Modified stepped-frequency SAR imaging algorithm with frequency-domain spectrum reconstruction

Stepped-frequency synthetic aperture radar (SAR) always transmits stepped-frequency chirps and reconstructs the wideband spectrum in frequency domain to achieve high range resolution. “Imaging for each sub-band, and then spectrum reconstruction” is an acceptable algorithm flow, but it has the drawback of range spectrum aliasing due to the range and azimuth (2D) spectrum twisting. In this paper, through the study of the extended range spectrum, a modified stepped-frequency SAR imaging algorithm is proposed. It solves the range spectrum aliasing by the range spectral-length extension (RSLE). Simulations and experimental results are provided to demonstrate the proposed algorithm.