Evaluating Resonant Cavity Surface Treatment Procedures with a New Unloaded Q-Factor Measurement Method

Numerous unloaded Q-factor measurement methods exist, typically limited to a narrow band around the resonance frequency. These methods also suffer from a substantial variation between measurements with different coupling coefficients. A new VNA-based method is implemented, which considers the parasitic effects of the coupling mechanism in order to allow for measurements in a broader frequency band and reduce the aforementioned variation. To validate the proposed method, aluminum alloy based waveguide cavities were built and measured. Compared to existing methods, the proposed method shows a reduction of coupling coefficient induced Q₀ variation. Two common unloaded Q-factor improvement techniques for waveguide cavity resonators are investigated during the validation process.