Advanced range migration algorithm for ultra‐high resolution spaceborne synthetic aperture radar

To achieve ultra‐high resolution images, processing algorithm of spaceborne synthetic aperture radar (SAR) faces significant challenges such as the curved orbit, the unneglectable propagation time and the space‐variant effective velocity. In the light of imaging requirements of the ultra‐high resolution spaceborne SAR, an advanced range migration algorithm (ARMA) is presented in this study. Firstly, a new slant range model is developed by incorporating straight orbit approximation with additional linear, cubic and quartic term. Subsequently, a two‐dimensional spectrum is derived by making use of Fourier transform pairs and the approximate azimuth stationary point based on the new range model. Finally, a novel RMA is derived. In this algorithm, the accurate range cell migration correction (RCMC) is done through two steps: the effective velocity dependence RCMC and the bulk RCMC, and the range‐variant azimuth filtering is accomplished. Simulations are carried out to verify our proposed algorithm, which indicate that ARMA can keep precise even the resolution is up to decimeter level.