Some new aspects on low-elevation radar coverage

A detailed overview on all points which influence the radar coverage of low-flying targets is given. Earth curvature and terrain, wave-propagation effects like refraction, diffraction and reflection with multipath, disturbances like clutter and neighboring transmissions, antenna beamwidth and tilt are considered likewise for detection and tracking purposes. All these influences essentially depend on the target range, on the radar and the target height, some on the azimuth direction, on the radar frequency and on the available energy. Neither simple line-of-sight calculations based on terrain maps only nor simple wave-propagation models yield adequate general statements on the radar coverage. It is shown, how the most essentially contributing effects can be extracted on the basis of effective heights and how the moderate use of statistical methods can lead to a realistic estimate of the coverage in a medium Central Europe terrain for a special radar. Additional considerations arising with disturbances, radar netting and multistatic configurations are touched finally.