Effect of the dielectric filling on the phase behaviour of the circular waveguide with azimuthally magnetized ferrite toroid and dielectric cylinder

The phase characteristics of the circular waveguide, comprising an azimuthally magnetized ferrite toroid and a dielectric cylinder of relative permittivity, larger than that of the ferrite, under normal TE₀₁ mode excitation, are figured. The analysis reveals that they are finite for both directions of magnetization, limited by the cut-off frequencies and by specific envelope lines, depending on certain positive real numbers (L numbers), related to the roots of the characteristic equation of the structure. The expansion of the region, occupied by dielectric and the increase of its relative permittivity entails a moving of the position and a shortening of the length of the curves mentioned (a shrinking of the areas of wave propagation), as well as a change of the sign of the differential phase shift provided.

I. Introduction

The circular waveguides, entirely filled with azimuthally magnetized ferrite or containing coaxially positioned layers of ferrite of the magnetization pointed out and dielectric that support normal mode, possess potentialities of nonreciprocal digital phase shifters [1]–[12]. The experience has shown that the investigation of their propagation properties is a difficult task and this has thrown back the authors in the field upon the use of different approaches for its solution [1]–[12]. One of them is the method, employing complex confluent hypergeometric functions for the analysis of waves in the anisotropic areas and real cylindrical ones for the dielectric strata, combined with iterative techniques [4]–[12]. Recently, it has been applied to study a two-layered configuration whose central part is occupied by dielectric and its outer one - by ferrite. To facilitate the mathematical model of the problem as much as possible, the values of relative permittivities of both media have been assumed equal [8], [10], [12].