Measurement of the Dielectric Constant and Loss Tangent of Thallium Mixed Halide Crystals KRS-5 and KRS-6 at 95 GHz

The dielectric constants and loss tangents of KRS-5 and KRS-6 thallium halide mixed crystals have been measured at 95 GHz using both the shorted waveguide (SWG) reflection method and the Fabry-Perot (F-P) transmission method on samples filling standard WR-10 waveguide. The results--KRS-5: epsilon´ _r = 31; tan delta = 1.8 x 10 ^-2; KRS-6: epsilon´ _r = 29, tan delta = 2 x 10/sup-2/-- agree reasonably well with a simple theoretical fit to the far-infrared Iattice absorption of TIBr and TICI centered at about 1400 GHz. The dielectric samples were hot-pressed into copper wafers with dimensions matching WR-10 waveguide, and then machined and polished to obtain flat, parallel air-dielectric interfaces.