VHF propagation experiment-polarization dependence of forward sea scatter near grazing incidence

In February of 1993, working at the Pacific Missile Range Facility (PMRF) in Kauai, Hawaii, Science Applications International Corporation fielded an experiment designed to measure electromagnetic propagation loss over the ocean. The objective of the experiment was to measure the effect of the ocean surface on a transmitted electromagnetic wave as function of transmission frequency (20 frequencies from 50 to 250 MHz and 2 UHF frequencies), polarization (complete scatter matrix), grazing angle (1 and 3 degrees), and height above the ocean surface (0 to 8 meters). We present the results of analysis performed on data collected at 53.2 MHz comparing propagation at horizontal and vertical polarization. At 53.2 MHz, as predicted by the Rayleigh roughness criterion, ocean roughness has no observable impact on loss at either polarization. The spectral content of the propagation loss has been demonstrated to be different for horizontal and vertical polarization suggesting a different scattering mechanism for the two polarizations as predicted by perturbation theory.