Open resonator mode patterns for characterization of anisotropic dielectric substrates for HTS thin films

An open resonator possesses a unique combination of advantages for characterizing the millimeter-wave losses of today's best HTS thin films and substrates. One of the primary advantages is the transverse linearly-polarized electric field of the TEM00q modes, which induces a polarized current in any HTS, dielectric, or semiconductor sample placed inside the resonator. The polarized current flow allows detection and quantification of any material anisotropies. To provide an intuitive understanding of the field and current distributions in an open resonator, mode patterns computed with a finite-difference time-domain model are presented. The theory of open-resonator anisotropic-dielectric testing is reviewed, and measured anisotropic dielectric constants of sapphire, LaAlO3, and NdGaO3 substrates are listed.