Abstract

The transmitted Global Positioning System (GPS) signal has Right Hand Circular Polarization (RHCP) and it changes to Left Hand Circular Polarization (LHCP) after being reflected. The proportions of RHCP and LHCP power levels depend on characteristics of reflecting surface and satellite elevation angle. The change of polarization can be evaluated by comparing the measured RHCP and LHCP levels. This paper reports the results of Signal-to-Noise Ratio (SNR) data for direct and reflected GPS signal components measured over sea and land surfaces. First, field measurements with two dual polarized antennas having both RHCP and LHCP are performed in both environments. Then, SNR-based analysis is done to compare reflection levels between two reflecting surfaces. The results show that the SNR of reflected signal from seawater is on average 2 dB or more higher than that of signal reflected from asphalt or ground.