Refractory material SIS junction structures

Niobium based SIS junction structures for microwave receiving devices were investigated. The possibility of the mixing efficiency improving for Nb-Al
2
O
3
-Nb junctions with a negative resistance on I-V curve near the gap voltage has been demonstrated. Comparative microwave investigation of the parallel and series DC biased arrays shows the advantage of the first one. SIS junction capacitance has been compensated with microstrip or lumped elements at the signal frequency. Such compensated structures were investigated at frequencies 38 and 76 GHz both in waveguide and quasioptic systems.