Modes in lossy stratified media with application to underground propagation of radio waves

The problem considered is that of determining the complex propagation constant of a plane wave on a flat layer of lossy dielectric with a loss-tangent of less than one, and of uniform thickness, surrounded on both sides by identical layers having a loss-tangent greater than one, and thicknesses much larger than the skin depth. A formula given, relates this propagation constant to the path loss between two antennas provided their excitation efficiencies are known. As an example, curves showing attenuation and wavelength are given for the following properties of the layers: Middle layer =
\sigma = 10^{-6}
(ohm meter)
^{-1}
,
\epsilon_{r} = 10, \mu_{r} = 1
. Surrounding layers =
\simga = 10^{-2}
(ohm meter)
^{-1}
,
\epsilon_{r} = 10
,
\mu_{r} = 1
. Frequencies between 1 kc and 10 Mc are covered, as well as values on thickness of the meddle layers ranging from 10 m-200 m. (The computations were performed under the direction of John Nihen).