Research on characteristics of first-order sea clutter for high-frequency sky-surface wave radar

In high-frequency (HF) hybrid sky-surface wave radar, the first-order sea clutter broadening is severe under the influence of the ionosphere and bistatic angle. This affects the detection of ship targets. Thereby a comprehensive analysis is essential and will be presented in this study. First, according to the geometry configuration and detection characteristics of this new system radar, the positioning principle and the range of grazing angle are analysed. Then, the first-order sea clutter Bragg frequency is presented and broadening model is given on the basis of the system configuration. Next, the mechanism of first-order sea clutter frequency shift and broadening is explained and, based on the system layout, simulation is provided to illustrate the effects of various factors on first-order sea clutter, including ionosphere, grazing angle and bistatic angle. Moreover, the characteristics of sea clutter frequency shift and broadening in different range and azimuth are analysed. Finally, the results of theoretical analysis are compared with the experimental data based on the newly-developed integrated experimental system, and the dominant factor of sea clutter broadening is studied. Simulation results show that the results of experiment are consistent with that of theoretical analysis.