Improving SAR images: Built-in geometric and multi-look radiometric corrections

SAR systems installed on small aircrafts and UAVs suffer from trajectory deviations and instabilities of antenna orientation. These kinds of motion errors lead to significant geometric distortions and radiometric errors in SAR images. In the paper, we describe a time-domain multi-look stripmap SAR processing algorithm with built-in geometric and multi-look radiometric corrections. Geometric correction is performed due to azimuth reference functions and range migration curves specially designed to produce SAR images directly on a rectangular grid on the ground plane. Radiometric correction is based on multi-look processing with extended number of looks. The proposed techniques have been successfully tested with a Ku-band SAR system installed on a light-weight aircraft.