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.