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Paper: Pole STAR: An 810 GHz Array Receiver for AST/RO
Volume: 217, Imaging at Radio Through Submillimeter Wavelengths
Page: 48
Authors: Groppi, C.; Walker, C.; Hungerford, A.; Kulesa, C.; Jacobs, K.; Kooi, J.
Abstract: We are constructing a 4-channel receiver at 810 GHz for use on the Antarctic Submillimeter Telescope and Remote Observatory located at the South Pole (AST/RO). The 810 GHz mixers and junctions for the array are being provided by KOSMA. The mixers are housed in a hybrid cryostat located in a warm Coude' room just below the 1.7 m telescope. A pair of parabolic mirrors will be used to reimage the telescope's focal plane through a Martin-Puplett LO diplexer onto a 2x2 array of lenses. The lenses efficiently couple the telescope to each mixer's corrugated feedhorn. The SIS junction is matched to the waveguide by an on-chip tuner and a single, fixed backshort. The 1-2 GHz IF output of each mixer is fed into a low-noise, balanced, HEMT amplifier. All bias signals are provided by a computer controlled bias system, which is fully optically isolated from the control computer. This system provides automated adjustment and optimization of bias levels with web based monitoring. The IF outputs are further processed at room temperature and fed into a 4-channel array AOS constructed by KOSMA. A Gunn oscillator (J. Carlstrom) and multiplier (Erickson & Narayanan) are used to drive the array.
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