Radio propagation at 900 MHz in underground coal mines

This paper reports on experimental results of radio propagation in two underground coal mines. Measurements were performed at 900 MHz on horizontal and vertical polarization in typical coal mine operational zones. Values of propagation loss in dB/100 m are derived. Additional losses due to coal mine curvatures and common coal mining equipment obstructions are also presented. A hybrid tunnel propagation model consisting of the free space propagation model and the modified waveguide propagation model is used to explain some measurement results. Based on these results, we believe that microcellular radio communications systems are feasible in coal mines.