Experimental study on fading characteristics in the evaporation duct propagation at C band

The evaporation duct is an important anomalous transhorizon propagation mechanism in marine areas. It has important effects on the design and operation of marine radio system. Based on the experimental data of C-band microwave transhorizon propagation in evaporation duct environment in the South China Sea, the characteristics of path loss and fast signal fading distribution at different propagation distances are compared and analyzed. The experimental results show that with the increase of propagation distance, the propagation loss gradually approaches the tropospheric scattering propagation loss, and the main propagation mechanism gradually transits from evaporation duct to tropospheric scattering. The fast fading distribution of the received signal level sampled in 5 minutes is close to the generalized Rayleigh distribution, and the fading depth and amplitude are smaller than the Rayleigh distribution. The results are valuable for the design of over-the-horizon communication system using evaporation duct.