Performance Of A Single Ended Schottky Diode Mixer At 345 GHZ As Low Noise Mixer And Frequency Doubler For 690 GHz

The first part of this paper describes the design and construction of a low noise Schottky diode waveguide mixer, operating in the 320-370 GHz band. The mixer incorporates a fundamental mode waveguide, a broadband coaxial RF-structure and a contacting tunable backshort. Construction details of the mixer will be given, as well as noise temperature and conversion loss measurements for a room temperature device. The influence of the whisker length on the mixer performance will be described. The possibility of using the same mixer design for a 490 GHz mixer will also be considered. Some preliminary measurement results will be presented. The second part of this paper describes a measurement setup for investigation of the performance of a mixer as frequency doubler with 690 GHz output frequency. Results of measurements of output power at 690 GHz will be presented, showing the capability of a single ended Schottky mixer to produce adequate local oscillator power to drive e.g. an InSb-bolometer.