Modelling and Data Analysis of 50 to 5000 kHz Radio Wave Propagation in Coal Mines. Technical Services for Mine Communications Research

摘要

The objective of this work was to formulate simple theoretical models characterizing medium frequency (MF) radio wave propagation in underground room-and-pillar coal mines to predict the most favorable operating frequencies and maximum communication ranges for portable radios carried by key miners. This was achieved and confirmed experimentally for conductor-free areas of coal mines. In areas where a conductor such as a power cable is present, applicable data must yet be taken before the propagation model can be confirmed. This report describes the theoretical models developed for MF radio propagation in coal mines, compares theoretical results with experimental measurements made in a large number of mines located in various coal seams, and summarizes the findings and their implications for portable radio communications between roving miners.