An advanced equivalent slant range model and image formation in geosynchronous SAR

Synthetic aperture radar on geosynchronous satellite (GEO SAR) has significant potential advantages over conventional low Earth orbit radars, albeit it also has challenges to overcome. In GEO SAR, the imaging geometry is more complicated and the range and azimuth variances are more severe. In order to deal with these problems, this paper presents an advanced equivalent slant range (AESR) model for the synthetic aperture radar undergoing an inclined circular orbit. Furthermore, the range and phase error between AESR model and conventional slant range model are also gauged in detail. Meanwhile, based on the AESR model, the accurate two dimensional (2-D) frequency spectrum (PTFS) expression of point target is obtained. And the modified algorithm and simulation results validate the AESR and show its advantages in image formation in GEO SAR cases.