Receiver technology for terahertz astronomy

For astronomical applications, the lowest noise and highest sensitivity is usually required, often necessitating the use of cooled detectors. For molecular line astronomy, high spectral resolution is also needed. Receiver systems for submillimetre astronomy can be broadly grouped into three main categories: direct (bolometric) detector, Schottky barrier diode mixer and superconducting mixer receivers. The characteristics of each are considered. The author goes on to describe an 800-900 GHz heterodyne receiver