Doc Ewen: The Horn, HI, and Other Events in US Radio Astronomy

Slide 23: Microwave and Millimeter Wave Applications in the 1970s and 1980s

Sketch of signal paths in GOMUX from input to each of the eight receivers. A confocal system requires successive elements which focus one beam waist to another. Usually these elements are biconvex lenses, the reflective analog of which are ellipsoidal mirrors. Mirrors were chosen over lenses because of the ohmic and reflective losses of lenses would add several dB of loss to each band. Solid ellipsoidal mirrors are used in the input chain to direct the beam down to the optics table from the Cassegrain antenna. An additional solid ellipsoidal mirror is used in the GOMUX, at the 40° bend between the wire grid and band 8, to fold the beam and contain the size of the GOMUX. Credit: Photo and diagram courtesy of Doc Ewen.
Slide 24