The Committee on Radio Astronomy Frequencies (CRAF) is a committee of
the European Science Foundation (ESF).
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 |
| Belgium | Humain | No well-defined radio quiet zone. A general coordination area with a radius of ~2-3 km exists around the radio astronomy station | The coordination area has been established by the local authorities |
| Czech Republic | Ondrejov | 0.5 - 1.0 km | This zone and a coordination area of ~15 km diameter aound the radio astronomy station have been established by the local authorities |
| Finland | Metsähovi | about 1 km | The radio quiet zone has been established in consultation with the Finnish national regulatory authority |
| France | Bordeaux | Each radio astronomy station in France is registered as radio quiet zone. However, no real well-defined radio quiet zone or coordination area | All applications for licenses pass through the Commission des Sites et Servitudes in which the radio astronomy service has a representative and through the Commission d'Assignation des Fréquences in which the radio astronomy service is also represented. This representative can object to any application and after the process of evaluation of the application, a coordination takes place. If no agreement is possible, the Agence National des Fréquences will decide the case. The procedure to create a quiet zone is very complicated. |
| Nançay | Each radio astronomy station in France is registered as radio quiet zone. However, no real well-defined radio quiet zone or coordination area. It is not allowed to install a transmitter within a few km from each of the radio astronomy telescopes | All applications for licenses pass through the Commission des Sites et Servitudes in which the radio astronomy service has a representative and through the Commission d'Assignation des Fréquences in which the radio astronomy service is also represented. This representative can object to any application and after the process of evaluation of the application, a coordination takes place. If no agreement is possible, the Agence National des Fréquences will decide the case. The procedure to create a quiet zone is very complicated. | |
| Plateau de Bure | 3 km radius. | All applications for licenses pass through the Commission des Sites et Servitudes in which the radio astronomy service has a representative and through the Commission d'Assignation des Fréquences in which the radio astronomy service is also represented. This representative can object to any application and after the process of evaluation of the application, a coordination takes place. If no agreement is possible, the Agence National des Fréquences will decide the case. The procedure to create a quiet zone is very complicated. In practice all issues are settled by coordination with the regulatory authority. | |
| Germany | Effelsberg | No well-defined radio quiet zone or coordination area | occasional coordination accomplished with local administration |
| Tremsdorf | No well-defined radio quiet zone or coordination area | occasional coordination accomplished with local administration | |
| Wettzell | No well-defined radio quiet zone or coordination area | occasional coordination accomplished with local administration | |
| Hungary | Penc | about 2 km radius | Any new construction within the radio quiet zone has to be authorized by the local administration with the consent of the Institute for Geodesy, Cartography and Remote Sensing |
| Italy | Medicina | 2 km radius | The zone has been established by the Medicina Municipality |
| Noto | no regulatory quiet zone since station is surrounded by hills | ||
| Sardinia | station under construction: no quiet zone defined yet | ||
| Latvia | Riga | No well-defined radio quiet zone or coordination area | Issue under discussion with Latvian administration |
| the Netherlands | Dwingeloo | 1-2 km radius | The radio quiet zone has been established by the regional administration in consultation with the Dutch Radiocommunication Agency |
| Westerbork | about 2 km | The radio quiet zone has been established by the regional administration in consultation with the Dutch Radiocommunication Agency | |
| Poland | Kraków | No well-defined radio quiet zone or coordination area | |
| Torun | As yet no radio quiet zone. However, as a function of distance (up to 50 km) construction of buildings and installations which may possibly cause harmful interference is regulated | Arrangments for the regulation zone are established by the local authorities | |
| Portugal | Espiunca | No well-defined radio quiet zone or coordination area | Portuguese law foresees the installation of radio quite zones but implementation is currently subject to discussions between the Portuguese national administration and the Univerity of Porto |
| Russia | Badary | No well-defined radio quiet zone or coordination area | In specific cases coordination with radio astronomy station by Russian administration |
| Dmitrov | No well-defined radio quiet zone or coordination area | In specific cases coordination with radio astronomy station by Russian administration | |
| Kalyazin | No well-defined radio quiet zone or coordination area | In specific cases coordination with radio astronomy station by Russian administration | |
| Medveziy Ozera | No well-defined radio quiet zone or coordination area | In specific cases coordination with radio astronomy station by Russian administration | |
| Puschino | No well-defined radio quiet zone or coordination area | In specific cases coordination with radio astronomy station by Russian administration | |
| Svetloe | No well-defined radio quiet zone or coordination area | In specific cases coordination with radio astronomy station by Russian administration | |
| Zelenchukskaya | No well-defined radio quiet zone or coordination area | In specific cases coordination with radio astronomy station by Russian administration | |
| Zimenky | No well-defined radio quiet zone or coordination area | In specific cases coordination with radio astronomy station by Russian administration | |
| Spain | Pico Veleta | A section in the international treaty setting up the observatory engages the Spanish administration to protect the quality of the site. | |
| Sweden | Onsala | complicated function of azimuth. | The radio quiet zone has been defined by national law approved by the Swedish Parliament |
| Switzerland | Bleien (Zürich) | No well-defined radio quiet zone or coordination area | Issue still under discussion with Regulatory Authority |
| Turkey | |||
| United Kingdom | Cambridge | 0.5-1 km | Arrangement established by Radiocommunications Agency |
| Jodrell Bank | 0.5-1 km | Arrangement between University of Manchester and local administrations | |
| sites of the Multi-Element Radio-Linked Interferometer Network, MERLIN | 0.1 km | Regulatory protection through the Radiocommunications Agency |
Note:
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).