Theory of Two-Dimensional Signature Morphology for Arbitrarily Moving Surface Targets in Squinted Spotlight Synthetic Aperture Radar

This paper develops analytic equations for predicting the smear signature morphology due to surface targets having arbitrary motion within squinted spotlight synthetic aperture radar (SAR) imagery. A power-series expansion of the subaperture phase history data is applied to compute a generic expression for the down-range and cross-range components of the predicted central 2-D contour of mover signatures, including the cross-range offset. In addition, the current analysis generates an analytic approximation for the 2-D impulse response (IPR) of surface moving target signatures within subaperture images. This investigation reveals that the summation of a large number of nonoverlapping IPRs yields an excellent reproduction of the target signature, including smear width and self-interference effects, as compared with standard image formation using simulated radar data. Thus, the analytics derived herein can provide an effective methodology for understanding the shape, extent, location, width, and interference effects of smears due to arbitrarily moving surface targets for squinted spotlight SAR.