JPS6057281A - Radar equipment - Google Patents

Abstract

PURPOSE:To form an extremely wide elevation angle covering area by adding a sub-electronic scanning array antenna for sharing in a high elevation angle covering area, to an electronic scanning array antenna. CONSTITUTION:An electronic scanning antenna B consisting of a primary radiator 1B, a phase shifter 2B and a distributor 3B is added to an electronic scanning antenna A consisting of a primary radiator 1A, a phase shifter 2A and a distributing circuit 3A, and both of them are switched by a switch 16. In this state, in accordance with a beam scanning timing from a generating circuit 7, a controlling circuit 5 controls an antenna switching timing basing on a beam scanning angle command and a timing, executes an arithmetic of a phase shifting quantity of a phase shifter 2 by synchronizing with said control, and controls the switch 16 and the phase shifter 2 through a driving circuit 17 and 4, respectively.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a parader device that realizes wide elevation angle coverage detection capability in an electronically scanned array radar that mechanically rotates in the horizontal direction while performing electronic beam scanning in the vertical plane. It is something.

Typical examples of electronically scanned array radar include phase scanned array radar, frequency scanned array radar, phase and frequency composite array radar, etc.; however, for convenience of explanation, they are shown in Figure 1. It has a configuration shown in FIG.
The following explanation will be given by taking as an example a conventional phase scanning array radar device that performs beam scanning shown in FIG.

The conventional radar device shown in FIG. 1 will be explained. The first intermediate frequency transmission type signal and the first local oscillation frequency generated by the reference signal generation circuit (7) are frequency-mixed by the transmitter (6) to become a transmission signal, which is then distributed via the transmission/reception switch (8). It is divided into n parts by the circuit (3), given a predetermined amount of phase shift by the phase shifter (2), and radiated into space from the -order radiator (1).

The phase shift setting amount of the phase shifter (2) described above is determined for each phase shifter (2) by the beam control circuit (5) based on the beam scanning angle command and timing from the reference signal generation circuit (7). It is calculated correspondingly and given via the drive circuit (4).

The transmission signal radiated in a predetermined direction in this way is partially reflected by the target, which includes a -order radiator (1), a phase shifter (2), a two-way distribution circuit (3), and a transmission/reception switch (8). ) becomes the receiver system input.゛First, it is amplified with low noise in the high frequency amplifier circuit (9), mixed with the first local oscillation frequency from the reference signal generation circuit (7) in the first mixing circuit α0, and converted into a first intermediate frequency signal. In the second mixing circuit oa, the signal is mixed with the second local oscillation frequency from the reference signal generation circuit (7) and converted into a second intermediate frequency signal, which is input to the moving target detection circuit 0■. The moving target detection circuit @ is generally referred to as MTI and detects unnecessary reflected waves (clutter) from the ground surface, weather, etc. in response to the transmission pulse repetition frequency generated by the reference signal generation circuit (7). It forms a filter that erases the .

The received signal with clutter suppressed is processed by the signal processing circuit 041
The signal is sent to the 2-display circuit αG, and the target information is detected and 2-displayed.

As described above, the intermediate frequency is not limited to two stages, but may be appropriately selected from one stage, three stages, etc. as necessary.

As described above, an antenna beam pattern is formed in a predetermined direction.
As shown in FIG. 2, the beam elevation angle direction is changed sequentially by time division to electronically scan a required elevation angle range, and FIG. 8 shows the relationship between transmission timing and beam position within one elevation angle scanning period.

In Fig. 8, the horizontal axis is time, and in order to efficiently distribute transmission energy, each transmission pulse has a constant transmission peak output, and the pulse width is made to correspond to the elevation angle to determine the maximum detection distance. In order to be satisfied, the angle is widened at low elevation angles and narrowed at high elevation angles. Depending on the transmission/reception format, there is also a method in which the pulse width is constant and the transmission peak output changes in accordance with the elevation angle, but in any case, this can be covered by the present invention and is not essential, so it will not be discussed here. The explanation will now proceed assuming that the transmission peak output is constant.

Within one elevation angle scanning period, beams are formed sequentially from low elevation angles to high elevation angles (#1) to (#n).
There are various other scanning methods, such as a method of scanning from a high elevation angle to a low elevation angle, and a method of scanning in a special sequence. However, since this is also not essential to the subject of the present invention, the explanation here will be based on the assumption that the beam is formed sequentially from a low elevation angle to a high elevation angle as described above.

The beam of (#1) is transmitted m times with a transmission period Tl, and
The beam of 2) is transmitted m times with a transmission period T2, and the beam of Ui) is transmitted with a transmission period of Ti'''cm.
H#...p Tn will be transmitted once each, and one elevation scan period is m (T1+T2+...+Ti)+T
i+1+...+Tn.

(#l) to (#i) The reason why the number of transmissions between the beams is set to m is that the clutter reception level is high in the low elevation angle region, so the moving target detection circuit a″4 m pulse cancellation M
This is to suppress clutter by forming a TI filter.

Further, T1 to Tn are the minimum times required for the radio waves to travel back and forth over the required detection distance.

Conventional electronically scanned array radar devices are configured as described above, and use primary radiators (1) arranged in a linear, planar, or curved shape as the electronically scanned array antenna. In any case, as the beam radiation direction moves away from the front direction, the antenna performance (gain, etc.)
This made detection over a wide range of elevation angles difficult.

In the case of the conventional planar array antenna shown in Fig. 4 axis),
The directivity pattern (electric field) of the -order radiator (1) is Ee(
01) ~6i "* denoted by Ee(θ2) = M,
If we focus on θl, we can approach θ1 → 90° and Ee(
θ1) → approaches 0.

The present invention has been made to eliminate the drawbacks of the conventional ones as described above, and has been made in combination with another electronically scanned array antenna whose vertical coverage area partially overlaps or does not overlap at all. The object of the present invention is to provide a radar device that enables wide elevation angle covert detection (including hemispherical cover area) by switching antennas.

Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

Figure 4 (6) shows the conventional main electronic scanning array antenna.
This is an example of the case where the secondary electronic scanning array antenna is ■, and ■ is responsible for the low elevation angle coverage area and ■ is responsible for the high elevation angle coverage area, and (ELmin)B <;h (ELmax)A. By doing this, the total elevation angle coverage is (ELmin)A~(EL
max)n.

FIG. 6 shows an embodiment of the radar device according to the present invention, in which the antenna changeover switch 0Q is used to control the electronic scanning antenna A (primary radiator (IA phase shifter (2A)), distribution circuit (8A )) and electronic scanning antenna B (consisting of a primary radiator (IB), a phase shifter (2B), and a distribution circuit (8B)); the rest is the same as the configuration shown in Figure 1. .

FIG. 6 shows the concept of beam scanning in the elevation plane.

FIG. 7 shows this beam scanning timing.

Figure 6(,) shows the vertical in-plane scanning of main antenna A, and (b)
shows the vertical in-plane scanning of subantenna B.

In the present invention, as shown in FIG. 4, the gain maximum elevation angle C(ELO)A) of the conventional (main) electronically scanned array antenna which is responsible for low elevation angle suppression, the high elevation angle (ELo)
By adding a sub-electronically scanned array antenna with maximum gain elevation angle B and combining both into the same rotating structure, the elevation angle coverage −(ELmi
n)A to (ELmax)A: Electronically scanned array antenna A ◆(ELmin)B to (ELmax)n: Electronically scanned array antenna B.

At this time, in order to perform the above operation, in FIG. 5, the reference signal generation circuit (7) generates a beam scanning angle command and timing according to the beam scanning timing shown in FIG. 7 as an example, and the beam control circuit (5) generates a Upon receiving this signal, the antenna switching timing is controlled, and in synchronization with this, the phase shift amount of the phase shifter (2) is calculated, and the switch drive circuit a'I)
The antenna changeover switch αQ is switched through the phase shifter drive circuit (4), and the phase shifter (2) is controlled through the phase shifter drive circuit (4).

At this time, the antenna changeover switch αQ needs to be switched in synchronization with the vertical beam scanning, and since it handles transmission power, a high-speed, high-power switch is required, and it is difficult to reduce the leakage power of the switch. . This leakage power prevents unused antennas from receiving signals (leakage power is emitted from unused antennas to prevent signals from short-range targets and/or targets with large radar cross sections (including flutter from the ground, sea surface, etc.) In order to receive reflected power with an antenna that does not use it and prevent it from being input to the receiving system due to leakage of the antenna changeover switch, the beam control circuit (5) changes the phase of the phase shifter (2A) or (2B) on the side that is not used. to prevent beam formation.

7(a) shows the beam scanning timing in the vertical plane of the main antenna A, FIG. 7(b) shows the beam scanning timing in the vertical plane of the sub antenna B, and FIG. 7(C) shows the switching timing of the A and B antennas.

Other operations are the same as those shown in FIG. 8, so their description will be omitted.

The above explanation has been given using the phase scanning array radar device as an example, but the frequency scanning array radar device has been explained as an example.

It is clear that the present invention can also be applied to electronically scanned arrays and radars in general, such as phase/frequency composite arrays and radars.

However, the method of preventing false target reception by not forming unused unfocused beams is limited to radars that form beams by phase control.

Furthermore, regarding vertical beam scanning, the explanation was given by taking as an example a method of scanning from a low elevation angle to a high elevation angle, but this is a method of scanning from a high elevation angle to a low elevation angle.

The present invention can also be applied to a special sequence or random scanning method.

As described above, according to the present invention, an electronically scanned array radar is configured such that a secondary electronically scanned array antenna that shares high elevation angle cover is added to a conventional (main) electronically scanned array antenna, and both antennas are By synchronizing switching and beam scanning and scanning within each elevation angle coverage area, it has become possible to achieve an extremely wide elevation angle coverage area.

Furthermore, in actual implementation, when the invention is applied, it is also possible to prevent reception of false targets due to leakage power from the antenna changeover switch by setting the phase so that the beams of unused antennas are not formed. .

[Brief explanation of drawings]

FIG. 1 is a functional diagram showing an example of the configuration of a conventional electronically scanned array radar, FIG. 2 is a conceptual diagram showing beam scanning related to vertical in-plane obliteration using the configuration of FIG. 1, and FIG. ,
A diagram showing an example of transmission timing for performing beam scanning shown in FIG. 2, and FIG.
A conceptual diagram of elevation angle subversion in the child scanning array antenna and the (main/sub) electronic scanning array antenna of this invention, FIG. 5 is a functional system diagram showing an example of the configuration of this invention,
FIG. 6 is a conceptual diagram showing beam scanning regarding a vertical in-plane coverage area by the configuration of FIG. 5, and FIG. 7 is a diagram showing an example of this beam scanning timing. In the figure, (IA), (2A), (8A) are the primary radiator of the main antenna, the phase shifter 2 distribution circuit, (IB), (2B
), (8B) is the primary radiator of the sub-antenna, phase shifter 2 distribution circuit, (5) is the beam control circuit, (7) is the reference signal generation circuit, (8) is the transmitter/receiver switch, and αQ is the antenna switch. The switch aη is a switch drive circuit. Note that the same reference numerals in each figure indicate the same or corresponding parts. Agent Masuo Oiwa. (θ) Figure 6 (EL-, 1 Mr. Commissioner of the Japan Patent Office 1. Display of the case Japanese Patent Application No. 58-166127 2 Name of the invention Radar device 3 To the person making the amendment Representative Hitoshi Katayama Department 4 Attorney 6; Subject of amendment (1) Detailed description of the invention column in the specification (2) Drawing 6, amended as follows (υ The description is corrected as follows. (2) Figure 2 of the drawings is corrected as shown in the attached sheet. 7. List of attached documents (υFigure 2 1 or more copiesFigure 2)

Claims (2)

[Claims] (1) In an electronically scanned array radar that mechanically rotates in the horizontal direction while electronically scanning the beam in the vertical plane, a main antenna that scans a part of the vertical cover;
The sub-antennas that scan at least the other part of the vertical cover are mechanically fixed to each other, mechanically rotated around the same rotation axis in a horizontal plane, and beam scanning is switched between both antennas. radar equipment. (2) The radar device according to claim 1, wherein the main antenna and the auxiliary antenna are phase control antennas, and the phase of the antenna that is not used is adjusted so as not to form beam rays.