Wideband 67-116 GHz cryogenic receiver development for ALMA Band 2. (arXiv:1812.03575v1 [astro-ph.IM])

Wideband 67-116 GHz cryogenic receiver development for ALMA Band 2. (arXiv:1812.03575v1 [astro-ph.IM])
<a href="http://arxiv.org/find/astro-ph/1/au:+Yagoubov_P/0/1/0/all/0/1">P. Yagoubov</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Mroczkowski_T/0/1/0/all/0/1">T. Mroczkowski</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Testi_L/0/1/0/all/0/1">L. Testi</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Breuck_C/0/1/0/all/0/1">C. De Breuck</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Gonzalez_A/0/1/0/all/0/1">A. Gonzalez</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Kaneko_K/0/1/0/all/0/1">K. Kaneko</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Uzawa_Y/0/1/0/all/0/1">Y. Uzawa</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Molina_R/0/1/0/all/0/1">R. Molina</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Tapia_V/0/1/0/all/0/1">V. Tapia</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Reyes_N/0/1/0/all/0/1">N. Reyes</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Mena_P/0/1/0/all/0/1">P. Mena</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Beltran_M/0/1/0/all/0/1">M. Beltran</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Nesti_R/0/1/0/all/0/1">R. Nesti</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Cuttaia_F/0/1/0/all/0/1">F. Cuttaia</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Ricciardi_S/0/1/0/all/0/1">S. Ricciardi</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Sandri_M/0/1/0/all/0/1">M. Sandri</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Terenzi_L/0/1/0/all/0/1">L. Terenzi</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Villa_F/0/1/0/all/0/1">F. Villa</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Murk_A/0/1/0/all/0/1">A. Murk</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Kotiranta_M/0/1/0/all/0/1">M. Kotiranta</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+McGenn_W/0/1/0/all/0/1">W. McGenn</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Cuadrado_Calle_D/0/1/0/all/0/1">D. Cuadrado-Calle</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Fuller_G/0/1/0/all/0/1">G. A. Fuller</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+George_D/0/1/0/all/0/1">D. George</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Gallego_J/0/1/0/all/0/1">J.-D. Gallego</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Lapkin_I/0/1/0/all/0/1">I. Lapkin</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Fredrixon_M/0/1/0/all/0/1">M. Fredrixon</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Belitsky_V/0/1/0/all/0/1">V. Belitsky</a>

The Atacama Large Millimeter/sub-millimeter Array (ALMA) is already
revolutionising our understanding of the Universe. However, ALMA is not yet
equipped with all of its originally planned receiver bands, which will allow it
to observe over the full range of frequencies from 35-950 GHz accessible
through the Earth’s atmosphere. In particular Band 2 (67-90 GHz) has not yet
been approved for construction. Recent technological developments in cryogenic
monolithic microwave integrated circuit (MMIC) high electron mobility
transistor (HEMT) amplifier and orthomode transducer (OMT) design provide an
opportunity to extend the originally planned on-sky bandwidth, combining ALMA
Bands 2 and 3 into one receiver cartridge covering 67-116 GHz.

The IF band definition for the ALMA project took place two decades ago, when
8 GHz of on-sky bandwidth per polarisation channel was an ambitious goal. The
new receiver design we present here allows the opportunity to expand ALMA’s
wideband capabilities, anticipating future upgrades across the entire
observatory. Expanding ALMA’s instantaneous bandwidth is a high priority, and
provides a number of observational advantages, including lower noise in
continuum observations, the ability to probe larger portions of an astronomical
spectrum for, e.g., widely spaced molecular transitions, and the ability to
scan efficiently in frequency space to perform surveys where the redshift or
chemical complexity of the object is not known a priori. Wider IF bandwidth
also reduces uncertainties in calibration and continuum subtraction that might
otherwise compromise science objectives.

Here we provide an overview of the component development and overall design
for this wideband 67-116 GHz cryogenic receiver cartridge, designed to operate
from the Band 2 receiver cartridge slot in the current ALMA front end receiver
cryostat.

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