A new subaperture chirp scaling algorithm for spaceborne spotlight SAR data focusing

In order to overcome the azimuth spectrum folding occurrence in the spotlight imaging mode of the high resolution spaceborne Synthetic Aperture Radar (SAR), we presented a new extended subaperture chirp scaling algorithm (CSA) in this paper. Several phase functions of the extended CSA were modified according to the properties of subaperture processing. These modifications make the new algorithm realize the precise recombination of the phase history data of each subaperture without any additional computation load, making the subaperture overlapping and azimuth time extension unnecessary. The validity of this new algorithm is proved through point target simulations by adopting TerraSAR-Xsystem parameters in the spotlight mode with 1m resolution and a swath of 10 Km both in the range and azimuth.