Hochfrequenzverhalten gekoppelter und ungekoppelter Josephson-Kontakte auf der Basis von Hochtemperatur-Supraleitern

The behaviour of HTS Josephson junctions have been investigated experimentally and theoretically with the aim to THz-applications. In the first part the behaviour of intrinsic Josephson junction stacks are measured and the possibility of phase locking is discussed by the theoretical analysis of two different shunt technologies depending on the parameter spread of the junction (up to 15%) and the shunt parameters. In the second part the mixing properties, especially noise, conversion efficiency and saturation behaviour, of HTS bicrystal Josephson junctions as wave guide mixers for 115 and 345 GHz have been investigated. The lowest noise temperatures have been obtained when the E-plane and the backshort tuner generate a resonant coupling to the Josephson junction. At 20 K operating temperature a lowest DSB mixer noise temperature of about 1000 K and a mixer conversion efficiency of ?0.8 dB was obtained with a 345 GHz mixer.