A Novel ISAR Imaging Algorithm for Nonuniformly Rotating Target

High resolution inverse synthetic aperture radar (ISAR) imaging of nonuniform rotating target is a challenging task because of migration through range cells (MTRC) and high order phase term. A novel ISAR imaging algorithm is proposed: (1) range compression and translational motion compensation; (2) MTRC compensation by using keystone transform; (3) the optimal order estimation; (4) fractional Fourier transform (FrFT). The proposed algorithm need not search, which reduces the computational cost. Experiment results by using MIG-25 and B-727 data have shown that the processing scheme can effectively mitigate MTRC and phase error, and it can produce well-focused images.