Analysis of Radio Frequency Transmission in a Semicircular Mine Tunnel Containing Two Axial Conductors

We present an analysis of the propagation in a uniform tunnel of semicircular cross section that contains two axial conductors. In particular, we show that, even if one of these conductors has high ohmic loss, one of the two propagating modes has relatively low attenuation. This corresponds to the situation where an unloaded dedicated wire is used to improve radio frequency communication in a mine tunnel that contains a heavily loaded trolley wire.