PT Unknown AU Semenov, AD Hübers, HW Schubert, J Gol'tsman, GN Elantiev, AI Voronov, BM Gershenzon, EM TI Frequency dependent noise temperature of the lattice cooled hot-electron terahertz mixer SE Proc. 11[super:th] Int. Symp. Space Terahertz Technol. PY 2000 BP 39 EP 48 DE NbN HEB mixers AB We present the measurements and the theoretical model on the frequency dependent noise temperature of a lattice cooled hot electron bolometer (HEB) mixer in the terahertz frequency range. The experimentally observed increase of the noise temperature with frequency is a cumulative effect of the non-uniform distribution of the high frequency current in the bolometer and the charge imbalance, which occurs near the edges of the normal domain and contacts with normal metal. In addition, we present experimental results which show that the noise temperature of a HEB mixer can be reduced by about 30% due to a Parylene antireflection coating on the Silicon hyperhemispheric lens. ER