A two-step method to Process Bistatic SAR Data in the General Configuration

This paper describes a two-step processing procedure which has a capacity of processing bistatic Synthetic Aperture Radar (BSAR) data in the general configuration based on the extended Loffeld's Bistatic Formula (LBF). For LBF, in any configuration, equal contributions to the total azimuth Doppler spectrum are assumed, which results in the failure of LBF in the high bistatic grade configurations (e.g. spaceborne/airborne configuration and highly different squint configuration). In this paper, we consider the different contributions of transmitter and receiver to the total Doppler spectrum to extend LBF. To illustrate the character of bistatic SAR signal, the two-dimension linearization operation is used to project the quasi-monstatic (QM) and bistatic deformation (BD) terms into the 2-dimensional space (slant range and azimuth time) domain. After the linearization, it can be seen that the bistatic point target reference spectrum (BPTRS) is linearly dependent on the two-dimension space variables. The azimuth-dependent phenomenon is an intrinsic feature of bistatic SAR in the general configuration. To address the two-dimension space-dependent problem, we use the two processing procedures: one is range processing which will remove the dependency of BPTRS on the range space variable, another is azimuth processing which will eliminate the dependency of BPTRS on the azimuth time variable. For the range processing, we prefer the well-known range-Doppler algorithm to cancel the dependency (i.e. RCM). For the azimuth, an additional interpolation operation is required to remove the dependency.