Adaptive beam-domain processing for space-based radars

This paper discusses beam-domain space-time adaptive processing (STAP) algorithms for a low-Earth-orbit (LEO) space-based radar (SBR). The performance of the subarray-based joint-domain-localized (JDL) algorithm is first examined for various processor parameters. Then, a combined beam-domain STAP algorithm approach that combines JDL with difference (Δ) beams is presented. It is shown that the combined JDL-Δ algorithms offer less system complexity and yield performance similar to that of JDL that uses higher degrees of freedom. It is also shown that the Earth´s rotation induces a crab angle to the platform, which makes the clutter range-Doppler spectrum vary with range. Illustrative examples show that this crab angle severely degrades the signal-to-interference-plus-noise ratio (SINR), thereby reducing the minimum detectable velocity (MDV) of STAP systems.