Refined extended chirp scaling algorithm for spaceborne ScanSAR imaging

To resolve the precise imaging problem of spaceborne ScanSAR with large range cell migration, a novel Refined Extended Chirp Scaling (RECS) algorithm is proposed. The algorithm is based on both Chirp Scaling algorithm and SPECAN algorithm, which could finish the precise imaging with much lower time complexity. In this paper, the full derivation and the realizing approach of the algorithm are presented with the squinted equivalent range model, which describes the relationship of spaceborne ScanSAR geometrical more precisely than the broadside range model. And the optimum look weighting approach is also introduced to avoid the scalloping effect. Finally, the algorithm is verified by simulations.