Speaker
Dr
Richard Bradley
(NRAO NTC)
Description
Details of our work on evaluating commercial phase shifters for cavity impedance matching at cryogenic temperatures are presented. A brief overview of the circuitry is given followed by information on two candidate phase shifters – one surface mount and one packaged. The test and modelling procedures for both bench and cryogenic measurements are outlined. Initial cryogenic measurements indicated no variation in phase with bias voltage – this problem was traced to the use silicon varactors in these commercial units. The circuit topologies were studied and GaAs varactor replacements are being ordered.
Primary author
Dr
Richard Bradley
(NRAO NTC)