Designing and building the largest radio telescope

Radio telescopes are not very different in their operation compared to optical telescopes: the resolution or detail sharpness of the observation depends on the opening or diameter of the telescope and on the wavelength. For observation on the 21 cm hydrogen line, Jan Oort wanted a radio telescope with a dish diameter of at least 100 wavelengths. He thought of a mirror of about 25 meters in diameter, based on the telescope of Grote Reber. At a wavelength of 21 centimeters, such a radio telescope can see details in the sky of about 0.5 degrees. That is an angle at the sky as big as the Sun or the Moon. The Würzburg antenna in Kootwijk could only observe details up to about 2 degrees.

As a result of the Dutch Milky Way research in Kootwijk and the international appreciation for this, money became available to build a large rotating 25 meter radio telescope. In 1954, the construction of the (popularly said) ‘chicken wire’ telescope began. Principals were the Netherlands Organization for Pure Scientific Research (now NWO) and the Netherlands Foundation for Radio Astronomy (NFRA, now ASTRON).

Under the supervision of engineer Ben Hooghoudt, the following companies were involved in designing and building the radio telescope:

  • design and realization of the 25 meter telescope: Werkspoor, department Bruggenbouw (Amsterdam);
  • design and realization of the electrical installation: Heemaf (Hengelo);
  • design of the foundation: Langhout engineers and architects office (Amsterdam);
  • realization of the foundation: Amsterdam Ballast Mij (Amsterdam);
  • design and realization of the mechanical-electrical coordinate transformer: Metaalbedrijf Rademakers (Rotterdam);
  • design and realization of the electronic control of the movement mechanism: NFRA with collaboration of the Royal Marine Laboratory Electronic Developments (Oegstgeest), Philips Physics Laboratory (Eindhoven) and PTT Dr. Neher Laboratory (Leidschendam);
  • design of the service building and house: Architectural office De Vlaming (Amsterdam);
  • realization of the service building and house: Vuurboom and Zn (Valthermond).

On April 17, 1956, Queen Juliana inaugurated the Dwingeloo Radio Telescope – then the largest in the world – with a symbolic push on a button.

The Construction of a Radio Telescope

Herman Kleibrink’s documentary film from 1957 (in Dutch).