Miniaturized Coaxial Coupling Enhances the Millimeter-Wave Q-Factor of Fabry-Perot Open Resonator for Dielectric Material Characterization

A new version of a coaxial loop-coupled Fabry-Pérot open resonator (FPOR) with a significantly enhanced Q-factor is reported. Measurements have been performed in the $40 \mathrm{GHz}-130 \mathrm{GHz}$ range. The resonator is coupled using a 0.6 mm diameter coaxial line located at the center of each mirror Compared to an FPOR coupled with a 1.0 mm diameter coaxial line, the $\mathbf{Q}$-factor increase is up to $\mathbf{1 0}$-fold.