Effect of flat surface assumption on time-domain imaging of rolling terrain for one-stationary bistatic UWB SAR

During normal synthetic aperture radar (SAR) processing, the flat earth´s surface is usually assumed when performing time-domain imaging. However, this assumption induces the geometric error in imaging, thereby influencing the focusing quality. The effect of this assumption on time-domain imaging of rolling terrain for one-stationary bistatic UWB SAR is examined in this study. Based on the imaging analysis of the linear flight geometry case, it is found that this assumption will lead to some problems of the focusing position offset and target defocusing. For the nonlinear flight geometry case, it has the same focusing position offset, but has more serious target defocusing. The expression of the focusing position offset and the quantitative restriction on focusing the target are derived in detail. The correctness of the theory analysis is validated by simulation SAR data processing results.