Cut-off characteristics of the normal TE0n modes in the circular waveguide containing an azimuthally magnetized ferrite cylinder and a dielectric toroid

A method for computation of the positive purely imaginary roots of the characteristic equation of the circular waveguide with a ferrite cylinder of azimuthal magnetization and a dielectric toroid, propagating normal TE_0n modes, derived by complex Kummer confluent hypergeometric and real Bessel and Neumann functions, is developed. Employing it, a numerical analysis is performed of the dependence of those of them which correspond to a zero imaginary part of the complex first parameter of Kummer functions, on the modulus of off-diagonal ferrite permeability tensor element |α| and the anisotropic cylinder to transmission line radius ratio ρ, assuming equal values of the relative permittivities of the two media. The discussion is confined to the first roots only - to the TE₀₁ mode. Based on this study, the cut-off characteristics of the latter in the configuration (the distribution of the normalized towards frequency and ferrite relative permittivity critical guide radius for the same vs. ρ with |α| as parameter and to |α| with ρ as parameter) are (is) counted. The results obtained are illustrated numerically and graphically. They could be used in designing nonreciprocal microwave ferrite control components.