Analysis of path gain inside tunnels based on FDTD and ray tracing methods

Tunnel simulations are important to study the propagation mechanisms inside tunnels. In this work, FDTD and ray tracing methods are used to simulate the path gain for 2 transmitters located inside a rectangular concrete tunnel. The applicability of ray tracing is analyzed by comparing it with results from FDTD. FDTD results with and without object inside the tunnel show that at distances far from the transmitter, the path gain can be approximated with a constant attenuation.