Analysis of the Evaporation Duct Delay for Over-the-Horizon TDOA Positioning

The delay caused by rays must be evaluated effectively when using the evaporative duct to realize the over-the-horizon TDOA Positioning. Based on the ray tracing algorithm of Taylor series approximation, this paper establishes a propagation model of rays within the evaporation duct to analyze the delay caused by the multipath effect and the ray propagation speed. The results show that the evaporation duct delay is influenced by the height of the receiving antenna and the height of the duct. The multipath delay of rays that propagate over the horizon within 250 km is approximately on the order of 100 ns, and the multipath delay error is approximately on the order of 0.1 ns.