Resonant mode characteristics of a magnetostatic resonator in yttrium iron garnet (YIG) films

In this paper, the performance of a magnetostatic surface wave straight edge resonator (MSSW-SER) is extensively studied, including the mode field distribution, the unloaded quality factor of the fundamental mode and coupling to the external circuit. Measurement of the magnetic field distribution on a MSSW-SER is found to be useful for identifying the mode number. The unloaded Q-value of the fundamental mode, which includes magnetic loss and conductor loss, and also the external Q are measured to give design data for tunable band-pass filters. Moreover, an equivalent circuit is set up to analyze the external Q; and verified by experiment. Under higher power excitation: a novel performance of the MSSW-SER is found in YIG films that is, the resonant frequency shifts to the lower side and the unloaded quality factor tends to decrease. These phenomena caused by the nonlinear effect of a MSSW-SER are analyzed by means of the nonlinear MSSW dispersion relation. The above methods can be easily extended to study two other modes, magnetostatic forward volume wave (MSFVW) and magnetostatic backward volume wave (MSBVW) resonators.