Above-the-earth field contours for a dipole buried in a homogeneous half-space.
Pittsburgh, PA: U.S. Department of the Interior, Bureau of Mines, RI 8781, 1983 Sep; :1-14
An essential element of the Bureau of Mines electromagnetic location and communication system for trapped miners is a quantitative knowledge of the surface and above-surface electromagnetic fields created by an underground transmitter. The field solutions given in this report use approximations in which the displacement currents are negligible for low frequencies. The earth is represented by a homogeneous half-space model in which a dipole source is immersed. The vertical magnetic field equipotential contours at and above the surface are graphically mapped. The volumes of the regions bounded by these contours are directly related to the geometrical zones of signal detectability. Knowledge of the detectability zones will enable the proper search strategies to be developed for airborne detection of trapped miners.
Mine-gases; Mining-industry; Methanes; Methane-drainage; Methane-control; Explosive-gases; Explosive-atmospheres; Underground-mining; Coal-mining; Control-technology; Engineering-controls
IH; Report of Investigations
NTIS Accession No.
Pittsburgh, PA: U.S. Department of the Interior, Bureau of Mines, RI 8781