Autofocusing and residual migration of SAR images

A particular approach to the azimuth migration of synthetic aperture radar (SAR) data is discussed. It is shown that a slightly defocused SAR image can be corrected by means of a short monodimensional filter with a quadratic phase vs. time characteristic. This kind of processing, called residual migration, has reduced computational complexity and minimal storage requirements compared to conventional focusing techniques. Residual migration is therefore suitable for implementing an efficient SAR autofocusing processor, which usually requires several focusing iterations to get a good image quality