Electromagnetic Communication in the Earth's Crust
Abstract
This report presents results of an analysis of the capabilities that might be achieved with a lithospheric communication system. The analysis uses several available models of continental lithospheric conductivity as inputs to calculations of transmission characteristics and possible communication system parameters. Because of prevailing uncertainties, significant differences exist among the various models; and a wide range of future system capabilities is found to lie within the realm of possibility. For all models used, the calculated attenuation rates are considerably larger than for above-ground transmission, which depends on propagation in the earthionosphere waveguide. In spite of this fact, reasonably large transmission ranges might be possible in the lithosphere because the atmospheric noise fields at depth are very small, having suffered heavy attenuation in propagating downward from the earth's surface. The major factor affecting system feasibility is whether water- saturated microcracks exist in all major rock types at depths greater than, say, 5-to-8 km. If such microcracks exist (as assumed in one model), and minimum conductivities in the crust exceed 1/100,000 to 1/1,000,000 mhos/m, then the calculations show clearly that a practical communication system is not feasible. For this case, the attenuation rates are so high that only very short transmission ranges could be achieved, even if large amounts of power were expended.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jun 01, 1973
- Accession Number
- AD0913801
Entities
People
- Edward C. Field
- Michael Dore