Automatic Microwave Q Measurement for Determination of Small Attenuations

The Q´s of a waveguide transmission cavity with and without insertion of a length of waveguide give the insertion loss. Least-squares fitting of transmission versus frequency data have been used to determine Q and resonant frequency f_r with computer-controlled equipment in an iterative process. Preliminary values of Q and f_r are used to calculate an improved set of test frequencies, and so on. A rapid least-squares method is described which minimizes truncation errors.