Focusing Multistatic GEO SAR With Two Stationary Receivers Based on Spectrum Gap Alignment and Recovery

Multistatic synthetic aperture radar (SAR) composed of a geosynchronous SAR illuminator and two stationary receivers has the ability to continuously monitor areas of interest. The spatially variant azimuth wavenumber spectrum gap caused by the limited synthetic aperture time may result in a high sidelobe level, which leads to artifacts in the image. This article exploits the spatial invariance of the gap length and proposes a new imaging method to fill the spectrum gap via gap alignment and data recovery. The spectrum gaps of all the targets are aligned based on spectrum shifting, and the full spectrum is recovered using spectrum estimation. Simulation results of point targets and extended targets verify the superiority of the proposed method compared to existing algorithms.