Analytic System Models for Ultra - WidebandWide - Angle Low Frequency SAR and NewPostprocessing Techniques

The latest generation of fully polarimetric, ultra wideband, wide angle, low frequency, foliage and ground penetrating synthetic aperture radars presents many new challenges for signal processing. Huge amounts of data need to be processed to focus high quality images. At the same time only a few small subimages contain important information. We investigate the relationship between the focused image and the reeec-tivity proole and show that a linear shift-invariant model adequately represents the overall process when the focusing is done with a backprojection algorithm over a constant integration angle. We extend this result to other focusing algorithms. The derived signal model can be used to implement many computa-tionally expensive processing techniques, previously done on the raw data, as equivalent postprocessing algorithms which can be applied selectively to subimages.