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Medium-frequency propagation in coal mines.

Authors
Sacks-HK; Chufo-RL
Source
Proceedings of the Fourth WVU Conference on Coal Mine Electrotechnology, August 2-4, 1978, Morgantown, West Virginia. Morgantown, WV: West Virginia University, 1978 Aug; :27.1-27.12
Link
NIOSHTIC No.
20032395
Abstract
Medium-frequency (MF) waves can propagate in a coal seam, bounded above and below by conducting rock, in an approximate transverse electromagnetic (TEM) transmission-line mode with the electric field vertical and the magnetic field horizontal. The theory of this coal seam mode is applied to recent MF data for a number of mines in order to classify the propagation characteristic of the mines in a simple way. When conductors such as rails, trolley lines, or power cables are present in the vicinity of the measurement path, it is found that the magnetic field versus range plots have two distinct regions with very different slopes. This effect is attributed to coupling of the cylindrically spreading coal seam mode to a low-attenuation conductor guided mode. As a result, voice communications range between mobile transmitters can extend several thousand meters. The use of MF for mine communications is discussed.
Keywords
Mining-industry; Underground-mining; Coal-mining; Radio-waves; Electronic-devices
Publication Date
19780802
Document Type
Conference/Symposia Proceedings
Fiscal Year
1978
NTIS Accession No.
NTIS Price
NIOSH Division
PRC
Source Name
Proceedings of the Fourth WVU Conference on Coal Mine Electrotechnology, August 2-4, 1978, Morgantown, West Virginia
State
PA; WV
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