Maximum-likelihood receiver for low-angle tracking radar. I - The symmetric case

A new maximum-likelihood processor is described for estimating the elevation angle of a target in the combined presence of specular multipath and receiver noise, as encountered in a low-angle tracking-radar environment. The processor makes special use of the symmetry of the incident direct and specular multipath components with respect to the normal to the receiving array. The theory of the processor is supported by both computer simulation and experimental results. The effect of deviation from perfect symmetry is also examined.