Experimental investigation of the `post mount´ structure in waveguide-type SIS mixers

A x70 scale model for a W-band waveguide-type SIS mixer mount has been fabricated and employed to investigate the `post mount´ structure, that is, a planar structure (on the quartz substrate) located in the waveguide for mounting an SIS junction (array). To collect accurate impedance data for the simulation of the equivalent circuit model of the `post mount´, a novel measurement technique is proposed. The equivalent lumped parameters have been extracted for various configurations of the `post mount´, by fitting the measured RF impedances. Their dependencies on the boundary condition under which the `post mount´ is located, are examined through several simulations based on the finite element method. Finally, the embedding impedances of the scaled mixer mount are calculated in terms of the established equivalent circuit model of the `post mount´, and are compared with those calculated by the Eisenhart-Khan model