Dielectric-Covered Ground Reflectors in GPS Multipath Reception—Theory and Measurement

Global Positioning System receivers sometimes operate under severe multipath conditions, including those which include a ground specularly reflected signal along with a direct signal. Here, such a case is discussed which involves a dielectric-covered flat ground reflector, with incident energy at 1.57542-GHz right-hand circularly polarized at elevation angles between 5deg and 50deg. The relative received powers produced by the sum of the specularly reflected and direct signals are computed from conventional theory and are measured for various thicknesses of dielectrics. Both theory and measurement show that the received powers produced by the sum of the specularly reflected and direct signals have the same behavior throughout a range of elevation angles. A snow case study shows potential for inferring snow depth by fitting the theory to the measurements.