Q-factor measurement with a scalar network analyser

Abstract

An accurate determination of the unloaded Q-factor of RF and microwave resonators is required when the electrical properties of materials are being measured or when the resonator is to be characterised for an application in a filter or an oscillator. A procedure is described of weighted least-square curve fitting to the measured magnitude of the reflection coefficient. The accuracy of the results is significantly improved by incorporating coupling losses in the equivalent circuit model.