Millimeter Wave Dielectric Permittivity Measurements of Common Materials

Millimeter-wave transmittance measurements of common household powdered materials over the frequency range spanning from 35 GHz to 120 GHz. Frequency dependences of real and imaginary parts of the dielectric permittivity have been calculated from the transmittance spectra. This wide band spectroscopy makes use of a backward wave oscillator as a high power tunable source of radiation which is preferable for the measurement of high absorbing materials due to the higher level of radiation transmission through the sample.