Depolarization Due to Wedge Diffraction in Satellite Radiowave Communication

In this paper, the depolarization effect due to the electromagnetic wave diffraction from the rooftop wedge of a building at 1.575 GHz frequency is presented. Diffraction measurement was performed using a dual circularly polarized (CP) antenna system. The Right Hand Circularly Polarized (RHCP) Global Positioning System (GPS) satellite transmission was utilized for measurement. The orbital motion of a single satellite enabled diffraction measurement as a function of the receiver depth in the shadow region, while the receiver was static. The experimental result of RHCP signal was compared with a theoretical knife-edge diffraction model, and they were in good agreement. In case of the deep shadow region, we found the levels of left- and right circular polarized signals to be equal, which indicates a strong depolarization of the incident RHCP wave. The observed depolarization for conductive wedge is explained by the geometrical theory of diffraction.