Polarization dependence of GPS signals reflected from the ocean

The authors discuss the interpretation of a recent GPS sea-bounce data set. Raw signal data were recorded on an aircraft equipped with two down-looking antennas for receiving both LHCP and RHCP reflections from the ocean surface (as well as the standard up-looking direct-path RHCP antenna). Concurrent measurements of the local wind and wave conditions were obtained from a nearby research vessel. The reflected LHCP waveforms were similar to those reported previously. The measured RHCP waveforms were only about 10 dB below those from the LHCP antenna. As far as the authors know, detection of the (depolarized) RHCP waveform has not been previously reported, and none of the scattering models currently in use can explain the large RHCP return.