Over-the-horizon Optical Propagation in a Maritime Environment

An experimental-theoretical program aimed at characterizing over-the-horizon (OTH) propagation via marine atmospheric aerosols is described. Pathloss measurements as a function of transmitter-receiver azimuth-elevation angles for 1.06 microm and 0.53 microm over two OTH links are reported. The first link involves an overwater range of 63 km with 19-km and 40-km horizons; the second involves an overwater range of 128 km with a 19-km horizon. Two theoretical models, one based on particulate single scatter and the other based on particulate multiple scatter, are presented and compared with the pathloss measurements obtained over the 63-km link. Good agreement between both models and experiments is shown. No quantitative comparison between the models and the 128-km experiment is made because of the lack of accurate meteorological data over this extended path.