Aperture weighting for maximum contrast of SAR imagery

An aperture weighting algorithm, amplitude contrast enhancement (ACE), has been developed for synthetic aperture radar (SAR). ACE uses an iterative, gradient-based optimization algorithm to determine the aperture weighting function that maximizes the contrast of a given SAR image. In addition to sidelobe control and apodization applications, we demonstrate that the algorithm corrects for distortions in the amplitude weighting across the phase history of a SAR data set. Furthermore, ACE mitigates the effects of corrupted or missing phase history data. Although the algorithm is inherently nonparametric, we also develop, as a special case, a parametric version, which allows for an especially efficient implementation for the raised cosine weighting function. Finally, it is possible to combine ACE with the autofocus algorithm PACE (phase adjustment by contrast enhancement) in a manner that requires essentially the same amount of computation as either algorithm alone.