Novel approach to the characterization of coaxial-to-microstrip transitions

Resonance measurement method has been employed in the procedure leading to coaxial-to-microstrip equivalent circuit determination. In comparison with previous approaches which used reflection or transmission measurements, the proposed method has the advantage of superior accuracy of measurements and may be implemented using scalar network analyzers. Discontinuities in connector's coaxial part have been accounted for. In addition, transition losses have been modelled by a frequency-dependent resistance. Equivalent circuits of two SMA-microstrip connectors have been presented. In one case the characterization has been extended to 30 GHz, covering thus the whole SMA connector operating frequency range. The accuracy of characterization has been confirmed by measurements on a pair of connectors separated by a section of microstrip. Potential applications of equivalent circuits obtained in such a way have been also discussed.