9414468 Walker Obstacles encountered in designing low noise, high efficiency, heterodyne receivers and local oscillator (LO) sources at submillimeter wavelengths include the quality and cost of waveguide structures. At wavelengths shorter than 400 um, rectangular waveguide structures, feedhorns, and backshorts become prohibitively difficult to fabricate using standard machining techniques. Silicon micro-machining techniques will be used to fabricate high quality waveguide structures and components for use at submillimeter wavelengths. The objective of this project is to develop the technology necessary to construct high efficiency, low-cost heterodyne array receivers and signal sources which operate into the terahertz frequency range. Silicon laser etching will be demonstrated by constructing and testing silicon micromachined waveguide mixer arrays for use at 492 and 850 GHz. These arrays will be built in collaboration with the Max Planck Institute for Radio Astronomy. ***