Back-Projection Algorithm Characteristic Analysis in Forward-Looking Bistatic SAR

The transmitter and receiver trajectories are extremely asymmetric in forward looking bistatic SAR (FL-BSAR), so it is difficult and not straightforward to apply general frequency domain imaging algorithms in FL-BSAR imaging. The back-projection algorithm is operating in the time domain, therefore it can be directly used for FL-BSAR image formation. In this paper, the error of the back-projection (BP) algorithm for FL-BSAR is analyzed in detail. The result of the error analysis is validated by applying the proposed error criterion on real data. Moreover, under the case of FL-BSAR, the equation describing the sidelobes of the BP algorithm in the cross-range direction is derived and presented in closed form. Finally, the derived equation is verified by simulation