Small signal characteristics of ferroelectric ceramics at millimeter wavelengths

A method is described for measuring dielectric properties at wavelengths near 1 mm. The particular material tested was a ferroelectric ceramic composition of 73 per cent barium titanate-27 per cent strontium titanate. Material properties were determined from transmission measurements through an interferometer, and the radiation was generated by a magnetic undulator. It was found that there was a marked dispersion in dielectric constant for this material in the range from 50-100 kMc.