LITHOSPHERIC RADIO PROPAGATION. A REVIEW,
Abstract
The feasibility of linking sub-surface stations by radio propagation entirely thru the rocks of the earth's crust, over paths several hundred to thousands of kilometers long, depends upon several sets of critical geophysical factors. Among these are: (1) the geologic structure of the crust; (2) the compositional variations of the major rock facies, both laterally and in depth; (3) the electrical conductivity, dielectric permittivity, and intrinsic attenuation of these rock facies as a function of temperature, frequency, and pressure; (4) the temperatures and temperature gradients in the crust. Little is known about these properties of the crust by direct observation below a depth of about 3 Km, but (by extrapolation and inference) if any favorable zone does exist, it will be found between depths of about 6 to 25 Km. Current knowledge does not rule out the probability of achieving radio communication thru the crust, but several unfavorable aspects are revealed by careful analysis of the geophysical factors. Some recent experiments in shallow boreholes (less than 3 Km deep) have yielded results which are at best ambiguous, but not conclusive. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 01, 1966
- Accession Number
- AD0701017
Entities
People
- S. Benedict Levin
Organizations
- United States Army Communications-Electronics Command