Welcome to CDC stacks |
Stacks Logo
Advanced Search
Select up to three search categories and corresponding keywords using the fields to the right. Refer to the Help section for more detailed instructions.
Clear All Simple Search
Advanced Search
Medium-Frequency Propagation In Coal Mines
  • Published Date:
Filetype[PDF-402.32 KB]

  • Description:
    Medium-frequency (MF) waves can propagate in a coal seam, bounded above and below by conducting rock, in an approximate transverse electro-magnetic (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, trolleylines, 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.

  • Subject:
  • Main Document Checksum:
  • Supporting Files:
    No Additional Files
No Related Documents.
You May Also Like: