Abstract
The Josephson junction radiator (JJR) is a thin-film superconducting device that converts DC voltage into coherent millimeter-wave (mm-wave) radiation. The source is frequency tunable, instantaneously narrow-band, compact, lightweight, has no moving parts, and may share the same cryogenic and vacuum space as the device under test. With these favorable characteristics, the JJR may find use as a general purpose calibration tool for low-temperature mm-wave detectors. We show that the JJR unambiguously emits mm-wave radiation and couples to a mm-wave detector. We use the JJR to determine the spectral response of a superconducting mm-wave detector that operates in two large frequency passbands centered at 150 and 220 GHz. A comparison to measurements with a conventional Fourier transform spectrometer is presented, and the use of the JJR as a precision spectral calibration tool is discussed.