Radio quiet zones around observatories

Usually, a radio quiet zone has been established around a radio astronomy station. Within such an area motorized traffic is severely restricted or forbidden, and there may be several severe restrictions on the use of electronic equipment and on the existences of e.g. factories, buildings and construction works within that area: i.e. radio quiet means really quiet.

In addition, it is common practice that for specific electronic equipment, such as for mobile earth stations, administrations determine separation distances around radio astronomy stations. These separation distances are usually larger than the extent of the generic radio quiet zone. These specific distances depend on the transmission characteristics of this equipment and on the frequency on which it operates.

In the different European countries the situation for the radio quiet zones is as follows:

Country Radio Astronomy Observatory Separation distance from radio astronomy station Regulatory Process
Finland Metsähovi About 1 km radius The radio quiet zone has been established in consultation with the Finnish national regulatory authority
France Nançay 1 – 3 km Radio quiet zone established by the French national protection zone law since December 2010.

RQZ distance is one kilometre for electromagnetic compatibility with all devices and three kilometre for compatibility with emitters.

Outside this RQZ, in the framework of the National Frequency Agency and the National Table of Frequency Regulation, the radioastronomy service may oppose the modification or installation of any transmitter which does not agree for the protection of a radio astronomy station.

Plateau de Bure 1 – 3 km See above
Ireland Birr No defined radio quiet zone
Italy Medicina

1.5 / 3 / 10 km radius

The three protected zones have been established by the Medicina Municipality in the building regulatory plan respectively for civil buildings (1.5 km), buildings with technological equipments (3 km) and power lines >100 KV (10 km). Any new installation in these areas requires the approval of the Observatory

No well-defined radio quiet zone or coordination area.


15 km

Although no real radio quiet zone or coordination area is defined by regional regulation, since 2016 the Observatory can express opinion with a binding technical prescriptions, if a request for a new radio transmitter installation (or an upgrading of existing one) is submitted to the local municipalities office within an area of about 15 km around the telescope
Spain Yebes Observatory

> 1 km

Protected by a national law (
Pico Veleta

> 1 km

See above

Robledo de Chavela

> 1 km

          See above

> 1 km

         See above
Sweden Onsala

No defined radio quiet zone

Act on Protection of Research Sensitive to Disturbance
Ukraine All observatories

No defined radio quiet zone


The separation distance depends on the characteristics of the radio astronomy station (whether it is a single dish instrument, an interferometer or participating in Very Long Baseline Interferometry), the frequencies used and the research priorities (spectral line or continuum emission).

Committee on Radio Astronomy Frequencies