MASTER: three heterodyne receivers for Millimetre and Submillimetre-wave astronomy

• Main Authors: BATTISTELLI, Elia Stefano, ANDREONE D, BOELLA G, BRUNETTI L, CAVALIERE F, DE PETRIS, Marco, GERVASI M, LACQUANITI V, NATALE V, PASSERINI A, SIRONI G, STENI R, THORPE J. R, TOFANI G, ZANNONI M.
• Other Authors: Battistelli, Elia Stefano, Andreone, D, Boella, G, Brunetti, L, Cavaliere, F, Gervasi, M, Lacquaniti, V, Natale, V, Passerini, A, Sironi, G, Steni, R, Thorpe, J. R., Tofani, G, Zannoni, M.
• Format: Conference Object
• Language: English
• Published: 2001
• Subjects: heterodyne receivers; mm astronomy; radiometers; Antarctic; Antarc*
• Online Access: http://hdl.handle.net/11573/324964

We describe a system of three heterodyne receivers for astrophysical observation at $94GHz$, $225GHz$ and $345GHz$ through the atmospheric windows available at dry, high altitude sites (Italian Alps, Antarctic Plateau). Three $SIS$ mixers, fed by geometrically scaled corrugated horns, oriented in the same direction, form the core of our system. The four beams (HPBWs $sim 7^{circ}$) are optimized for matching the focus of the $MITO$ or sub-mm wave telescopes. The intermediate frequency ($IF$) signal produced by each mixer is $1.5GHz$, with an instantaneous bandwidth of $pm0.4GHz$. Each receiver is mechanically tunable over a total bandwidth of $pm1GHz$ at $94GHz$, $pm2.5GHz$ at $225GHz$ and $pm4GHz$ at $345GHz$. The $SIS$ mixer and the first $IF$ amplifier are cooled at $4K$ and the expected noise temperature of the system are between $100K$ and $170K$. The local oscillator and cold load reference signals are injected into the horns by a diplexer and mirror combinations. Rotation of a mirror modulates the system output for synchronous detection. An acousto-optical system at the $IF$ output is used for spectroscopic observation.