Bistatic SAR - translational invariant processing and experimental results

Bistatic synthetic aperture radar (SAR) uses a separated transmitter and receiver, flying on different platforms, which enables the exploitation of additional information contained in the bistatic reflectivity of targets. The feasibility of the bistatic concept has already been demonstrated although technical problems such as the synchronisation of the oscillators still persist. The processing of bistatic raw data has still not been resolved sufficiently, either. The omega-k (or range migration) processor has proven popular in the monostatic case because of its relatively simple implementation, its close-to-optimum performance and its numerical efficiency, but has not been generalised for the bistatic case. A method to eliminate the deviation of the bistatic range history from the monostatic hyperbolic shape in the omega-k domain making subsequent omega-k processing possible has been recently proposed, and generalisations of the omega-k algorithm to the bistatic case can also be found. Adding to the literature, an omega-k-type processor for the special case of equal-velocity vectors of transmitter and receiver, the so-called 'spatial invariant' case, is introduced. This processor is not optimum in the sense of the monostatic omega-k processor but degradation for wide ranges of geometrical parameters proved negligible. During flight testing in November 2003, different spatially invariant flight geometries were tested and high resolution bistatic SAR images were generated successfully.