Random and systematic uncertainties of reflection-type Q-factor measurement with network analyzer

The reflection-type measurement of the unloaded Q factor of microwave resonant cavities consists of measuring the complex reflection coefficient with a network analyzer as a function of frequency and fitting the measured data to a circle on a complex plane. The measurement errors are of two kinds: random errors caused by imperfect data fit to an ideal circle and systematic errors caused by the limited accuracy of the network analyzer and its accessories. This paper presents the methods for estimating the measurement uncertainties for both kinds of errors.