PT Unknown AU Mann, CM Matheson, DN Ellison, BN Oldfield, ML Moyna, BP Spencer, JJ Wilsher, DS Maddison, BJ TI On the design and measurement of a 2.5 THz waveguide mixer SE Proc. 9[super:th] Int. Symp. Space Terahertz Technol. PY 1998 BP 161 ER