Frequency domain imaging algorithm for spaceborne/airborne hybrid bistatic SAR

A frequency domain imaging algorithm for the hybrid spaceborne/airborne BSAR is presented. The key point of deriving the algorithm is the analytical evaluation of the system point target response´s 2-D spectrum. To overcome the difficulty of resolving analytical solution for the stationary phase point, the spectrum´s phase is approximated by two-order Taylor expanding around the point, which is not only in the neighborhood of the system´s corresponding stationary phase point but also can be obtained analytically. Thus the approximated analytical spectrum is pretty close to the actual one. In the imaging algorithm, both range-dependent range cell migration and azimuth-dependent range cell migration are compensated in two steps: Inverse Scaled Fourier Transform which can be realized through the chirp z-transform and phase multiplication. The validity of the algorithm is demonstrated by experiment with the simulated data.