On the Measurement of Microstrip Discontinuity Scattering Matrices by a Resonance Technique

A new simple solution to the problem of experimentally characterizing the behaviour of symmetrical microstrip discontinuities is presented. To perform the measurement, a resonant cavity consisting of a couple of identical microstrip sections connected by the discontinuity to be tested is built, together with a reference circuit made of a length of uniform transmission line. The resonant frequencies of the test and reference device are then measured as accurately as possible, and the scattering parameters of the discontinuity are related to these frequencies by means of very simple, explicit formulae.