The Front-End of the NOEMA Interferometer

The IRAM Plateau de Bure Interferometer (PdBI) is being upgraded to a new powerful millimeter-wave radio astronomy facility called the NOrthern Extended Millimeter Array (NOEMA) which will double the number of the 15-m diameter antennas from six to 12. All antennas will be equipped with a new generation of dual-polarization Front-End covering the 72-373-GHz frequency range with four independent receivers integrated into a single cryostat. All receivers utilize sideband separating (2SB) superconductor-insulator-superconductor (SIS) mixers, each of which delivers two ~7.7-GHz-wide intermediate frequency (IF) outputs per polarization channel, thus increasing the total IF bandwidth which can be processed with a single setting of the interferometer from 8 GHz (2 ×4 GHz delivered by the existing PdBI Front-End) to ~31 GHz (4 × ~ 7.7 GHz delivered by the NOEMA Front-End). The first of the new NOEMA antennas (Ant. 7) has recently been completed and the first NOEMA Front-End successfully developed and installed in it. For the coming years, our goal is to upgrade all of the Front-Ends currently installed on the six existing PdBI antennas to the new NOEMA standard and to build six additional ones (plus one spare) for the new NOEMA antennas. In this paper, we describe the design, fabrication, and assembly of the Front-End we have developed for NOEMA Antenna 7. The instrument has state-of-the-art performance and sets a new standard in the post-ALMA generation technology.