New approach for open resonator analysis for dielectric measurements at mm-wavelengths

Impedance transformation theory has been applied in order to describe a spherical Fabry-Perot resonator with monolithic dielectric samples at different positions along the resonator axis. The information due to different sample positioning in the resonator allows increasing accuracy in the evaluation of dielectric properties. Low loss materials like CVD-diamonds were taken as test specimens. The formalism can be extended to the case of sequences of dielectric layers. Experimental and modelling results are presented for two cases of sample geometry: resonant and anti-resonant. As an example the influence of additional surface loss on resonator parameters is quantified.