Focusing resonance signatures in ultra-wideband SAR images by allpass filtering

This correspondence shows that resonance signatures in ultra-wideband synthetic aperture radar (SAR) images, which are smeared out due to their late arrival time, can be focused and extracted by postfiltering the SAR images with special two-dimensional (2-D) allpass filters. A design algorithm for FIR approximations to the desired allpass filters based on radial slice approximations (RSA) is presented.