Fast Alignment Algorithm for Autocalibration in Digital Monopulse Radars

Calibration is important for digital monopulse radars since the target tracking performance would be degraded by the amplitude and phase imbalance among channels. However, the alignment between the radar to be calibrated and the test probe is a challenge, especially for antennas with high gain and narrow beamwidth. In this letter, we propose a fast alignment algorithm for the autocalibration of digital monopulse radars using the gradient ascent method based on the tentative radiation pattern gradient model. We verify the feasibility and the high efficiency of the proposed algorithm by simulations and an experiment of a W-band digital monopulse radar. The elapsed time of the proposed algorithm is 0.01${\bf \%}$ of the existing method and requires lower equipment complexity compared with the scanning-based method.