Instrumentation for heterodyne mm-wave astronomy

Abstract
This contribution is intended to provide a brief overview of mm-wave heterodyne instrumentation, of the main categories of components, and of the challenges for continued development.
The scope of this overview includes, beyond the receiver itself, the antenna and the atmosphere, that jointly contribute to the achievable sensitivity. It does not include spectrometers, whose technology is not specific to the mm-wave domain, and with which a simple interface (power level, bandwidth) can be defined.
This review reports the progress of the community of engineers and scientists devoting themselves to the improvement of mm-wave heterodyne instrumentation; in the course of its preparation, I have benefitted from the experience accumulated during years of collaboration with that community at large, and with my colleagues at IRAM in particular.