Ground antenna phase behavior in a differential phase measuring system

A tracking system which measures distance by comparing the phase of signals arriving at a pair of spaced receiving antennas from a common source remains accurate when the signals have undergone identical phase distortions. The receiving antennas of such a system are normally mounted on a large ground plane to minimize multipath reflection errors at low elevation angles. This paper describes a study made of the effect of ground constants and ground plane size on the amplitude and phase of the electric field above a ground plane surrounded by lossy dielectric. Rapid phase shift near glancing incidence is found to be a function of elevation angle, ground reflection coefficient, and ground plane size. Results may be used to estimate tracking error in a differential phase measuring system.