Research on Omega-K type algorithms for bistatic SAR

The bistatic Omega-K algorithm applying to the translational invariant (TI) configuration is discussed. The main difficulty in modifying monostatic Omega-K algorithm to handle the azimuth-invariant bistatic configuration lies in finding a solution for the 2-D target spectrum with linear property that was showed in the monostatic case. A derivation of the 2-D point target spectrum is proposed. The method described makes use of spatial variable transformation, the principle of stationary phase and phase linear approximation. The FGAN version and the ONERA version of bistatic Omega-K algorithm can be regard as different approaches to the procedure. The FGAN version adopts nonlinear transformation of the coordinates of the targets and the fitting by a straight line, while the ONERA version uses a physical reference and Taylor expansions. Both two versions make use of numerical method to solve to the stationary point problem, but the ONERA version involves more analytical elements thus allowing a convenient implementation. Moreover, we presented new expression of the semi-bistatic distance- difference in general TI configuration, and provided simulation results to demonstrate the performance of the approach in the cases of equal and unequal R/T platform altitudes.