beam elevation angle θ3. Further, it is also possible to arbitrarily set the beam azimuth by switching the changeover switch and selecting the patch to which power is supplied.

[0010]

As described above, according to the present invention, the first antenna having the cone beam and the plurality of second antennas having the unimodal beam arranged around the first antenna and having the required elevation angle are formed. , And the feed phases for both antennas are arbitrarily changed, the beams of both antennas can be combined to obtain an arbitrary beam elevation angle. In particular, by directing the beam peak of the first antenna to a high elevation position and the beam peak of the second antenna to a low elevation position, it is possible to scan the beam elevation angle from a high elevation angle to a low elevation angle, and It is possible to improve the gain at elevation. Further, by arranging the second antennas equally in all azimuth directions and selecting a single unit or a plurality of units for power supply, it is possible to set the beam in an arbitrary direction.

[Brief description of drawings]

FIG. 1 is an external perspective view of a first embodiment of the present invention.

FIG. 2 is a schematic configuration diagram showing a feeding circuit of the antenna of FIG.

FIG. 3 is a directivity diagram showing beam combination and beam elevation angle setting.

FIG. 4 is an external perspective view of a second embodiment of the present invention.

[Explanation of symbols]

 10 Helical Antenna 10A Conical Beam Patch Antenna 20 Patch Array Antenna 20A Patch Array Antenna 21-28 Patch Antenna 30 4 Bim Changeover Switch 40 Combined Distributor 50 Phase Shifter

Claims (4)

[Claims] 1. A first antenna having a cone beam,
It is placed around this first antenna,
The first antenna includes a plurality of second antennas having a unimodal beam forming a required elevation angle, the first antenna and the second antenna.
Means for supplying power to the respective antennas, and first and second means
An array antenna comprising: a phase shift means for changing a feeding phase between the antennas. 2. The array antenna according to claim 1, wherein the beam peak of the first antenna is directed to a high elevation position and the beam peak of the second antenna is directed to a low elevation position. 3. The array antenna according to claim 1, wherein the second antennas are equally arranged in all azimuth directions, and power is supplied by selecting a single unit or a plurality of units. 4. The array antenna according to claim 1, wherein the first antenna is a helical antenna and the second antenna is a conical patch array antenna.