High-Frequency Hybrid Sky-Surface Wave Radar Target Detection Based on Time Reversal in sea Clutter Background

In this article, we propose a target detection method for high-frequency hybrid sky-surface wave radar (HF HSSWR) based on time reversal (TR), aiming to address the challenges of detecting moving ship targets in environments with ionospheric multipath and broadened sea clutter. We first establish the conventional (CO) signal model and the TR signal model based on the detection mechanism of HSSWR, considering the nonstationary channel changes caused by the time-varying characteristics of the ionosphere and the Doppler shift resulting from target movement. Then, according to the two-step generalized likelihood ratio test criterion, we derive the conventional GLRT (CO-GLRT) detector and the time reversal GLRT (TR-GLRT) detector. The two proposed detectors exhibit constant false alarm rate (CFAR) properties relative to the clutter covariance matrix. In addition, we derived closed-form expressions for the detection probabilities of both TR-GLRT and CO-GLRT detectors, and analyzed the detection performance of the proposed detectors using normalized J-divergence. The performance evaluation through numerical simulations and measured data verifies the superiority and effectiveness of TR for HSSWR.