PT Unknown AU Kroug, M Cherednichenko, S Choumas, M Merkel, H Kollberg, E Hübers, H Richter, H Loudkov, D Voronov, B Gol'Tsman, G TI HEB quasi-optical heterodyne receiver for THz frequencies SE Proc. 12[super:th] Int. Symp. Space Terahertz Technol. PY 2001 BP 244 EP 252 DE HEB mixer; NbN; MgO; conversion gain bandwidth; noise temperature PI San Diego, CA, USA ER