Impact of low marine atmospheric refractivity profiles on GPS signals' propagation

Atmospheric duct is an abnormal refraction mechanism in marine atmospheric environment, which may influence the propagation of utralshort waves and microwaves significantly. In this paper, the propagation characteristics of low-elevation Global Positioning System (GPS) signals under different troposphere environment are calculated using the parabolic equation method. The results show that the propagation of GPS signals in atmospheric duct conditions is obviously different with that of standard atmosphere condition, and the propagation power is more. The propagation characteristics of GPS signals in condition of horizontal-inhomogeneous-evaporation-duct are firstly studied, it is concluded that the propagation of GPS signals will be more complex due to the horizontal inhomogeneity of the evaporation duct, and the propagation loss may be up to tens of dB.