Signal Propagation Modeling Based on Weighting Coefficients Method in Underground Tunnels

─ The propagation of electromagnetic waves guided in tunnels and mines is an area of scientific study which is hard to model due to multiple reflections on walls and surrounding obstacles. A novel propagation model for underground tunnels based on the weighting sum of the log-distance propagation model, the modified waveguide model and, the far zone propagation model for the ultra-high frequency (UHF) band is proposed in this paper. The propagation model is divided into five regions based on the distance between the transmitter and the receiver. Each region shows a different propagation characteristic and modeled with weighting sum of the base propagation models. Our model was tested in a tunnel with 2 m x 1.5 m cross-section and 250 m length. Measurement results are consistent with the proposed propagation model. Index Terms ─ Propagation modeling, underground tunnel, underground communications.