A new ship detection method for othr under multi-mode propagation

Multi-mode propagation usually happens in Skywave over-the-horizon radar (OTHR) due to the Multi-layer physical structure of the ionosphere, resulting in sea clutter spectrum being broadened, which seriously affects the performance of ship targets detection for OTHR. Existing methods for solving multi-mode propagation work badly in the condition of the ionosphere nonlinear disturbance or short coherent integration time (CIT) because of inaccuracy of parameters estimation. Basing on 2-D arrays adaptive beamforming, this paper studies a new ship detection method for OTHR under multi-mode propagation. Firstly, the basic principles of multi-mode propagation for OTHR and the influences on ship detection are elaborated, and the performance deficiencies of existing solutions are analysed; Secondly, OTHR echoes model under multi-mode propagation is established, and a robust adaptive beamforming method is proposed according to echoes characteristics; Finally the experimental simulations are given, simulation results verify the effectiveness of the proposed algorithm.