Integration of High-Order Migration Compensation and ISAR Imaging Based on KT and PSO in the THz Band

With the number of satellites increasing, it is crucial to achieve high-resolution imaging of space targets through terahertz (THz) radar. Compared with the microwave band, the THz radar with carrier frequency of 0.1–10 THz has advantages of larger bandwidth and shorter wavelength. However, even small angle rotation of large-size space target would cause severe range cell migration (RCM) in THz band. Moreover, high-order RCM is non-ignorable in THz Inverse Synthetic Aperture Radar (ISAR) imaging, which means that the direct Keystone Transform (KT) is ineffective. Meanwhile, the spatial-variant (SV) phase error contains unknown rotation velocity and range center deviation (RCD). Consequently, the estimation method based on Particle Swarm Optimization (PSO) under Max Contrast Criterion (MCC) is proposed. To correct the high-order RCM, a high-resolution imaging algorithm based on KT and Fast Gaussian Gridding Nonuniform Fast Fourier Transform (FGG NUFFT) is presented. The simulation results verify the correctness and effectiveness of proposed algorithm.