Some aspects of design and environmental management in HF surface wave radar

With the current emphasis on the surveillance of coastal waters, particularly for economic exclusion zone (EEZ) applications, there has been an increased interest in the capability of HF surface wave radar (HFSWR) to detect targets beyond the conventional radar horizon. The surface wave mode is generated where a vertically polarised high frequency electromagnetic wave is launched over a saline water surface; this then behaves in a manner such that there is significant propagation of the field around the curvature of the Earth. As this propagation mode relies on the surface currents in the conducting media of the sea, the resulting additional propagation loss has a dependence on the water salinity, surface roughness and frequency. A comparison of two-way HFSW loss with frequency over a smooth surface is shown. As the operating frequency increases, the additional propagation losses increase; however many other system constraints ease as the wavelength grows smaller (e.g. antenna size and target Doppler shift). This paper highlighted and provided some analysis for the frequency management and impulse suppression techniques that should be implemented in an effective HFSWR.