An algorithm is introduced which corrects for problems which arise in spotlight-mode synthetic aperture radar (SAR) when a significant amount of wavefront curvature is present. Wavefront curvature can be problematic when it is desired to reconstruct high-resolution images of ground patches which subtend a large angle at the radar. The proposed, non-Fourier, algorithm uses mappings to modify the convolution-backprojection method of computed tomography, providing reconstructions from circular-arc projections that are of the same high quality as those made from standard straight-line projections using the unmodified algorithm. In addition, other problems in high-resolution SAR imaging are identified which have solutions involving tomographic concepts, including situations which give rise to fan-beam-like projections. The new algorithm can be modified to deal with these problems as well.
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