An approach to correction of ionospheric phase contamination in HF skywave radar systems

In high frequency (HF) skywave over-the-horizon radar (OTHR), radar signals are subjected to phase contamination as they propagate through the ionosphere, leading to severe degradation capability of OTHR radar, so that it needs to be corrected. According to the high spatial correlativity of the ionosphere contamination and the adjacent range cells are subjected to the same contamination, a new approach is applied to the ionosphere decontamination of OTHR echoes based on maximum likelihood estimation auto-focus method in ISAR and clutter suppression. The decontamination procedure is divided into two steps: firstly eigenvector projection is used to preprocess signals, and secondly using maximum likelihood estimation method to estimate contamination. The simulation and real data processing results show that the method is of effectiveness and robust performance on different kinds of ionospheric phase contaminations.