Amplitude comparison angle measurement

Student number: 21021210936

College: School of Electronic Engineering

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Principle of amplitude comparison and angle measurement: using different but mutual directions? The same overlapping beam receives the target echo at the same time, and the accurate angle between the two beam directions is judged by two different echo amplitudes.

If the target is in the direction of the overlapping axis OA of the two beams, the signal intensities received by the two beams are equal. If the target is in the OB or OC direction, the signal strength received by one beam is higher than that of the other [35]. At this point, we can judge that the target deviates from the direction of the equal signal axis by comparing the echo intensity of the two beams.

When the pattern is consistent, the angle measurement effect is better when the offset angle is half of the half power beam width; Because the azimuth and dimensional patterns of the swept antenna are not completely consistent, and the half-power beam widths of the patterns of adjacent frequency points are different, it is necessary to observe whether the overlapping points of the two patterns can reach more than half of the radiation power, that is, whether they are within their respective half-power beam widths. When the frequency step is 30MHz, the intersection of adjacent patterns can be guaranteed to be within the half-power beam width of the two patterns. The frequency step is 30MHz, which is used for analysis.

Create an error value-angle table for amplitude comparison and angle measurement. The steps are as follows:

Find out the part of the angle measurement interval corresponding to two adjacent RF points in the antenna pattern.

Based on the beam pointing difference of adjacent frequency patterns, the angle measurement interval adopted in this paper is: the intersection extends from left to right by 2, and the interval length is 4.

Sum-difference mode

The error value-angle curve is obtained from the difference sum ratio, that is, the angle identification curve.

Save the angle error values obtained from all adjacent patterns, which can be used to look up a table from the measured values to obtain the target angle. This is the look-up table method. The target angle can also be obtained from the error signal by fitting.