JPH03148081A - Radar equipment - Google Patents

Abstract

PURPOSE:To improve jamming resistance by providing a side-lobe cancelling means for forming a directive zero point in the arriving direction of an unwanted wave, and feeding back the data obtained through digital-beam forming antennas to the side-lobe cancelling means. CONSTITUTION:An opponent radar-wave analyzing device 16 and a jamming- wave generating device 17 accompanied by a target 15 are present in the direction of theta2. Then the side lobes in the direction of a transmitted beam theta2 emitted from a phased array antenna 3 are detected with the device 16. The frequency, the modulating method and the like of the transmitted wave are analyzed, and the powerful jamming wave which is equivalent to the transmitted wave is emitted from the device 17. When the observation of the target 15 becomes difficult by the jamming, digita-beam forming antennas 11 detect the arriving direction of the jamming wave and suppress the side lobes in the arriving direction of the jamming wave in the receiving beam as shown by a broken line based on an adaptive operation. Therefore, sensitivity for the jamming wave is strikingly decreased, and the effect of the jamming wave becomes hard to receive. The phase data are fed back to a side-lobe cancelling operation circuit 13 from a beam former 10, and the error is corrected.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a phased array antenna for transmission,
The present invention relates to a radar device that combines a digital beam forming antenna capable of forming multiple beams for reception, and particularly relates to improving its anti-jamming performance.

[Prior Art] Fig. 3 shows conventional radar devices of this type, such as those disclosed in Jikai Publication No. 167287/1983 and Japanese Patent Application Laid-open No. 167288/1983.
FIG. 2 is a block diagram showing a radar device disclosed in the publication.

In the figure, reference numeral 101 denotes a transmission pulse that is modulated as required and sent out from an oscillation circuit (not shown) and is divided into an arbitrary number of sub-pulses, which are divided into an arbitrary number of sub-pulses, and each phase shifter 101 of the first to n-th transceiver modules 201 to 20n, which will be described later. This is a transmission pulse division/distribution circuit that distributes and outputs each sub-pulse to 2011, and this division into sub-pulses is performed based on target number information transmitted from a reception beam processing device (not shown) of the radar device. Further, 102 is a transmission beam control circuit that separately sets and controls the phase shift amount of each phase shifter 2011 (1) (2) of the first to n-th transmitting/receiving modules 201 to 2On, which will be described later. The setting of each of these phase shift amounts is similarly performed based on target azimuth/distance information transmitted from the above-mentioned receiving beam processing device (not shown).

The first to n-th transmitting/receiving modules 201 to 20n are disposed corresponding to each of the element antennas 301 to 30n of the array antenna 300, and transmit a transmission beam to a target (not shown) through each corresponding element antenna. This is a module that performs radiation and reception of reflected waves from the target of the radiation beam. These modules are e.g.
Taking the first transmission/reception module 201 as an example, the sub-pulse train F added from the transmission pulse division/distribution circuit 101 is
A phase shifter 2011 performs phase shift processing on each of the sub-pulses in an amount corresponding to the command CI applied from the transmission beam control circuit 102, and each of the sub-pulses subjected to the phase shift processing is a transmission amplifier 2012 for amplifying;
Consists of circulator (transmission/reception switching device) 2013, etc.
These amplified sub-pulses are transmitted to the corresponding element antenna 301.
A circulator 2013 receives the reflected signal from the target received by the same element antenna 301 into its own module 201, and radiates the reflected signal (high frequency signal) to the target.
receiver 20 which demodulates the signal into an intermediate frequency signal corresponding to the same signal and separates it into element I and element Q containing amplitude information and phase information.
14, and an A/D converter 2 that quantizes the demodulated intermediate frequency signal for each element I and Q and converts it into a digital signal.
015, respectively. The digital signals (DI, DQ) thus converted are sent to the distribution circuit 400 as received data R, -R of each of these modules 201 to 20n.

The distribution circuit 400 divides the received data R1-R of each of the modules 201 to 20n into an arbitrary number (
In this example, the distributed reception data R1 to Rn are transmitted to (3) (4) first to m-th beam forming circuits 501 to 50m, respectively.

These beam forming circuits 501 to 50m are circuits that separately form receiving beams in desired directions by controlling the amplitude and phase contents as desired using the received data R□ to R1. Further, these beam forming circuits 501 to 50m have an adaptive function type that can suppress unnecessary waves while keeping the response to the desired wave direction constant.

As described above, in a radar device that combines a phased array antenna for transmission and a digital beam forming antenna that can form multiple beams for reception,
By dividing one transmission pulse into sub-pulses equal to the number of received beams and transmitting them in each target direction, and receiving the reflected waves from the target during the non-transmission period within the pulse repetition period, multiple pulses can be generated within the pulse repetition period. Targets in different directions can be observed.

In addition, in this type of radar device, the beam forming circuit 501
~50m digital adaptive calculation forms an auxiliary beam with controlled amplitude and phase in order to suppress unnecessary waves with respect to the main beam formed in the target direction, as shown in Figures 4 and 5. By subtracting this auxiliary beam component from the main beam, unnecessary wave components included in the side lobe region of the main beam can be suppressed. This allows ESM (Electronic
A radar wave analysis device called ECCM (Electronic Count Measurement) and ECCM (Electronic Count
In response to interference waves from a jamming device on the other side equipped with an interference wave generation device called er Measure), the system suppresses the side lobes in the direction in which the interference waves arrive while keeping the main lobe in the direction of the target as it is. It is possible to reduce the directional sensitivity and make it less susceptible to interference waves.

[Problems to be Solved by the Invention] Conventional radar devices of this type are configured as described above, but the side lobes of the transmission beam transmitted in the target direction cause radio waves to be transmitted to the target (5) ( 6) Easy to be intercepted and analyzed by ESM, resulting in

It is susceptible to interference by radio waves that have the same frequency as the transmitted wave and have an energy that is incomparably greater than the reflected wave from the target, and suppression of side lobes in the received beam alone has not been sufficient.

This invention was made to solve the above-mentioned problems, and an object thereof is to obtain a radar device with improved anti-jamming performance.

[Means for Solving the Problems] A radar device according to the present invention includes sidelobe canceling means that controls the phase of a phased array antenna to form a directional zero point in the direction of arrival of unwanted waves in the sidelobe region of a transmission beam. In addition, information for suppressing unnecessary wave components obtained from the digital beam forming antenna is fed back to the side lobe canceling means.

[Operation] In the present invention, since a directional zero point can be formed in the direction of interference wave arrival in the sidelobe region of the transmission beam, information is not given to the other party's ESM, making it less susceptible to interference. At this time, information for suppressing unnecessary wave components obtained from the digital beam forming antenna is fed back, and errors are corrected.

[Example] An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment in which the present invention is applied to a radar device equipped with array antennas for transmission and reception, respectively. In the figure, 1 is a plurality of element antennas arranged one-dimensionally or two-dimensionally, 2 is a phase shifter provided for each element antenna 1, and these constitute a phased array antenna 3, which can be used as a transmitting antenna. used. Reference numeral 4 denotes a beam scanning controller that scans the transmission beam with a narrow beam by controlling the amount of phase shift of each phase shifter 2 of the phased array antenna 3.

5 is an oscillation circuit provided as a transmission radio wave generation source from the phased array antenna 3; 6 is a power distribution unit that distributes the output of the oscillation circuit 5 to each phase shifter 2 of the phased array antenna 3; It is a vessel. Further, 7 is a plurality of element antennas arranged one-dimensionally or two-dimensionally, and 8 is provided for each element antenna 7.
9 is an A/D converter provided for each receiver 8 and converts the analog signal output from the receiver 8 into a digital signal; 10 is each A/D converter 9; By inputting multiple digital signals transmitted simultaneously from the source and performing digital calculations (digital signal processing) internally, a multi-beam (multiple receive beams) is created that distinguishes received radio waves from different directions for each direction. The element antenna 7 to beam former 10 constitute a digital beam forming antenna 11, which is used as a receiving antenna.

Note that, like the beam forming circuits 501 to 50m of the prior art, the beam former 10 also has an adaptive function that can suppress unnecessary waves while keeping the response to the desired wave direction constant. . 12 is the beam scanning controller 4. A timing controller 13 controls the operation timing of each A/D converter 9 etc. of the digital beam forming antenna 11 and synchronizes them. This is a sidelobe cancellation calculation circuit that calculates the phase distribution for forming a zero point, and the calculation result is sent to the beam scanning controller 4, which controls the amount of phase shift of each phase shifter 2 of the phased array antenna 3. . Further, 14 is a phase separation circuit that extracts phase information from the auxiliary beam formed to suppress unnecessary wave components by the adaptive calculation of the beamformer 10, and this phase information is transmitted to the side lobe cancellation calculation circuit 13.
The error in the phase distribution set by open loop calculation is successively corrected by detecting the arrival direction of the interfering wave. Note that 15 is a target on the other side to be observed, and 16.17 is an ESM and an ECM for interfering with observation of the target 15.

(9) (10) In this radar device configured as described above, by setting the phase shift amount of each phase shifter 2 of the phased array antenna 1 with the beam scanning controller 4,
Form a transmit beam with a narrow beam in the direction to target 15
In addition, on the digital beamforming antenna 11 side, a beamformer 10 performs digital calculations to form a reception beam with a narrow beam in the direction of 0, where the target 15 is located. It is possible to receive reflected waves from the target 15, observe information such as the position and speed of the target 15, and capture and track the target 15.

On the other hand, the opponent's ESMlG and ECM17 in accordance with Goal 15
exists in the 02 direction, the ESMlG detects the side lobe in the 02 direction of the transmission beam radiated from the phased array antenna 3, analyzes the frequency and modulation method of the transmission wave, and sends a signal from the ECM 17 that is equivalent to the transmission wave. It emits powerful interference waves. If this makes it difficult to observe target 15, digital beamforming antenna 1
1 detects the direction in which the interfering wave arrives and suppresses the side lobe of the received beam in the direction in which the interfering wave arrives, as shown by the broken line, so that the sensitivity to the interfering wave is significantly reduced and it becomes less susceptible to its influence. Furthermore, at the same time, on the phased array antenna 3 side, the sidelobe cancellation calculation circuit 13 calculates a phase distribution that forms a directional zero point in the direction of arrival of the interference wave by open-loop calculation, and outputs the phase distribution via the beam scanning controller 4. By controlling the array antenna 3, side lobes in the direction of interference wave arrival in the transmission beam, that is, in the 02 direction, are eliminated, making it difficult for the other party's ESMlG to intercept and analyze the transmission waves, and effectively generating interference waves. become unable to do so. In addition, this sidelobe cancellation calculation circuit 13 includes a phase separation circuit 14.
The phase information as a result of the adaptive calculation is fed back from the beamformer 10 via the beamformer 10 to correct the error, so the phased array antenna 3 follows the adaptive calculation of the digital beamforming antenna 11 (11). (12) Effectively controlled without delay. Furthermore, since side lobes are a major noise factor in radar, by suppressing side lobes not only in reception but also in transmission, the S/N ratio of the signal can be further improved.

By the way, the applicant has already disclosed a method of determining the excitation distribution to obtain a radiation pattern having a main beam and a directional zero point at a desired angle using a phased array antenna (Japanese Patent Application No. 118846/1983). This is shown using Figure 2. FIG. 2 1al is a pattern having a main beam at an angle θ1, and a zero point is synthesized at an angle 02. Figure 2 (bl is a radiation pattern with the main beam at angle 0□, and this reception level a1 is taken equal to the side lobe level a at angle 02 of Figure 2 (al). By superimposing the radiation patterns in FIGS. 2 and 2 with opposite phases, a radiation pattern having a main level at an angle of 0.0 and a zero point at an angle of θ2, as shown in FIG. 2 1al, can be obtained.

In the above embodiment, the present invention is applied to a device having array antennas for transmitting and receiving, respectively.
The same applies to the conventional example shown in the figure.

[Effects of the Invention] As described above, the present invention includes sidelobe canceling means that controls the phase of the phased array antenna to form a directional zero point in the direction of arrival of unwanted waves in the sidelobe region of the transmission beam. At the same time, the information for suppressing unnecessary wave components obtained from the digital beam forming antenna is fed back to the side lobe canceling means, so that even a phased array antenna can follow the digital beam forming antenna and eliminate side lobes in the direction of interference wave arrival. This has the effect that a radar device with improved anti-jamming performance can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of essential parts of an embodiment of the present invention, and FIG.
3) (14) Diagram showing the forming procedure, Fig. 3 is a block diagram showing the configuration of the conventional example, Fig. 4 fal, (b) shows the main beam and auxiliary beam obtained by the beam forming circuit shown in Fig. 3. Figure 5 shows the amplitude pattern of the beam, (bl is also a diagram showing the phase pattern of the main beam and the auxiliary beam. 1.7 is an element antenna, 2 is a phase shifter, 3 is a phased array antenna, 4 is a beam scanning controller, 10 is a beam former, 11 is a digital beam forming antenna, 12 is a timing controller, 13 is a sidelobe cancellation calculation circuit (sidelobe cancellation means), 14 is a phase separation circuit, 15 is a target, and 16 is a ESM, 17 is ECM.

Claims (1)

[Claims] A phased array antenna that performs beam scanning by controlling the phase is used for transmission, and a digital beamforming antenna that can form multiple beams is used for reception. A radar device that has a function of suppressing unnecessary wave components included in the side lobe region of the received beam, and controls the phase of the phased array antenna to suppress the directional zero point in the direction of unwanted wave arrival in the side lobe region of the transmitted beam. What is claimed is: 1. A radar apparatus comprising a sidelobe canceling means for forming a waveform, and information for suppressing unnecessary wave components obtained from a digital beam forming antenna is fed back to the sidelobe canceling means.