Electromagnetic wave propagation in a coaxial waveguide with an annular magnetized ferrite rod

Abstract

The propagation of electromagnetic waves in a coaxial waveguide loaded with ferrite is studied by using the exact analysis approach. The results of the partially filled ferrite case (radii ratio 'So = 0.5') and the approximately fully filled ferrite case (radii ratio 'So = 0.9') are given for the dipolar modes (n = ±1). The ferrite used is assumed to be lossless and completely magnetized. A review of the electromagnetic wave propagation in an infinite ferrite medium is presented to point out the various wave propagation characteristics in the parametric space diagrams. In the exact analysis method, the general dispersion relations are derived directly from Maxwell's equations. Initially, the cutoff and resonant frequencies are examined analytically to predict all possible modes. By employing numerical root search technique the complete dispersion characteristics are obtained. -- The occuring modes in the different parametric regions are identified and properly classified to provide a better understanding of the basic mode structure in these types of waveguides which are filled with anisotropic materials. Also, the effects of the radii ratio and the dc magnetic field on the various modes are discussed. Finally, some applicational aspects of such waveguides are considered, especially, in the design of phase shifters where the characteristics of the pairs of dominant waveguide modes play an important role.