Parametric amplification in Josephson tunnel junction arrays at 33 GHz

Progress on the development of a low-noise superconducting parametric amplifier operated at liquid helium temperatures and designed for practical use with a radio telescope at 33 GHz is reported. Series arrays of small Pb - Pb oxide - Pb tunnel junctions (\sim 20 \mum × 20 μm) are coupled in a microstrip configuration and the Josephson device is operated as a reflection-type amplifier in the doubly degenerate mode. Various practical considerations in using such a devise on a telescope are reviewed. In preliminary experiments, gains of greater than 13 dB have been observed near 33 GHz.