Characteristic of EM-wave anomalous propagation in marine evaporation duct

Based on the atmospheric modified refractivity, the difference between the evaporation duct and the standard atmosphere is analyzed. The propagation path and the transmission loss of the EM waves are calculated respectively by ray-tracing technique and Fourier split-step method of the parabolic equation in standard atmosphere and evaporation duct. The simulation results show that evaporation duct can trap some radio rays to extend the propagation distance of EM wave and result in the appearance of radar blind zone. The characteristic of the EM wave anomalous propagation in marine evaporation duct can help to improve the radar over-the-horizon detection performance.