Cutoff Frequencies of Fully Anisotropic Circular Waveguides With Oblique External Magnetic Bias

In this letter, the cutoff frequencies of multilayered fully anisotropic circular waveguides with metallic walls are calculated in the general case, in which the waveguide’s anisotropic material is magnetized by an external magnetic bias which is obliquely oriented with respect to the waveguide’s axis. This is a generalization of cases where the bias is aligned to the waveguide’s axis and the material features gyrotropic behavior. This problem is solvable via a coupled-field volume integral equation-cylindrical Dini series expansion (CFVIE-CDSE) method, previously used for the calculation of electromagnetic (EM) scattering by anisotropic cylinders with oblique magnetic bias, by combining formerly constructed modified tensorial Green’s functions (GFs) to account for the boundary conditions (BCs) on the metallic walls. We validate the extended CFVIE-CDSE method with the HFSS commercial software and we study a microwave application of a G-610 aluminum garnet ferrite-loaded waveguide, magnetized under oblique magnetic bias, where we compute the complex cutoff frequencies.