A modified range migration algorithm for airborne squint-mode spotlight SAR imaging

Due to the reference signal based on the fixed reference range is used in the range migration (RM) algorithm, the RM algorithm is not available to process an airborne squint-mode spotlight synthetic aperture radar (SAR) data. Thus, a modified RM algorithm is developed, which can be applied on processing large scene squinted-mode spotlight SAR data without division. Based on the squint-mode spotlight SAR imaging geometry, the modified reference signal is used to dechirp the received signal. Then, using the principle of stationary phase, the presented formulation of the modified RM algorithm is analyzed. Finally, the effectiveness of the proposed method is demonstrated by some numerical simulations via a squint-mode spotlight SAR simulator.