Surface-Wave Propagation Over a Coated Plane Conductor

Abstract

A TM-type wave is assumed propagated parallel to the surface of a plane conductor coated with a thin layer of dielectric. This wave is similar to the wave propagated over a dielectric-coated wire of circular cross section, discussed by Dr. Goubau in the references. Analysis of the cylindrical type wave requires the use of Hankel functions, while the wave over a plane surface may be described by simpler functions, namely, trigonometric functions in the dielectric layer and real exponential functions in the adjacent air region. The calculations thus are considerably simplified and the wave properties more readily observed. Basic equations are developed for both dielectric layer and air regions, which indicate a criss-cross or multiply reflected wave in the dielectric and a unidirectional wave in the air. Equations are developed also for the electric flux line shapes, power propagated over the cross section, concentration of power flow in neighborhood of the film, attenuation due to conductor wall loss and dielectric film loss. Numerical calculations are given for five film thicknesses varying from 0.0001 to 0.01 meter and for five frequencies ranging from 3×108 to 3×1010 cycles per second.