A microwave-biased millimeter- and submillimeter- wave detector using InSb

A high-purity n-type indium antimonide sample mounted in a reentrant cavity and cooled to 4.2°K was operated as a millimeter-wave detector. The scheme utilizes a downconversion process and free-carrier absorption is the mechanism responsible for the detection process. Power applied at the millimeter-wave frequency causes a change in the material conductivity which in turn causes a change in the -band power absorption; cavity perturbation techniques are used to analyze the scheme. The detector was operated successfully at frequencies between 35 and 150 GHz with no long wavelength or short wavelength cutoff observed. The scheme offers a fast highly sensitive and rugged detector with low conversion loss.