Two-dimensional Spectrum for Diving Stage SAR Processing with High-order Equivalent Range Model

For airborne synthetic aperture radar (SAR) processing in its diving stage, the diving velocity brings additional range variance to the range history in the synthetic aperture time. The traditional hyperbolic range model is not accurate enough to approximate the actual range equation and the precise two-dimensional spectrum cannot be achieved. In order to address this problem, a highly accurate spectrum deduction based on high-order equivalent range model is proposed in this paper. By introducing the high-order terms, more degrees-of-freedom are obtained for the equivalent range model and the actual range history can be accurately fitted. Based on the achieved range model, the two-dimensional spectrum for diving stage SAR can be accessed. Simulation experiments are carried out to validate the effectiveness of proposed spectrum.