Multipath Limitations on Low-Angle Radar Tracking

This paper investigates the problem of tracking targets at a low elevation angle in the presence of specular and diffuse multipath. Quantitative estimates are derived of the elevation angles, and hence, range, at which targets of specified height can be accurately tracked. A parametric approach is followed in which the long-standing uncertainty of how terrain forward-scatters at low grazing angles is recognized at the outset. Particular attention is given to the effects of target motion which permit rejection of multipath components falling outside the radar tracker´s passband. The results are presented in a form which can be readily applied to a spectrum of radar trackers with differing requirements. The limited experimental ental data on the specular and diffuse scattering parameters for several generic types of terrain are applied to estimate the significance of multipath under different situations and to indicate specific areas in which additional experimental data are critically needed.