Focal-plane array (radio astronomy)

Focal-plane arrays (FPAs) are widely used in radio astronomy. FPAs are arrays of receivers placed at the focus of the optical system in a radio-telescope. The optical system may be a reflector or a lens. Traditional radio-telescopes have only one receiver at the focus of the telescope, but radio-telescopes are now starting to be equipped with focal plane arrays, which are of three different types: multi-beam feed arrays, bolometer arrays, and the experimental phased-array feeds.