A sub-aperture and blocking autofocus backprojection method for SAR

The autofocus backprojection (BP) algorithm based on image sharpness metric has obtained excellent performance for motion error compensation. However, there are still two serious problems should be considered. Firstly, the spatial variance of motion errors is ignored, which can result in azimuth defocus for targets far away from the invisible reference target. Secondly, the use of redundant antenna phase centers (APCs) for a target leads to the excessively concentrated energy distribution along azimuth direction. In this paper, we demonstrate the strategies of range blocking and sub-aperture processing to solve the two problems, respectively. The simulation results validate the effectiveness of our methods.