Line-of-sight EM propagation experiment at 10.25 GHz in the tropical ocean evaporation duct

An experimental investigation into anomalous propagation of microwave emissions transmitted from a low altitude in a tropical maritime environment is described. The measured amplitude values are compared with predicted values which were obtained by solving the parabolic equation. Knowledge of the refractive index profile, necessary for the parabolic 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 strength depending on the atmospheric conditions. In the absence of strong turbulence or precipitation, general agreement between the measured and predicted readings are observed