Modeling and Characterization of Microstrip-to-Coaxial Transitions

A simple circuit model for the transition from a Iossy microstrip to coaxial line has been developed on an experimental basis. The proposed model can be used to predict accurately the insertion loss and insertion phase over a wide frequency range. Since explicit formulas for the model element values are given, these elements, representing the parasitic of the transitions, can be taken into account very easify when the microstrip is used as a test fixture for measuring the parameters of solid-state devices. The practical use of the model has been examined for several Z₀=50-omega lines on both Epsilam-10 and 99-percent alumina substrates with standard SMA coaxial connectors.