Weak multiphonon bands dominate absorption at the lower absorption band edge which lies in the THz and submillimeter spectral regions for radome materials of interest. The strongly temperature dependent behavior of these bands extends into the microwave, and likewise governs temperature dependent behavior of microwave permittivity. By considering theoretically the expected frequency and temperature dependence of these bands, a classical oscillator model of permittivity is developed which accurately models dielectric behavior from infrared through the microwave frequencies. Using infrared and far infrared transmittance and reflectance spectra to characterize the absorption band and band edge, semi-empirical models of temperature dependent dielectric properties are developed for three standard materials as proof of principle: o-ray sapphire, Pyroceram© 9606, and zinc sulfide.
Proceedings Title: The 13th DoD Electromagnetic Windows Symposium
Conference Dates: May 18-20, 2010
Conference Location: Pensacola, FL
Pub Type: Conferences
classical oscillator model, multiphonon absorption, multiphonon difference bands, pyroceram dielectric properties, sapphire dielectric properties, submillimeter spectroscopy, THz spectroscopy