Measurements of the complex permittivity at 107.3 GHz ofn‐type silicon specimens in the 5–50 &OHgr; cm resistivity range were made using a free space reflection/transmission technique. Reflectance measurements on specimens in the 0.004–5 &OHgr; cm range were obtained. All measurements were compared with a single relaxation time Drude model and a more complete model that was developed which includes Fermi–Dirac statistics and energy dependent lattice and impurity scattering. Although the Drude model was found to reliably predict the complex permittivity ofn‐type silicon over a specified range of resistivity, it has limitations which are discussed.