Some Features of the Circular Ferrite-Dielectric Waveguide Phase Shifter of Azimuthal Magnetization

The lower and upper cut-off frequencies and the width of the work area of a digital phase shifter, built on a circular waveguide, containing a co-axially positioned azimuthally magnetized latching ferrite cylinder and a dielectric toroid, under normal TE
01
mode excitation, are investigated. The size of anisotropic region is assumed large and the relative permittivities of both strata–equal. The off-diagonal element of ferrite permeability tensor changes in the whole interval in which it has sense. The analysis is based on the characteristic equation of the structure, derived earlier in terms of complex Kummer confluent hypergeometric and real ordinary Bessel and Neumann functions, and on its phase curves, plotted before, too. It indicates that for any set of parameters the transmission line has one lower and two upper cut-off frequencies. They specify the condition for phase shifter operation of the device and the width of the area in that it is fulfilled. The lower frequencies are determined with the help of the roots $\bar{\xi}_{0, n}^{(c)}$ of the equation mentioned in its purely imaginary independent variable, computed for a zero value of the imaginary part of the complex first parameter of Kummer functions. The upperby means of the real positive $\overline{L}_{3\pm}$ numbers, advanced recently by the authors, calculated, using the same roots, but for infinitely large positive and negative numerical equivalents of the imaginary part referred to. Detailed computations of $\bar{\xi}_{0, n}^{(c)}$ and $\overline{L}_{3\pm}$, of the cut-off frequencies and of the width of the area in question are performed. The effect of off-diagonal tensor element on all results is studied. It is established that in certain cases the configuration does not provide phase shift at all.