JPS6247263B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a radar device that uses an amplitude comparison monopulse method among devices that automatically angle-track flying objects such as rockets and artificial satellites. An example of a conventional device will be explained with reference to the drawings. FIG. 1 is a block diagram showing the circuit configuration of a conventional amplitude comparison monopulse type angle tracking device, and FIG. 2 is a front view of the radiant horn arrangement shown in FIG. 1. In Figure 1, the dotted line indicated by 1 indicates the monopulse coupler (power supply section), 2, 3, 4, and 5.
are horn A, horn B, horn C, and horn D, respectively, and 6, 7, 8, and 9 are polarization converter A, polarization converter B, polarization converter C, and polarization converter D, respectively. , 11, 12 and 13 are all magic Ts, 14 is a non-reflection terminator, 15 is a tracking receiver, and 16 is an antenna controller. Second
2, 3, 4 and 5 shown in the figure are the same as the same reference numerals in FIG. 1, and are respectively horn A, horn B,
Horn C and horn D are shown to represent their spatial arrangement. In Figure 1, horns A, B, C, and D
The electric field of the electromagnetic wave incident on the polarization converters A, B, and C
After the plane of polarization is converted by E and D, respectively
The electric fields are _A , E _B , E _C , and E _D , and the four magic Ts (symbols: 10, 10,
11, 12 and 13), the target angle tracking signals Σ, △AZ, △EL are
get. Here, Σ, △AZ and △EL become signals as shown in the following equation. These signals are processed by the tracking receiving device 15 and the antenna control device 16 in the latter stage, and the antenna device including the monopulse coupler 1 (not shown in the drawing) is always set to Σ=a (some value other than 0) and Operate so that △AZ=△EL=0 ......(iv). From equations (i), (ii), (iii), and (iv), the following conditions are obtained: E _A = _ED ≠0, E _B =E _C ≠0...(v). By the way, if the target exists on a line perpendicular to the aperture planes of horns A, B, C, and D from the intersection of the vertical line and the left and right lines in Figure 2, E _A = E according to the principle of monopulse radar. _B = E _C = E _D. In this case, △AZ=△EL=0...(iv), but in addition

[Formula] becomes. E _FL will be explained in a later section, but if we can obtain the condition E _FL = 0 in addition to the condition in equation (iv), the target will be captured by the main lobe of the antenna, as can be understood from Figure 2. It means that. However, in the conventional method, since the antenna is controlled only under the condition of equation (iv), E _FL ≠0 and ΔAZ=ΔEL=0. If there are no side lobes in the antenna's directional characteristics, if △AZ = △EL = 0, then E _FL = 0 naturally.
However, when the secondary lobe captures the target, a case occurs where ΔAZ=ΔEL=0 and E _FL ≠0. Therefore, depending on the conditions at the time of initial acquisition, (E _A = E _D ) ≠ (E _B = E _C ) ... (vi) But if (iv) △AZ = △EL = 0 is satisfied. can be tracked. The condition of formula (vi) means E _FL ≠0.
In this case, there are four or more automatic tracking pull-in points at positions obliquely deviated from the true angle due to the nature of the antenna radiation pattern, which necessarily has sublobes annularly distributed around the main lobe in addition to the main lobe. However, during automatic tracking, it is not possible to determine whether the main lobe is retracting to the true angle or the latter secondary lobe is retracting to the wrong angle, and if it is retracting to a false angle, a large tracking error will occur. However, it had a serious drawback in that it was unable to achieve its original purpose. This invention is based on the fact that, as mentioned above, when the angle automatic tracking device is retracted to a false angle, the angle may deviate greatly or the reception level may be low, causing serious problems. The authors have discovered a means to easily distinguish between objects that could not be determined to be caused by the angle of the object, and provide a method that can always accurately track angles. An embodiment of the present invention shown in FIG. 3 will be described in detail below. FIG. 3 is a block diagram of a circuit configuration showing an embodiment of the amplitude comparison monopulse type angle tracking device according to the present invention. In Figure 3, monopulse couplers (1 and 2, 3,...1
3) performs the same operation as explained with reference to FIG. 1, and obtains the desired Σ (sum signal), ΔAZ (azimuth angle error signal), and ΔEL (elevation angle error signal). Originally, in addition to these three signals for tracking, a signal called FL (abbreviation for False Lock) was obtained, but in the conventional method, this signal was not used and was led to a non-reflection terminator and discarded. In the present invention, this signal called FL is used to detect false acquisition, and its operation will be explained below. Signal voltage E _FL appearing at FL terminal
teeth, It is indicated by. If the target object is located at the center of the main lobe of the antenna (that is, if the true angle is captured correctly), then E _A = E _B = E _C = E _D , and E _FL becomes zero _, and the signal does not appear. (This corresponds to normal tracking.) However, if the target object comes in front of the directivity of the sublobe, it will be captured at a false capture angle. FIG. 4 is a pattern diagram of the antenna radiation pattern viewed from the front of the antenna axis. In Figure 4, AZ
The origin of the axis and EL axis is the center of the main lobe. The dotted line in the vicinity indicates the spread of the main lobe. Moreover, the dotted line with the larger radius centered on the origin indicates the ring of the sublobe. FIG. 5 is a cross-sectional view of the antenna radiation pattern including the central axis of the antenna shown in FIG. The main lobe, side lobe, X, etc. correspond to the same ones in FIG. 4, respectively. If there is a target object at each position marked by However, in this case, the above (vi)
By the formula In Although,

[Equation] Since E _A ≠E _B ∴E _FL ≠0, a signal appears at E _FL . Therefore, if E _FL is normalized and demodulated by Σ (sum signal) in the tracking receiver 15 shown in _FIG . You can immediately determine whether you are facing a false angle or a false angle. As can be seen in FIG. 5, there is not only one sublobe ring, but there are second, third, etc. rings further outside, but their effects are the same as described above. Although the case of the four-horn amplitude comparison monopulse system has been described above, the present invention is not limited to this, and can be applied to a five-horn amplitude comparison monopulse system based on the same principle. As described above, the false acquisition detection device according to the present invention has the advantage that if a flying object is tracked at a false angle, it can be detected immediately, so correct angle tracking can always be ensured by reacquisition etc. This also has the effect of giving the device operator a sense of security at all times even during normal tracking.

[Brief explanation of the drawing]

FIG. 1 is a circuit configuration block diagram of a conventional amplitude comparison monopulse angle tracking device, FIG. 2 is a front view of the horn arrangement in FIG. 1, and FIG. 3 is an example of an amplitude comparison monopulse angle tracking device according to the present invention. A circuit configuration block diagram showing an embodiment, FIG. 4 is a pattern diagram of the antenna radiation pattern seen from the front of the axis, and FIG. 5 is a sectional view including the axis of the antenna radiation pattern. In the drawing, 1 is a monopulse coupler (power feeding part), 2 is a horn A, 3 is a horn B, 4 is a horn C, 5 is a horn D, 6 is a polarization converter A, 7 is a polarization converter B, 8 is a polarization converter C, 9 is a polarization converter D, 10, 11, 12, and 13 are magic Ts, 14 is a non-reflection terminator, 15 is a tracking receiver,
16 is an antenna control device. Note that the same reference numerals in each figure represent the same or equivalent parts.

Claims (1)

[Claims] 1. The axis of the antenna of an amplitude comparison monopulse radar device having a swing drive device that drives the antenna around a vertical axis and an elevation drive device that drives the antenna around a horizontal axis in order to automatically angle track a target with the antenna. The target sensitivity captured by the beam deflected upward to the left from the direction is the first output, and the target sensitivity captured by the beam deflected upward right from the antenna axis direction is the second output. When the target sensitivity captured by the beam deflected downward to the left from the axis is the third output, and the target sensitivity captured by the beam deflected downward to the right from the axial direction of the antenna is the fourth output, 1
controlling the swing drive device of the antenna so that the sum of the output of the output and the third output is equal to the sum of the second output and the fourth output; controlling the elevation drive device of the antenna so that the sum with the second output is equal to the sum of the third output and the fourth output;
detecting the difference between the sum of the first output and the fourth output and the sum of the second output and the third output as a signal indicating false acquisition by a side lobe of the antenna; A tracking radar false acquisition detection method characterized by: