A novel method for cavity parameter measurement

A novel swept frequency method for cavity parameter measurement applicable to both transmission- and reflection-type resonators is presented. Signals proportional to the input reflection coefficient squared |S₁₁|² and/or signals proportional to the transducer gain squared |S₂₁|² of the cavity under test and of a reference cavity, e.g., a wavemeter, are combined in an XY-plot to give closed-loop curves. These curves may be simply evaluated for accurate values of all cavity parameters, as there are resonant frequency, loaded Q-factor, and coupling coefficients. Thus the simplicity of swept frequency techniques and the accuracy of more sophisticated methods are combined to give, upon proper averaging several independently obtained results, an accuracy of better than ±1 per cent.