Refocusing of Ground Moving Target in Circular Synthetic Aperture Radar

Due to the non-cooperative motion of ground moving targets, they appear smeared and dislocated in circular synthetic aperture radar (CSAR) imagery. Refocusing of ground moving target in CSAR is a challenging problem because of the circular trajectory of the radar platform and unknown motion parameters of ground moving targets. In this paper, an inverse SAR (ISAR) technique-based method with Legendre polynomial approximation for ground moving target refocusing in CSAR is proposed. Different from the conventional ISAR-based method, the method extracts range migration of the moving target in the range-frequency domain directly, which can avoid the range alignment procedure in conventional ISAR techniques. Furthermore, the Legendre polynomial approximation is applied to fit the extracted range migration, which can be carried out iteratively to fulfill the requirement of accuracy. The experimental CSAR data processing results show that the proposed method can achieve satisfied imaging quality of ground moving targets.