Hemispherical quasi-optical dielectric resonators as possible sensors for impedance measurements of superconductors

In the present paper a problem is set to investigate the spectrum and Q-factor hemispherical quasi-optical dielectric resonators (QDRs) and specialities of their excitation as well as to evaluate filling coefficient A_s of a conductor. The resonator made of Teflon and ceramics BaMgTaO (BMT) proved by Murata are studied. The Teflon resonator and BMT ones are fulfilled in such a way that their electrical dimensions are nearly equal. The measurements are performed in Ka-band at room temperature for Teflon resonator and in 77 K-300 K temperature interval for BMT. It is experimentally shown that in hemisphere QDR with the impedance endplate the WG mode waves are excited and spread along the plate. The waves can be of two types H and E. Both waves are excited by means of image dielectric waveguides. For the purpose of the impedence measurement of conductors and superconductors, preference must be given to H-waves. The QDRs are applied for impedance measurements based on superconductors.