Some properties of the zeros of Kummer function and their application in the analysis of the circular waveguide completely filled with azimuthally magnetized ferrite

The Kummer function method is one of the most promising tools for investigation of normal and slow TE_0n modes in the circular waveguides, loaded with co-axially positioned azimuthally magnetized ferrite cylinder [1]. Compared to other approaches, elaborated for the purpose [2-5], its main advantage consists in the very well developed theory of the function mentioned [6] which facilitates the solution of propagation problems and in the possibility to obtain exact results. Competitive to it are the technique, using the Whittaker first function [7] and the quite recently suggested one, employing the regular Coulomb wave function [8].