Cross Range Smear Characterization in Xpatch ISAR Images

This thesis investigates a cross range smear phenomenon seen in far field, frequency domain Xpatch calculations. The phenomenon is very subtle, manifesting itself in 2-D ISAR images as a low-level scatterer response smeared in the cross range direction. This cross range smear occurs only using complex target models with certain characteristics. It is also a mathematical construct, not occurring in physical SAR systems. Using a carefully constructed scattering target set, Xpatch-generated ISAR images are used to characterize cross range smear in terms of its input parameters. The characterization is done as a DOE- based polynomial approximation to the observed smear levels. Frequency extent and bandwidth have the highest effect on cross range smear, consistently increasing smear with parameter value. Ray density is slightly less important, having primarily squared and second order influence. The choice of diffraction and first bounce algorithm has very little effect on cross range smear. In addition, the performance of a proposed smear reduction technique is analyzed against Xpatch-generated ISAR images. The algorithm generally reduces smear, but the smear reduction magnitude is not a linear function of smear value.Air Force Inst of Tech Wright-Patterson AFB OH School of Engineering and Management is the author of 'Cross Range Smear Characterization in Xpatch ISAR Images', published 2004 under ISBN 9781423516569 and ISBN 1423516567.