Study on Rough Sea Surface Effects on Electromagnetic Wave Propagation in Evaporation Duct

In order to research the influence of evaporation duct on electromagnetic wave propagation,parabolic equation model has been used in the electromagnetic wave propagation prediction.Since most of correlational researches are based on the assumption of specular impedance condition,and not consider the rough sea situation caused by wind,this paper took Miller-Brown roughness reduction factor into consideration and then provided a rough sea impedance coefficient formula.Combined with the actual condition of evaporation duct in Chinese sea areas,the trapping possibility of the GPS signals was analysed and its propagation loss was calculated.The simulation results show that GPS signals can be trapped in the evaporation duct over-the-horizon transmission and the greater the wind is,the more rough the sea surface is,and the smaller the distance of the over-the-horizon transmission is.When the wind speed reaches a certain level,it can almost counteract evaporation waveguide over-the-horizon propagation phenomena.So it has great influence on the electromagnetic wave propagation in an evaporation duct.