AnActive Frequency Technique forPrecise Measurements on Dynamic Microwave CavityPerturbations

A new method forthedynamic measurement ofthe passive parameters ofa microwave cavity isdescribed. Boththe resonant frequency (.fts) andtheloaded Qfactor (QL,) aremeasured simultaneously fromactive frequency signals generated byaclosed- loop circuit containing thetestcavity. Resonant frequency deviations ofupto20MHz aremeasured with anaccuracyofbetter than +0.25 percent, andloaded Q-factor variations (from 500to7000) are measured withan accuracyofbetter than+1.2percent. The unperturbed cavity resonancewasat2452.0249 MHz,andthetime of measurement ofeachcavity parameter was < Is. I. INTRODUCTION