Effect of Antenna Location on Uniformity of Radio Wave Coverage in Rectangular Tunnels with Different Cross Section Sizes

In this paper, effect of transmitting antenna location on uniformity of radio wave coverage in tunnel is studied. Radio wave coverage is modeled by ray-tracing method. A factor named system field strength flatness factor is put forward and applied to evaluate radio wave coverage properties in tunnels. The variation laws of system field strength flatness factors with antenna positions in tunnels with different cross section sizes are compared. The results show that the uniformity of radio wave coverage is sensitive to the position of transmitting antenna. Moreover, for tunnels with different cross section sizes, the antenna layouts which generate low system field strength flatness factor are different. Conclusion of this paper can provide guidance for the antenna layouts in tunnels with different cross section sizes.