Mining Publication: Research on the Transmission of Electromagnetic Signals Between Mine Workings and the Surface
Field studies (Contract No. H0101691) of ambient electromagnetic noise and electrical transmission properties of coal mine overburdens in Colorado, Illinois, Pennsylvania, and West Virginia were conducted. Field tests of the transmission of low-frequency (20 hz to 20,000 hz) signals by vertical axis loops and horizontal wire antenna were made and compared with theoretical predictions. Implications of the field tests for the design of an electromagnetic system to locate trapped miners are discussed.