An N2logN back-projection algorithm for SAR image formation

We propose a fast algorithm for far-field SAR imaging based on a new fast back-projection algorithm developed for tomography. We also modify the algorithm for the near-field scenario. The fast back-projection algorithm for SAR has a computational complexity O(N/sup 2/logN). Compared to traditional FFT-based methods, our new algorithm has potential advantages: the new algorithm does not need frequency-domain interpolation, which becomes complex for the wide-angle case; the new approach is applicable to the near-field scenario, taking into account wavefront curvature; and the back-projection algorithm can be easily adapted to parallel computing architectures. For some scenarios of interest, the computational cost of the new back-projection approach is similar to or less than that for FFT based algorithms.