An Auto-Focus Algorithm for Missile-Borne SAR

Compared with an air-borne SAR, a missile-borne SAR has three important characteristics including a high flight speed, a straight movement with non-constant velocity and a large squint angle. In several SAR imaging algorithms of spotlight mode, approximately compensating of range migratory results to bad imaging. In this paper, according to the imaging characteristics of missile-borne spotlight SAR for a ground target, we use the phase gradient algorithm to carry out the phase error correction. This new approach can improve the image quality obviously and make the auto-focus processing converge better. The simulation results show the validity of the proposed method.