Millimeter Wavelength Prime Resonance Spectra for High and Low-Conductivity Fibrous Aerosols

Spectral dependence of the millimeter wavelength extinction due to two fibrous aerosols were measured over a frequency range spanning the primary attenuation peak. For contrast, two conductivities were selected, one representing polyacrylonitrile (PAN) graphite and the other is a metal-coated version incorporating the PAN core. Aerosol densities were measured to determine the mass-specific values of extinction. Aerosol length and diameter distributions were measured to provide parameters for comparison with theory. Both measurements and theory show a much stronger attenuation resonance for the higher conductivity material. At the resonance frequency, for which the particle length is approximately one-half the wavelength, the extinction efficiencies differ by about a factor of 3.