PT Journal
AU Meledin D.
   Desmaris V.
   Ferm S.-E.
   Fredrixon M.
   Henke D.
   Lapkin I.
   Nyström O.
   Pantaleev M.
   Pavolotsky A.
   Strandberg M.
   Sundin E.
   Belitsky V.
TI APEX Band T2: A 1.25 – 1.39 THz Waveguide  Balanced HEB Receiver
PY 2008
BP 181
EP 185
AB A waveguide 1.25–1.39 THz Hot Electron Bolometer (HEB) balanced receiver was successfully developed, characterized and installed at the Atacama Pathfinder EXperiment (APEX) telescope. The receiver employs a quadrature balanced scheme using a waveguide 90-degree 3 dB RF hybrid, HEB mixers and a 180-degree IF hybrid. The HEB mixers are based on ultrathin NbN film deposited on crystalline quartz with a MgO buffer layer. Integrated into the multi-channel APEX facility receiver (SHeFI), the results presented here demonstrate exceptional performance; a receiver  noise temperature of 1000 K measured at the telescope at the center of the receiver IF band 2-4 GHz, and at an LO frequency of 1294 GHz. Stability of the receiver is fully in line with the SIS mixer bands of the SHeFI, and gives a spectroscopic Allan time of more than 200 s with a noise bandwidth of 1 MHz.
ER