Modeling and Measurement of Radio Propagation in Tunnel Environments.

A simple radio frequency (RF) testing system that can be conveniently built and used for measuring radio propagation in tunnels is introduced. With the proposed testing system, RF power attenuation with distance in a train tunnel was measured at four frequencies (455, 915, 2450, and 5800 MHz) for both horizontal and vertical polarizations. Two analytical modeling methods-the ray tracing and modal methods-are applied to model RF propagation in the tunnel. The theoretical predictions based on both methods are compared to field measurements and find good agreement.