G. Delange et al., CHARACTERIZATION OF A 680-760 GHZ SIS WAVE-GUIDE MIXER, International journal of infrared and millimeter waves, 17(1), 1996, pp. 61-77
A heterodyne waveguide receiver employing 1 mu m(2) Nb superconducting
tunnel junctions with on chip integrated tuning structures is charact
erized from 680-760 GHz. Several different types of integrated tuning
structures are investigated. Lowest DSB receiver noise temperatures of
310 K at 709 GHz and 400 K at 720 GHz are measured. Analysis of the d
ata shows that the loss of the superconducting tuning structures has a
major influence on the overall receiver performance. A 25% reduction
in receiver noise temperature is observed if the mixer is cooled from
4.2 K to 2 K, which we attribute to the reduced loss of the supercondu
cting microstrip lines at lower temperatures. The calculated performan
ce of the different tuning structures is shown to be in good agreement
with the actual receiver noise measurements.