Determination of antenna specification and positioning for efficient railway communication in tunnels of arbitrary cross section

This paper presents the application of the modal theory for determining antenna positioning in the railway environment. An original technique based on the Transmission Line Matrix method (TLM) for the analysis of guided structures is used to model propagation in arbitrary-shaped tunnels. Wave propagation in a rectangular tunnel with lossy dielectric walls is then studied and optimum field specifications in terms of optimum electric or magnetic field and best position for exciting the structure show that this algorithm is suitable for obtaining antenna field specifications in tunnels at high frequencies.