A 230-GHz Radiometer System Employing a Second-Harmonic Mixer (Short Papers)

A radiometer system for use in the lambda ~ 1.3 mm (v ~ 230 GHz) region has been constructed and used for radio astronomical observations. A second-harmonic mixer employing a single Schottky diode downconverts the incident power to an IF frequency of -1400 MHz. The measured double-sideband system noise temperature is 6000 K (noise figure = 13 dB) and the double-sideband mixer conversion loss is calculated to be 10 dB. The mixer is tunable over a range of at least 15 GHz.