A Novel Method to Eliminate Ionospheric Phase Contamination in OTHR Systems

In over-the-horizon radar (OTHR), radar signals are subjected to ionosphere perturbation as they propagate through the ionosphere, and the weak echo signal from the low-speed target is almost masked by the spreading of Bragg peak. In order to acquire the spread sea clutter accurately, sliding window band-pass filters is proposed to extract the first order clutter (calibration signal), which can realize adaptive selection of the filter bandwidth. At the same time, a novel algorithm named Covariance Matrix Solving method (CMS) is presented to correct ionospheric phase contamination. Theoretical analysis and real data processing indicate that CMS method has a good performance and can obtain a better correction effect than Phase Gradient Autofocus (PGA) method.