Measuring and Reporting High Quality Factors of Inductors Using Vector Network Analyzers

Accurate measurement of high quality factors in inductors is a challenging task. While Q values in the range of 30 and below can be assessed using network analyzers with standard calibration techniques, reporting Q values of 50 or higher demands careful consideration of the type of calibrations used, the accuracy of the instrumentation and associated reference standards, and of the effects of the testing structures involved. This paper examines the accuracy of network analyzers operating in the VHF through S -band range with short-open-load calibrations, and shows that these common instruments can provide accurate Q measurements up to several hundred or more, but only if special care and methods are used.