Millimeter-Wave Transmittance and Reflectance Measurement on Pure and Diluted Carbonyl Iron

Transmittance and reflectance measurements on highly absorbing carbonyl iron materials over a broad millimeter-wave frequency range have been performed. The frequency dependence of the complex dielectric permittivity of a carbonyl iron diluted composite and pure powdered materials has been determined in the millimeter waves for the first time. The measurements have been employed using a free-space quasi-optical millimeter-wave spectrometer equipped with a set of high-power backward-wave oscillators as sources of coherent radiation, which are tunable in the range from 30 to 120 GHz. A significant transmission zone of millimeter-wave radiation at a frequency around 60 GHz has been observed in the transmittance spectra for the carbonyl iron materials.