Propagation along unbounded and bounded dielectric rods. Part 1: Propagation along an unbounded dielectric rod

The paper describes a method for evaluating the propagation coefficients of an unbounded lossless dielectric rod of infinite extent. The propagation coefficients are obtained as a function of the ratio of rod radius to free space wavelength, r1/¿0, for the three lowest modes of propagation possessing fields with ¿ dependence of the form ¿±j¿. The method of solution enables the form of the complete mode spectrum to be identified. It is also established that the product of the rod permeability and permittivity, ¿¿, primarily determines the propagation behaviour; the ratio ¿/¿ has only a secondary effect. An expression is obtained for the distribution of transmitted power between the rod and the surrounding space, and it is also demonstrated that the product ¿¿ primarily determines this quantity. Correlation between power distribution and attenuation is demonstrated for a rod possessing small losses.