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The radiometer is being developed for Bolshoi Azimuthal Telescope (BTA) of Special Astrophysical Observatory of Russian Academy of Sciences for observations within the little-developed 0.13-0.38 THz (2.3-0.8 mm wavelength) range using atmospheric transmission windows. We assume that the radiometer can be used with other radio- and optical telescopes as well as at higher frequencies of the terahertz band. The main functional parts of the radiometer are transition edge sensors (TES bolometers) integrated within an antenna array, an optical system coupling the antenna to a telescope beam, a and a cryogenic system.

This paper studies superconductor insulator superconductor (SIS) mixers for ALMA Band-10 project. The possible scheme of the ALMA Band-10 cartridge with balanced lens-antenna mixers is presented. The new balanced full-height waveguide SIS mixer comprises two equal mixer chips fabricated on quartz substrates. Each chip contains an RF circuit with hybrid twin-SIS junction NbTiN/Nb-AlOx-Nb/Al. The preliminary experimental study of Band-10 receiver with a double-slot antenna SIS mixer mounted with a 10-mm immersion silicon lens is done to define an optimum layout of the tuning circuit and a combination of materials leading to the best performance of the SIS mixer.

In this work the output noise calibration of cryogenically cooled low noise SIS mixers, direct detectors and IF amplifiers by means of SIS noise source was studied experimentally. Applying LO power sufficient to linearize IV curve of SIS one may vary noise temperature from 4,2 to 100 K by changing bias current. Shot noise in series arrays of SIS junctions differs from noise in single junction.