Terrain impact on HF radar deployment for homeland security applications

Emerging homeland security applications require low-cost and quickly deployable HF radar systems. In order to overcome the significant costs/unavailability of land lease in coastal areas for fixed applications, deployment of HF radar systems in challenging terrain environments is necessary. One such environment is the hilltops which naturally have slope and roughness. In this paper, through the investigation of radio wave propagation in such environments, we examined the effect of the slope and roughness of the terrain on the performance of HF radars. It is shown that the slope of the terrain will affect the effective inter-element spacing of the array and causes beamforming and scanning errors. It is also shown that surface roughness of the terrain also changes the effective inter-element phase differences and hence array performance. While the effect of the slope could be very significant diffraction effects from surface roughness resulted in a much smaller error of about 18°.