JPS59105576A - Radar equipment - Google Patents

Abstract

PURPOSE:To reduce clutter to achieve the enhancement of detection capacity, in a flight body-borne radar for performing electronical beam scanning, by such a simple constitution that the phase shift amount of an antenna element is controlled by operating and correcting a phase corresponding to a scanning mode. CONSTITUTION:An information treatment device 8 calculates third system phase data corresponding to the altitude from a radio wave altimeter 15 to store the same in the phase correcting amount memory circuit 12 of a beam scanning controller 9. When the repeated number of a medium pulse wherein a signal is embedded in side lobe clutter is selected in this state by a controller 1, a earthed switch 14 is changed over during a high pulse repeated frequency mode by the change-over signal (c) from the treatment device 8. By this mechanism, the phase correcting amount of the circuit 12 is added to the phase shift from a phase shift amount operation and controll circuit 10 in an adder 13 while the phase shift amount of the antenna element of a phased array antenna 4 is controlled and only the side lobe below main beam is lowered without deflecting an antenna beam width to a large extent. As a result, clutter due to the sea level and the ground level is reduced and the enhancement of detection capacity can be achieved.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a pulsed Doppler radar device mounted on a flying vehicle and performing electronic beam scanning; A phase correction amount storage circuit, an adder, and a switch are provided for pattern forming, and these are controlled by 111.
The phase shifter of the phased array antenna is
Anti (2) side lobe characteristics by side l? Control according to the radar operation mode to reduce clutter from the ground or from the target object 11
EII 1iP, a radar device that attempts to significantly improve VC? This is what we are trying to provide.

In a pulsed Doppler radar using a conventional phased array antenna or σ mechanical erosion antenna, the +J+IllV+'+ distribution' of the antenna element or array element is controlled in order to reduce the antenna side lobe ratio.

In passive phased array antennas or mechanical scanning antennas in which the antenna elements do not have any special functions,
Once the mll&1 distribution is set, the antenna pattern is determined at a glance, and its characteristics cannot be changed during operation as a radar. Furthermore,
Low sidelobe characteristics often have the drawback of decreasing antenna gain and reducing radar detection distance.

This invention was made to completely eliminate these drawbacks of conventional radar equipment, and has low sidelobe characteristics of 1g:
Instead of controlling the four widths to obtain the full width, a method of stopping the phase k · n + 1 is adopted, and a phase sleeve correction memory circuit is used in the beam scanning training device for (3) of the original beam scanning.

An adder and a switch are provided to completely control the altitude of the flying object or non-radar device from the radio altimeter. Phase Sodemasa Hotaru? By obtaining a third-order phase distribution on the antenna aperture curve, it is possible to reduce the sidelobes only in the lower part of the antenna main beam without causing the antenna main beam to become significantly unbalanced. clutter can be significantly reduced.

Therefore, it is an object of the present invention to provide a radar device whose target detection ability can be greatly improved even under a 9-force or rutter environment.

The conventional radar device and the radar device of the present invention will be fully explained below with reference to the drawings. FIG. 1 is a diagram showing an example of the configuration of a conventional radar device, in which (11 is a controller, (21 is a transmitter, (31 is a transmitter/receiver switcher, (41 is a phased array antenna, (5; is the reception 4'J3e, +61 is the signal processor, (71 is the indicator, (8) is the information processor, +91
ID beam (4) scanning +1111ii11 device, 0 port 1 is phase shift calculation control circuit, (111 drive circuit, Σ monopulse sum channel, Δ monopulse difference channel.

Since the configuration of the above-mentioned conventional radar device is as described above, the transmitter (21 generates a pulse-shaped transmission signal and the transmitter/receiver switch (31 Phased array antenna (4)
send to The transmitted signal is radiated into space from the phased array antenna (41), reflected by the target, received, and then input to the receiver +51K via the transmitter/receiver switcher (31), where it is amplified, mixed, and sent to the signal processor (61) as a video signal. Necessary processing is performed and displayed on the indicator (7).The output of the signal processor (6) is sent to the information processor (81) and is processed based on the target tracking command from the controller (1). The target tracking process is executed, and the accurate force distance, speed, and angle ↑H11 are displayed in symbols and numbers on the stick-out indicator (71).

One-way control B + 11 unit (Based on the field and beam scanning pattern selected in 11, the information processor (81 is a beam scanning angle command signal & all beam scanning controller + When I send it.

(5) The phase shift amount calculation control circuit (lO) calculates the amount of phase shift to be given to the phase shifters of the large number of antenna elements (not shown) that make up the entire phased array antenna (4), and
1) outputs a phase shifter drive signal to set the antenna cable shifter to full drive. As a result, the antenna main beam is directed in the command direction.

By the way, the search and tracking radar uses the pulse Doppler method to remove clutter from the ground, and the PRF (Pulse
A fully weighted quotient PRF method is used. Figure 2 is a diagram showing the operating principle of a conventional pulsed Doppler radar. As shown in Figure 2 (1), when the antenna main beam (20+ is target 1, F221 and target 2■) and the earth -) is fully irradiated, , reception 4': The spectrum of No. 4 is the second
As shown in Section 1(b), the main beam clutter and sidelobe clutter are spread out on the frequency axis.PRF:
Appears in tr9J:. Target 1 (
2) is received at a frequency fo + fdl higher than the transmission frequency f by the Doppler frequency Mfdt, so the main beam Clara (6) taQ! 1) and sidelobe clutter α;) are JM
They can be clearly separated in the wave number axis, and even if the antenna side lobe (211) is large, it is unnecessary and if the rack is removed, only the same approaching target can be produced. As shown in Figure 2 (b), the reception target number from the coming target 2nd day) is at a frequency fQ between the frequency of the main beam Claratum; and the transmission 1M wave number f.
10fd2, so the sidelobe clutter (2) is reduced to a large level by decreasing the transmission PRF%.
;). Therefore, for the target H23+, in order to reduce the overlap of sidelobe clutter Gil for each PRF, the value of PRF is completely lowered, and the PRF is adjusted to such an extent that the main beam clutter width 1 does not match l on the frequency axis. A medium PRF method with a high value is used. Fig. 2(e) Frequency spectrum of received signal in middle PRF mode? As shown in the figure, the tracking approaching target signal +
8 [The magnitude is almost the same as that of the sidelobe clutter (a). However, the power level of sidelobe clutter is proportional to the size of the transmitting and receiving antenna sidelobes, and increases inversely with altitude (7). If the height from the ground is low, the approaching target signal will be buried in sidelobe clutter and cannot be detected. Therefore, target reconnaissance-Q
In order to detect all of the idrobe clutter, it is necessary to further reduce the antenna sidelobes.

In this way, in the A PRF mode of a pulsed Doppler radar, even if the antenna side lobe is high, only clutter can be removed, so a high antenna gain is required to improve the target detection ability, and in the medium PRF mode, Even if the antenna gain decreases, it is required to lower the antenna sidelobes.

However, with conventional 2-aided array antennas and mechanically driven antennas, once the full aperture distribution has been set, the antenna pattern cannot be completely changed without physically modifying the height. I was measuring the fall of the robe.

However, since the antenna gain also decreases, there is a drawback that the l:1 target signal strength decreases.

(8) This invention focuses on the fact that clutter exists only below a radar device mounted on a flying object.

This is intended to reduce side lobes only at the main antenna and one point below.

An embodiment of the present invention will be described in detail below with reference to the drawings.

FIG. 3 is a diagram showing an embodiment of the present invention.

The feature of this invention is that a phase correction amount storage circuit f121, an adder (151) and a switch (14) are installed in the beam scanning controller (9) of the conventional radar device shown in FIG.

With a simple configuration that only uses the high W signal from the radio altimeter (15), the side lobe clutter below the antenna main beam can be reduced depending on the mode of the pulse Doppler radar.

The goal is to improve target detection ability. The phase correction amount storage circuit (12) stores cubic phase data d on the antenna aperture surface calculated by the information processor (81) in response to the high II signal H for a large number of antenna elements. Based on the beam scanning angle command signal a from the information processor (81), the shift/scale calculation control circuit outputs the total amount of modality required for each antenna system (9). Calculate. When the medium PRF mode is selected in the controller 1 (11), the switch (141) connects the adder (13) and the phase correction amount storage circuit (12I) by the switching signal C of the information processor (8). , the amount of phase shift for beam pointing and the amount of third-order phase correction are added for each antenna element by a Calo calculator (131), and the phase shift amount within the phased array antenna (41 antenna elements is calculated by the drive circuit 01). Fully powered.

Also, when the high PRF mode is selected with the controller (11).

The information processor (8) controls the switch (141) to
Since the terminal on the phase correction amount storage circuit +121 side of the adder +131 is grounded, the input to the adder becomes zero, and the output of the phase shift amount calculation control circuit passes through the adder +131k as it is and is sent to the antenna element from the drive circuit (11). phase shifter.

Figure 4 is a diagram showing the sidelobe reduction by the third-order system phase cuff used in this invention. Figure 4 (,) is the open curve amplitude distribution, and Figure 4 (b) is the third-order system. FIG. 4(c) is a diagram showing the phase distribution, and FIG. 4(c) is a diagram showing the antenna pattern when cubic phase correction is not performed and the antenna pattern when it is implemented. This diagram (lO) u 1961 McGraw-Hill 1 company in 2018! 7f
AntennaEngineerIng Ha
It is written in Chapter 2.11 of ndbook. As is clear from this figure, the sidelobe level of approximately -23dB is 3.
Approximately -36d for one side of the main beam due to secondary system phase correction
It decreases to B. Since clutter exists only below, the low sidelobe region may be located below the main beam. In other words, the horizontal line (x
11+), it is sufficient to provide a cubic phase distribution so that the upper phase lags and the lower phase advances. Even if antenna side lobes are present in the high PRF mode, it is easy to reduce the side lobes in the medium PRF mode by giving the antenna aperture a third-order phase distribution. characteristics can be obtained. On the other hand, with conventional radar equipment, approximately -3fidB
In order to obtain low sidelobe performance (f), it is necessary to make the amplitude distribution of the aperture plane equal to or higher than the square of the cosine function, and in this case, the aperture efficiency of the antenna is approximately -23
Compared to the aperture width distribution of the first power of the cosine function that obtains the sidelobe performance of dB, the radar's performance is reduced to about 82% ((n) -0.85 dB).

The radar device according to the present invention has a coefficient of about 90.

FIG. 5 is a diagram showing the effects of this invention.

Figure 5 (a) 1 in PRF pulse Doppler mode during td
1711, only the antenna main beam (antenna side lobe (21) below the row) is reduced, and the clutter reflected power from the ground is reduced.w
Figure 15(b) shows the received spectrum, and the sidelobe clutter c2B+ is reduced and the tracking approach target signal example is
The ability to detect targets larger than 1 with sufficient sidelobe clutter (a) even at a low level has been greatly improved.

Next, a method for calculating the third-order phase data d provided by the antenna aperture t&I K will be described.

The third-order phase data, that is, the value of the maximum phase amount β at the end of the antenna aperture shown in FIG. 4(b) is determined mainly by the altitude H of the radar device mounted on the spacecraft. Sidelobe clutter unit reception area average reception power p
sL is (12) K: Radar 'a element r (Thus, constant γ: Clutter reflection coefficient from the earth or sea surface G8L: Antenna side lobe average gain vR: Projectile horizontal flight speed H: Projectile object (radar 'yi) Geese) Altitude and Nashi, Altitude H
It is clear that the biggest change is caused by Here, since the horizontal flight speed VR of the projectile tends to change significantly during normal operation, and the clutter reflection coefficient r changes significantly depending on the type of aircraft, such as land or sea surface, we assume operation on sea surface. Then, since large %jK does not change, the average received power of sidelobe clutter P8L
keR becomes. As is clear from this equation, the antenna size (13
) If the trope average gain is changed by a factor of 11 relative to high [H], the sidelobe clutter received power will always be constant regardless of the altitude. Let us assume that the reference altitude H is the altitude at which the received power of sidelobe clutter is smaller than the thermal noise power generated by the radar receiver when the third-order phase distribution is not applied to the antenna aperture.

When the visibility H is higher than the reference altitude H, there is no need to lower the antenna sidelobe, and only when it becomes lower, 3
All that is required is to give the phase distribution of the order system. , and the maximum phase amount β at the edge of the aperture and the average gain of the lower side lobe of the antenna main beam should be precisely determined from the result of calculating the average power value of all the side lobes existing below. It is expressed by an approximate expression.

Therefore, as shown in Fig. 4(b), the phase correction factor φ1 given to each antenna cluster is as follows: At the ia intersection mark, φ1=-βyI3 ・・・・・・・・・・・・
・・・・・・・・・・・・・・・・・・＋41yi:i
The distance in the y-axis direction of the th antenna strand is zero at the antenna center and 1 at the antenna aperture end.

In this way, the information processor (8) compares the altitude signal H with the reference altitude and calculates the large phase amount β for the small platform.
The amount of phase correction φ1 to be given to each antenna element can be calculated. Therefore, as shown in Fig. 3, the altitude signal H from the radio altimeter 05) is always kept below the receiver thermal noise power level by the information processor (81 is the sidelobe clutter in Fig. 5(b)). In addition, the value of the maximum phase amount β to be given to each antenna cable is transferred to the phase correction amount storage circuit (121) and stored, and the third-order phase correction value φi to be given to each antenna cable is transferred to the phase correction amount storage circuit (121) and stored. By realizing a second-order phase distribution, it is possible to reduce sidelobe clutter even when the altitude decreases while performing full beam scanning, and the detection ability of targets that compete with sidelobe clutter on the frequency axis (
15) It is possible to significantly reduce the amount of chips.

As described above, according to the present invention, in a radar device that performs all beam definition electronically, the beam scanning row 9dl
It is a simple configuration that only requires a circuit, an adder, and a switch to record the phase correction amount on the antenna, and uses the altitude signal from the radio altimeter.It gives the entire third-order phase distribution on the antenna aperture surface and converts it to radar mode. Accordingly, it is possible to significantly improve the target detection ability in a rutter environment by reducing side lobes without completely degrading the radar distance performance.

[Brief explanation of drawings]

Fig. 1 is a diagram showing the configuration of a conventional radar device, Fig. 2 is a diagram showing the operation of the conventional radar, Fig. 3 is a diagram showing an embodiment based on the present invention, and Fig. 584 is a diagram showing the side lobe according to the present invention. The fifth factor is the operation and effectiveness of the radar based on the present invention;
(41 is a phased array antenna, (5I is a receiver. (6) is a signal processor, (71 is an indicator, (8) is an information processor. 9) Beam scanning controller a
4 parts + 1 i eye 1 device. (16) (11) is the drive circuit, t12) is the phase correction amount storage circuit, 03) is the adder, (14+ is the switch, f15+ is the radio altimeter, @j is the antenna main beam, and ) is the antenna side lobe. @ is goal 1. c! 'II is goal 2.
f241 is earth, main beam clutter, 弽) is sidelobe clutter, @ is oncoming approaching target signal, CI
! 81 is a tracking approaching target signal. Note that the same or corresponding parts in the two figures are designated by the same reference numerals. Agent Makoto Kuzuno (17)

Claims (1)

[Claims] In a pulsed Doppler type radar device that is controlled by a flying object and performs beam scanning electronically. a phase shift amount calculation control circuit that calculates the phase shift amount of a phase shifter of a large number of antenna elements constituting a phased array antenna;
a phase correction amount storage circuit that stores cubic phase data on the antenna aperture surface; a sword Ω calculator that adds the output of the phase shift i calculation control circuit and the output of the phase correction amount storage circuit; and the adder. and a switch-back device that connects the phase correction amount storage circuit and the phase correction amount storage circuit, and provides the output of the phase correction amount storage circuit to the sword shinki. A beam scanning control circuit that controls all of the phase shifters of a large number of antenna elements on the upper beam, and an antenna enclosure that controls the entire flight height of the projectile relative to the ground or direction according to the radar altitude signal from the ubiquitous altimeter that measures the flight height of the projectile relative to the ground or direction. A function of measuring the third-order phase theta given to the surface and storing it in the phase correction amount storage circuit, and generating a beam scanning A control signal to the phase shift n control circuit. In radar transmission mode where the target signal and sidelobe clutter compete on the frequency axis, a switching signal is generated to the switching device to perform phase correction.1! An information processor having a function of connecting the circuit and all of the 7JD calculators is provided, and the information processor is configured to process phase data for beam scanning from the phase shift calculation control circuit and third-order system phase data from the phase correction amount storage circuit. A radar device characterized in that a target signal that competes with sidelobe clutter on the frequency axis is detected by adding the signals using an adder to give a third-order phase distribution on the antenna aperture surface.