Modeling and Processing of Two-Dimensional Spatial-Variant Geosynchronous SAR Data

Imaging of spatial-variant geosynchronous synthetic aperture radar (GEO SAR) in the L band with long integration time is discussed. To compensate for spatial variances in both range and azimuth directions, a new algorithm based on improved omega-K (ωK) and three-time azimuth chirp scaling (3ACS) is proposed. First, the integration time and the slant range model were analyzed. Second, the two-dimensional (2-D) spectrum was used for range cell migration correction (RCMC), secondary range compression (SRC), and azimuth compression, and the influences of spatial variances on each term were considered. Third, the improved ωK was used to compensate for the range variance, and 3ACS was used to compensate for the azimuth variance. The scope of 2-D focusing in high-resolution GEO SAR imaging was clearly enlarged. Finally, the performance of the algorithm was demonstrated using simulations based on a spaceborne radar advance simulator (SBRAS).