Synthetic Aperture inversion for non-flat topography

This paper considers Synthetic Aperture Radar and other synthetic aperture imaging systems in which a backscat-tered wave is measured from positions along a single flight track. We assume that the ground topography is known but not necessarily flat. We consider two cases, corresponding to the degree of directionality of the antenna. For the high-directivity case, we propose an imaging algorithm involving backprojection and a spatially varying filter that corrects for the antenna beam pattern, source waveform, and other geometrical fac-tors. We give conditions on the relationship between the flight track and the topography to avoid artifacts. We show that the algorithm correctly reproduces certain features of the scene. For the case of an antenna with poor directionality, the image produced by the above algorithm contains artifacts. For this case, we analyze the strength of the artifacts rela-tive to the strength of the true image. The analysis of this paper shows that the artifacts can be somewhat suppressed by increasing the curvature of the flight track and by keep-ing the desired target in view for as long as possible.