Electric field tunable ferrite-ferroelectric hybrid wave microwave resonators: Experiment and theory

The electric field tuning characteristics of a combined microwave resonator based on ferrite-ferroelectric layered structure have been studied in a wide range of bias magnetic fields. The combined ferrite-ferroelectric resonator was composed of two rectangular resonators fabricated from a ceramic barium strontium titanate (BST) slab and a single-crystal yttrium iron garnet (YIG) film. The in-plane dimensions for the YIG and BST resonators were chosen to be equal in order to maximize the electromagnetic coupling between their main modes and reduce spurious influence of their higher order modes. A tuning range of 100 MHz for the resonator frequency was realized at 5 GHz through the variation of magnetic permeability and dielectric permittivity of the YIG-BST structure. A theory for the hybrid wave excitations, based on a coupled-mode approach, has been developed and provides good description of the data. (c) 2006 American Institute of Physics.