Measurement of High Q Cavities at 10,000 Megacycles

Known methods of measuring Q in high Q resonant cavities, together with their accuracies and sources of error are discussed. For relatively low values of Q and of frequency, it is shown that band width methods are more accurate than decrement methods. For values of Q above 30,000 at frequencies above 3,000 megacycles the reverse is true. The significant feature of the present method, the wide range heterodyne decrement method, is that the accuracy is improved by observing the decay over a relatively long interval of time. An absolute accuracy of plus or minus three per cent and a relative accuracy of plus or minus two per cent are achieved. Design features and performance are discussed and constructional details are presented.