Millimeter-Wave Dielectric Properties of Highly Refractive Single Crystals Characterized by Waveguide Cavity Resonance.

This paper reports precision measurements of the electromagnetic permittivity of five highly refractive, single-crystal materials, SrTiO3, KTaO3, rutile TiO2, LiTaO3, and LiNbO3, using a single, well-controlled, frequency-scalable procedure over the frequency ranges 25–110 and 140–220 GHz. Real permittivity values were highly consistent for different samples measured across multiple frequency bands. For SrTiO3, KTaO3, and TiO2, real permittivities were more consistent with lower frequency values than typically reported in the millimeter-wave region of the spectrum. Real permittivities of LiTaO3 and LiNbO3 agreed with most reported data. The intrinsic dielectric loss of SrTiO3, KTaO3, and the extraordinary axis of rutile TiO2 was also characterized over the ranges 25–110 and 140–220 GHz, and intrinsic loss per unit frequency was found to be consistent with values measured at other frequencies by dielectric resonators and quasi-optical techniques. [ABSTRACT FROM AUTHOR]