JP2959220B2 - Electronic scanning antenna - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic scanning antenna of a secondary surveillance radar or a primary surveillance radar provided with a secondary surveillance radar, and more particularly to an electronic scanning antenna having a cylindrical array antenna.

[0002]

2. Description of the Related Art Conventionally, an antenna of this type excites a part of a plurality of column arrays arranged in a cylindrical shape, and scans a directional beam in an azimuth direction by switch control. Also, as a radar for air traffic control, a so-called fan beam having a wide beam width in a vertical plane and a narrow beam width in a horizontal plane is generally used. The case where the fan beams are formed in a cylindrical array and the equal phase plane is set in the horizontal direction will be described with reference to FIG. FIG. 2A is a conceptual diagram showing the observation elevation angle of the cylindrical array 10, and FIGS. 2B and 2C are conceptual diagrams showing the azimuthal phase relationship at elevation angles of 0 ° and θ °, respectively. 3 shows a state in which only the excitation sector 13 is excited. Also, the horizontal cross section 14 of the cylindrical array in FIG. 3B is substantially circular, while the cross section 15 parallel to the elevation angle θ ° in FIG. 3C is elliptical.

When the flat equal phase plane 11 is set at an elevation angle of 0 °, the horizontal beam width at an elevation angle of 0 ° becomes minimum as compared with the horizontal beam width at other elevation angles. The equi-phase plane having another elevation angle cannot be corrected for a phase difference corresponding to an elliptical cross section like the equi-phase plane 12 shown in FIG. The elevation characteristics of the horizontal beam width when a flat equal phase plane is formed at an elevation angle of 0 ° are shown by curve A in FIG.
Indicated by The horizontal beam width produces significant expansion at high elevation angles.
Conventionally, as an improvement means, for example, a flat equiphase surface is set at an elevation angle θ ° so that the horizontal beam width becomes the narrowest at the elevation angle θ °, and the improvement is somewhat improved as shown by a curve B in FIG.

As such a cylindrical column array,
Conventionally, there is one shown in FIG. That is, the column array 20 ₁ to 20 ₂₄ of 24 which are arranged in a cylindrical shape, eight S
P3T (Single Pole 3 Throw) switch 21 _{1 to} 21
A switch matrix 24 consisting of ₈ and butt color matrix 23, eight phase shifters 25 ₁ to 25 _8, and the power divider 26 is constituted by transmitting and receiving unit 27. In this configuration, SP3T switch 21 ₁ to 21 _8, 4
When a connection state shown in the column array 20 ₁ to 20
₈ is excited, radially through the center of the fan-shaped portion constituted by a column array 20 ₁ to 20 ₈ (the direction of arrow C)
A single main beam is formed. At this time, the Butler matrix 23 is controlled so that the output power of the power distributor 26 is distributed to a predetermined column array.

[0005] The phase shifter 25 _to 253 ₈ are used to correct the excitation phase distortion generated in the antenna aperture plane by mainly column array 20 ₁ to 20 ₂₄ are arranged in a cylindrical shape. The power distributor 26 is for providing a uniform or desired power distribution to each column array.
In FIG. 4, the control unit for controlling the switch matrix 24 and the phase shifter 25 _to 253 ₈ are omitted.
In addition, the switch matrix 24 and the column array 20 ₁ to
Connection between 20 ₂₄ are omitted certain disclosures to avoid complication.

[0006] When performing beam scanning, as well as to sequentially switch the state of the switch of the SP3T switch 21 ₁ to 21 _8, by controlling the state of the transfer switch 22 _{1-22 12} in the vat color matrix 23, without the order of output of the phase shifter 25 _to 253 ₈ are switched, it is possible to scan the beam in the circumferential direction. The connection state of the transfer switches 22 _{1 to} 22 ₁₂ can be set to any of FIGS. 5A and 5B by a control signal from a control unit (not shown).

[0007]

However, the conventional electronic scanning antenna has a problem that the azimuth accuracy is degraded and the gain is degraded because the horizontal beam width is expanded except at a specific elevation angle. An object of the present invention is to solve this problem and to provide an electronic scanning antenna which has high azimuth accuracy in a wide elevation angle range and can suppress a decrease in gain.

[0008]

An electronic scanning antenna according to the present invention comprises: a transmitting / receiving unit; a plurality of column arrays arranged in a cylindrical shape for performing beam scanning based on input power; and control means for controlling beam scanning. A power distribution unit including a distributor for distributing the power output from the transmission / reception unit and a phase shifter for adjusting the phase of the output of the distributor based on the control of the control unit, and a column array based on the control of the control unit. Switch means for providing the output of the power distribution means, and processing means for extracting the target altitude information or elevation information, and the control means determines the phase of the transmitted or received radio wave in accordance with the target elevation angle. The phase shifter to match in the plane perpendicular to the elevation angle
Then, the horizontal beam width is controlled in accordance with the target elevation angle .

[0009]

According to the present invention, the horizontal beam width can be narrowed and the azimuth accuracy can be improved by controlling the phase shifter according to the target elevation angle by the control means.

[0010]

Next, the present invention will be described with reference to the drawings. FIG. 1 is a block diagram of an electronic scanning antenna according to an embodiment of the present invention. In the figure, the electronic scanning antenna, a transmitting and receiving unit 4, a plurality of column arrays 1 ₁ to 1 ₂₄ for beam scanning based on the power to be input are arranged in a cylindrical shape
And a control unit 5 as control means for controlling beam scanning.
If a power distribution means 3 including a divider 26 and a control unit phase shifters 25 ₁ to 25 ₈ for adjusting the phase of the output of the divider 26 based on the control of the 5 distributes the power output of the transmitting and receiving unit 4,
The switch unit 2 that selects the column array 1 based on the control of the control unit 5 and supplies the output of the power distribution unit 3, and converts the target altitude information from the transmission / reception unit 4 into an elevation angle viewed from the antenna, and and a processing unit 6 which transmits the control data of the phase shifter 25 _to 253 ₈ to. The switching means 2 and the SP3T switch 21 ₁ to 21 _8, includes a batt color matrix 23.

Then, the altitude information sent from the target aircraft is received by the transmitting / receiving unit 4 and converted into an elevation angle by the processing unit 6. Moreover, calculating the data for controlling the phase shifter 25 _to 253 ₈ to equiphase surface in the lateral direction in the elevation angle becomes flat, encodes and sends to the control unit 5. Control unit 5 sends the data from the processing unit 6 in place of the control data for only the standard setting of the elevation angle theta ° described in the prior art when receiving the data from the processing unit 6 to the phase shifter 25 _to 253 ₈ It is configured as follows.

Therefore, the horizontal beam width can be narrowed according to the target elevation angle, and the azimuth accuracy can be improved in a wide elevation angle range. Note that the present invention is not limited to a system that can obtain altitude information from an aircraft, such as a secondary surveillance radar, and that the altitude information is transmitted to an electronic scanning antenna for a primary radar that is usually provided along with a secondary surveillance radar. Can be applied.

[0013]

As described above, the present invention comprises processing means for extracting altitude information or elevation information of a target, and control means for controlling the phase of a transmitted or received radio wave according to a target elevation angle by a predetermined elevation angle. The phase shifter is controlled so that the phase shifter is adjusted in the plane perpendicular to the plane, so the horizontal beam width can be narrowed according to the target elevation angle, the azimuth accuracy can be improved over a wide elevation angle range, and the gain reduction is prevented. There is an effect that can be.

[Brief description of the drawings]

FIG. 1 is a block diagram of one embodiment of an electronic scanning antenna of the present invention.

FIG. 2 is a conceptual diagram illustrating a cylindrical array.

FIG. 3 is an elevation characteristic diagram of a horizontal beam width of a cylindrical array.

FIG. 4 is a block diagram of a conventional electronic scanning antenna.

FIG. 5 is a diagram illustrating a function of a transfer switch of a conventional electronic scanning antenna.

[Explanation of symbols]

1 ₁ to 1 ₂₄ column array 2 switching means 3 power distributing means 4 receiving unit 5 control unit 6 processing unit 21 ₁ through 21 ₁₂ SP3T switch 23 butt color matrix 25 _to 253 ₈ phase shifter 26 distributor

Continuation of the front page (58) Field surveyed (Int. Cl. ⁶ , DB name) G01S 7/00-7/42 G01S 13/00-13/95 H01Q 3/26-3/42

Claims (1)

(57) [Claims] 1. A transmitting / receiving unit, a plurality of column arrays arranged in a cylindrical shape and performing beam scanning based on input power,
Control means for controlling beam scanning, power distribution means including a distributor for distributing the power output by the transmitting and receiving unit and a phase shifter for adjusting the phase of the output of the distributor based on the control of the control means, Switch means for selecting the column array based on the control of the control means and providing an output of the power distribution means; and processing means for extracting target altitude information or elevation information, wherein the control means The phase shifter is controlled so that the phase of a transmission or reception radio wave is adjusted in a plane orthogonal to a predetermined elevation angle in accordance with the elevation angle of
An electronic scanning antenna configured to control a horizontal beam width in response to the request .