A fast back-projection algorithm based on equivalent slant range model for high-squint SAR imaging

Because back-projection algorithm (BPA) is independent of the azimuth-invariant hypothesis of the echo signal, it has significant advantages for synthetic aperture radar (SAR) imaging with arbitrary trajectory. Although Cartesian fast back-projection algorithm (CFBPA) is proposed to improve the efficiency of BPA, for high-squint SAR (HS-SAR) imaging, the geometric configuration of HS-SAR greatly enhances the space-variant property of the spectrum, which leads to the ineffectively compressed spectrum and decreases the efficiency of the sub-image merging in CFBPA processing. In this paper, an equivalent slant range model (ESRM) based on hybrid coordinate system (HCS) is proposed for HS-SAR imaging. Benefiting from the designed ESRM, the space-variant property of the wavenumber spectrum can be significantly degraded to improve performance in spectrum compression and accelerates the sub-image merging. Promising results from simulation experiments are provided to validate the high performance of the proposed algorithm.