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Abstract

This work consists of two parts. The first part is a comprehensive study of surface-wave propagation along dielectric tube waveguides. It includes the derivation of the characteristic equations and expressions for group velocity and attenuation coefficient, the latter by a perturbation method. Mode designations are justified and the physical distinction between the HE₁₁ and EH₁₁ modes is further illustrated by showing three-dimensional plots of the field configurations. Computed characteristics are given for a wide range of parameters, and are compared with those of standard rectangular waveguides. Finally, a method of shielding the tube from weather conditions is proposed and the resulting changes in characteristics are noted. The second part of this work is essentially a unified analysis of all slow-wave modes in eight cylindrical waveguides. Characteristic equations are derived and expressions are obtained for the group velocity and the attenuation coefficients by a perturbation method. Accurate propagation characteristics for the dominant TM₀₁ mode are computed for four waveguides with no restrictions on their radial dimensions. These guides are the Goubau line and a coaxial cable with dielectric linings on the inner, outer, or both conductors.