Built in 1937 in Illinois by the astronomer Grote Reber, it was the first purpose-built parabolic radio telescope.

It consists of a parabolic reflector composed of 72 radial rafters and covered in 26 gauge iron sheeting with a focal length of 20 feet (6.1 m).

It is 31 feet 5 inches (9.58 m) in diameter and is mounted on arched rails positioned on railroad wheels, allowing its angle of elevation to be controlled.

[3] The telescope was built by Reber in his back yard in Wheaton, Illinois, in 1937, following up on the research of Karl Jansky, the discoverer in 1933 of radio waves emanating from the Milky Way.

Reber sold the telescope to the US National Bureau of Standards and it was moved to Sterling, Virginia.