LINE-OF-SIGHT EM PROPAGATION EXPERIMENT AT 10.25GHZ IN THE TROPICAL OCEAN EVAPORATION DUCT

An experimental investigation into anomalous propagation of microwave emissions transmitted from a low altitude in a tropical maritime envir onment is described, The measured amplitude values are compared with p redicted values which were obtained by solving the parabolic equation. Knowledge of the refractive index profile, necessary for the paraboli c equation formulation is obtained simultaneously from measurements of pressure, temperature and humidity taken on board a spar buoy located along the propagation path. Results show large variations in signal s trength depending on the atmospheric conditions. In the absence of str ong turbulence or precipitation, general agreement between the measure d and predicted readings are observed.