An improved autofocus approach based on 2-D inverse filtering for airborne spotlight SAR

For airborne spotlight mode synthetic aperture radar (SAR) autofocusing, the residual range cell migration (RRCM) results in performance degradation. An improved inverse filtering (IF) autofocus approach based on the isolated strong point target is proposed in this paper. The new approach can simultaneously compensate both azimuth phase error and the two dimensional coupling phase error caused by the residual range migration. Therefor the bad effect caused by RRCM on autofocusing is eliminated, and the performance of inverse filtering autofocus algorithm is improved obviously. The results of real-measured data processing validate the effectiveness of the proposed method.