Measurement of the complex dielectric constant down to helium temperatures. II. Quasioptical technique from 0.03 to 1 THz

A quasioptical method is described that allows the determination of the complex dielectric constant almost continuously in the millimeter wave regime without the use of electrical contacts. The technique allows the dielectric properties of bulk samples (solids, powders, and liquids) and thin films (free standing or deposited on a substrate) to be measured with excellent absolute accuracy down to 2 K.