Lithospheric Radio Propagation Modelling a Feasibility Study.
Final rept. 1 Sep 78-28 Feb 79,
DEBETTENCOURT (JOSEPH T) NEWTON MA*
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Radio wave propagation in the earths crust is reviewed. This has been studied by many investigators who usually assume the crust to be a planar slab of low loss-tangent, bounded on top and bottom by regions of large loss-tangent. Available conceptual depth profiles of complex dielectric constant of the lithospheric waveguide are reviewed and theories extant summarized. Sources were usually VEDs inserted through vertical bore-holes. For ocean emplaced antennas located near the ocean-lithosphere boundary, the sources are horizontally polarized and propagation is predominantly by means of lateral waves. Calculations are reported for a wide range of conditions. The useful characteristics of lateral wave transmission are discussed. The measured properties of scaled waveguide propagation that have been reported could not accurately scale the losses in the overburden since it was represented by a metal plate. The principles of electrodynamic similitude are delineated and two different experiments using similitude with different depth profiles are discussed.
- Radiofrequency Wave Propagation