Aspect Dependent Phase Error of Rotating Targets in Sar Imagery

Moving targets in a synthetic aperture radar image may appear defocused, distorted, or translated from their true position in the scene. In this study, we present an analysis of the phase errors in the frequency domain phase history data that lead to these imaging artifacts. Using spatial and temporal Taylor expansions, we derive an analytic form of the phase error for broadside collection geometries and for arbitrary target motion. We analyze the aspect dependent quadratic phase error for targets rotating about their roll, pitch, and yaw axes and use the analysis to predict a maximum size target size that may be imaged in focus. We perform simulations for both an <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$X$</tex> band SAR collecting from both airborne and spaceborne collection geometries.