Characteristics Calculation of Ferrite Material Using Frequency Tunable Resonator

This paper presents an efficient method to measure the permittivity, permeability, and magnetization of ferrite at various resonance frequencies of ferrite resonator. A cylindrical dielectric rod is inserted to annular ring ferrite for tuning the resonance frequency of the ferrite resonator without changing the length of the resonator. The permeability and permittivity of ferrite are calculated using a characteristic equation for resonator in a demagnetized state. The permittivity is compared with the measured results by the cavity perturbation method to verify the calculated results. We analyzed the electromagnetic fields in each region of ferrite, and derived 8 × 8 eigenvalue matrix for the mode-splitting behavior on the HE
₊₁₁₁
/HE
_-111
mode. The induced magnetization of ferrite in the partially magnetized state is calculated by a nonlinear system with the measured resonance frequency. The calculated magnetization of the resonator is a critical parameter to analyze ferrite material, so the calculated results are verified by the magneto-static simulation based on the measured data of B-H curve. Finally, the permeability tensor components at various frequencies are obtained by statistic equations.