  The dielectric properties of selected conductively-loaded polyimide samples
are characterized in microwave through far infrared wavebands. These materials,
belonging to the Vespel\textsuperscript{\textregistered} family, are more
readily formed by direct machining than their ceramic loaded epoxy counterparts
and present an interesting solution for realizing absorptive optical control
structures. Measurements spanning a spectral range from 1 to 600\,${\rm
cm^{-1}}$ (0.03 to 18\,THz) were preformed and used in parametrization of the
media's dielectric function at frequencies below $\approx3\,$THz.
