Focusing of General Bistatic SAR Configuration Data With 2-D Inverse Scaled FFT

This paper presents a bistatic focusing solution for the general case, when transmitter and receiver trajectories move along nonparallel trajectories with different velocities. The approach in this paper is based on the point target reference spectrum for an arbitrary bistatic configuration, derived from our previous publications. Based on various simulations, the validity of the formula for both airborne and spaceborne configurations is demonstrated. Focusing for special bistatic azimuth time-invariant configurations, "tandem" and "translationally invariant" constellations are accomplished. All focusing algorithms have been developed in an interactive data language and verified with adequate simulation results. The bistatic algorithm was further successfully applied to real bistatic data acquired by the German Research Establishment for Applied Natural Sciences\´ PAMIR and AER-II synthetic aperture radar systems. Processing in the general case turns out to be additionally truly azimuth time variant. It is solved by implementing a novel two-dimensional inverse-scaled fast Fourier transform algorithm