An Improved Method for Antenna and Probe Alignment in Auto-calibration of Millimeter-Wave Digital Monopulse Radar

Calibration is an effective method for improving digital monopulse radar tracking performance since it can eliminate the amplitude-phase imbalance between channels. Fast and accurate alignment between the antenna under test and the probe is an important part of the calibration. however, the narrow beam and high gain of a millimetre-wave band antenna pose a challenge to the alignment. To tackle this problem, we propose an improved alignment method based on the gradient feature of the radar radiation pattern. The method incorporates adaptive moment estimation to resist noise in the iteration process of the alignment. The high-accuracy alignment of the proposed method is verified by simulation and experiment. The root mean squared error of the alignment of the proposed method is 0.0046 degree in the absence of noise. At the SNR of 30 dB, the root mean squared error of the alignment is 0.008 degree. The proposed method improves the calibration efficiency and thus has a broad application prospect.