Q Measurement of Strongly Coupled Cavities (Correspondence)

The long-line method herein described provides a rapid, simple, and fairly accurate measurement of resonant frequency and loaded bandwidth of a one-port cavity which is tightly coupled to its transmission line. Such tightly coupled cavities are often used as signal couplers in beam-type electron tubes. The cavity itself has a very high unloaded Q, and the beam loads the cavity to give a loaded Q approximately equal to the external Q (i. e., the beam is matched to the coupler's transmission line).