Focusing of SAR With Curved Trajectory Based on Improved Hyperbolic Range Equation

For a synthetic aperture radar (SAR) system with curved trajectory, which is different from the conventional SAR, the downward velocity and the acceleration result in highly complicated range history, making it hard to achieve a focused target response. The traditional SAR imaging algorithms are not accurate enough to compensate the phase errors introduced from the highly complicated range history. In this letter, considering the impact of complex range history, an improved hyperbolic range equation is proposed to access the 2-D spectrum for curved trajectory SAR imaging. Based on the derived spectrum, frequency-domain imaging algorithm can be performed to focus targets. By analyzing the phase error and comparing with other current range models, the proposed range model is proved to be precise enough to deal with the complex motion model happened in curved trajectory SAR imaging. Simulation experiments are implemented to evaluate the imaging performance of the proposed approach.