Calculation of phase and attenuation constants for waveguides loaded with lossy ferrite with longitudinal or transverse magnetisation

In the paper, a finite element method with edge elements for directly calculating the phase and attenuation constants of ferrite-loaded waveguides with longitudinally or transversely magnetised directions is presented. The magnetic losses of the ferrite are included in the form of a Landau-Lifshiz damping term. Dispersion characteristics with attenuation of a rectangular waveguide loaded with a ferrite slab are in very good agreement with the analytical results, which confirms the correctness of the method. The analysis for a coplanar waveguide with a ferrite layer is also carried out. The calculation shows that a larger differential phase shift and lower attenuation can be achieved with transverse magnetisation than with longitudinal magnetisation at higher frequencies