Path Loss Analysis for Array Antenna systems in Underground Mine at 3.5GHz

In this paper, path loss characteristics of the underground mine channel for a 64-element uniform rectangular array (URA) antenna system at 3.5GHz are presented and analyzed. Measurements were conducted in an underground mine environment, including both line-of-sight (LoS) and best-line-of-sight (Best-LOS) scenarios, with the transmitter-receiver (Tx-Rx) separation distance ranging from 5m to 70m. The log-distance path loss model was used to evaluate the path loss performance from the measurement data. The obtained path loss exponents were found to be 1.56 and 1.76, with shadow fading standard deviation of 1.34dB and 2.32dB for LoS and Best-LOS, respectively. These results indicate that the propagation characteristics in an underground mine have a waveguide effect on the propagated signal. As a result, the 3.5 GHz frequency band could be a suitable candidate for 5G communications in underground mine environments.