Analysis and Application of RF Transmission in Electric Railway Tunnels

RF transmission in electric railway tunnels is studied based on the characteristics of the tunnel walls and the fact that there are catenary and rails as paths of signals. The RF frequency, its propagation mode and the calculation of the electric field are analyzed. As an example, application of the radio transmitters designed for communication in a mountainous section in Baoji-Chengdu railway is presented. It is shown that an electrified railway tunnel is an effective channel for transmission of language and slow digital signals.