A tunable hexaferrite dielectric resonator for W-band devices

Magnetic field tuning characteristics of a single-crystal barium hexaferrite dielectric resonator in the frequency range 75-110 GHz are reported. The dielectric resonances occur at a much higher frequency than the ferromagnetic resonance. It is shown that the degeneracy in the dielectric mode is lifted with an applied magnetic field H and that the modes can be tuned by 10 GHz or more with H. The dielectric modes are of importance for the realization of low-loss devices, including resonators, isolators and phase shifters.