Radio communication in mines

Abstract

The effect of the electrical properties of rock on the propagation of electromagnetic energy are investigated, particularly from the point of view of using laboratory determined values in predicting the attenuation characteristics of the rock medium and its variation with frequency. It is shown that the curve representing this characteristic increases with frequency as expected and exhibits higher attenuation than that predicted from laboratory sample values. The effect of a surrounding dissipative medium on antenna performance is examined, and the characteristics of the two representative elemental antenna types discussed from the point of view of their comparative effectiveness when operating within the lossy medium. The electrical properties of a small loop antem.3 are presented.