Underground Radio Communication and its application for use in mine emergencies

A brief section outlines the requirements for a communication system for use in mine emergencies. Electro-magnetic radiation through the rock encountered in South African gold mines is then considered and the results of laboratory tests on borehole core samples enumerated. This work leads to the choice of a suitable operating frequency. The radio apparatus finally developed for this purpose is then briefly described and circuit diagrams are provided. A Table indicating the results of practical underground tests on this apparatus is included and significant points relating to these tests are discussed.