Measurement of propagation coefficient beyond a waveguide junction

A method is described for measuring the propagation coefficient of an unknown guide with an unknown junction interposed between the guide and the measuring equipment. The method requires the use of only two lengths of unknown guide, but involves terminating the guide, through a junction identical to the first, with a further section of measuring guide containing a movable piston. The method can be extended to guides in which only an evanescent mode is present. It was successfully used for measuring the propagation coefficient in longitudinally magnetized ferrite-filled circular guide.