Improved Communications in Underground Mines Using Reconfigurable Antennas

Fixed performing antennas are ineffective in providing optimum performance in a changing multipath environment, such as underground mines where channel conditions quickly change as the antenna is moved. Hence, we investigated the performance of a pattern reconfigurable antenna (RA) in improving the wireless communications link in a hard rock underground mine. An RA and a dipole were characterized and compared in line-of-sight (LOS) and nonline-of-sight (NLOS) propagation scenarios. As a proof of concept, experiments were performed at the University of Queensland Experimental Mine using a 1 GHz frequency band centered at 2.45 GHz. Analysis of complex channel impulses captured through the frequency-domain channel sounding is presented. Also, the results show that reconfigurability in the rich multipath environment achieves a 20% and 34% improvement in path loss and delay spread, respectively, compared to a fixed-beam antenna in NLOS propagation. Furthermore, more than 34% improvement in coherence bandwidth is observed in LOS and NLOS. Therefore, reliable high-data-rate communication is achievable in underground mines by the effective management of multipath effects using the RA.