Measuring techniques and calculation procedures for complex dielectric constants are extended to temperature ranges 4 to 2000 degree K, and frequency C.008 Hz to 90 GHz. BN, Si02, sapphire, and spinel, all of which have good high-temperature properties, were tested. Methods of interpreting dielectric data and computer programs for finding the components of complex spectra are discussed. Measurements data are presented in graphical and/or tabular form. (KF-PL).