Integrated receiving structure comprising complementary spiral antenna and tuned parallel biased SIS array

摘要

A type of superconducting receiving element comprising a complementary spiral antenna and a series-parallel superconductor-insulator-superconductor (SIS) array with individual tuning of each SIS junction has been designed, fabricated, and experimentally studied. The array was designed for the 80-160 GHz waveband and consists of five SIS junctions, each with a 1.5- mu /sup 2/ area, six inductive short-ended slotlines, and two decoupling capacitances. The effective direct detector bandwidth of this structure with a quantum efficiency equalling unity has been estimated to be as wide as 70 GHz. The noise temperature of the heterodyne mixer has been measured in a three-lens Gaussian beam guide by means of the hot/cold load method, yielding a receiver DSB noise temperature of 80 K. The intermediate-frequency (IF) mixer port load bandwidth and the effect of thermal background radiation on the I-V curve and the saturation of the SIS mixer have been studied.