MEASUREMENT OF RESONANT-FREQUENCY AND QUALITY FACTOR OF MICROWAVE RESONATORS - COMPARISON OF METHODS

Precise microwave measurements of sample conductivity, dielectric, and magnetic properties are routinely performed with cavity perturbation measurements. These methods require the accurate determination of qual ity factor and resonant frequency of microwave resonators. Seven diffe rent methods to determine the resonant frequency and quality factor fr om complex transmission coefficient data are discussed and compared to find which is most accurate and precise when tested using identical d ata. We find that the nonlinear least-squares fit to the phase versus frequency is the most accurate and precise when the signal-to-noise ra tio is greater than 65. For noisier data, the nonlinear least-squares fit to a Lorentzian curve is more accurate and precise. The results ar e general and can be applied to the analysis of many kinds of resonant phenomena. (C) 1998 American Institute of Physics.