An Imaging Algorithm for High-Squint SAR with Accelerated Trajectory Based on Spectral Regularization and Spectral Fusion

High-squint synthetic aperture radar (SAR) imaging with accelerated trajectory is significant for target detection and precise guidance. However, seriously space-variant Doppler parameters caused by high-squint angle and acceleration challenges the imaging performance. This paper proposes a precise imaging algorithm for high-squint SAR with accelerated trajectory. At first, coarse sub-image and sub-spectrum are obtained by factorized back-projection (BP) kernel in sub-aperture. Secondly, precise sub-spectrum center and spectrum width are derived corresponding to high-squint angle and acceleration, which are different from traditional imaging model. In the next, the sub-spectrum is corrected and regularized to avoid folding, and fused to generate whole aperture spectrum. Finally, the whole aperture spectrum is transformed into time-domain to obtain focused image. Simulated and measured SAR data experiments validate the proposed method.