LAUSR

In recent years, the ground Cartesian back-projection (GCBP) algorithm has demonstrated significant advantages for bistatic forward-looking synthetic aperture radar (BFSAR) imaging with arbitrary geometries and complex configurations, primarily due to its interpolation-free operation. However, airborne BFSAR systems must additionally address motion error compensation challenges. Implementing effective motion compensation (MoCo) within the GCBP framework for BFSAR presents two key challenges: 1) the forward-looking configuration induces severe image spectrum tilt and nonsystematic range cell migration (NsRCM), significantly degrading phase error estimation accuracy and 2) spectrum resampling during BP processing obstructs direct time domain phase error (TDPE) estimation from the image. To address these challenges, this article proposes a phase error reverse recovery method based on ground combined beam coordinate (GCBC) for BFSAR. The proposed MoCo method establishes the GCBC system aligned with the echo signal’s azimuth Doppler variation, which eliminates image spectrum tilt and reduces NsRCM caused by the bistatic configuration. Within this system, we introduce the spectrum center correction and spectrum tilt correction, which effectively remove image spectrum aliasing and enable accurate image domain phase error (IDPE) estimation. Furthermore, an analytical reverse recovery relationship between IDPE and TDPE is derived. These stages significantly enhance the accuracy and robustness of BFSAR motion error estimation. Simulation and real data results demonstrate the proposed method’s superior performance.