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 |
| Noto |
No well-defined radio quiet zone or coordination area. |
||
| Sardinia |
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 (https://www.boe.es/buscar/pdf/2014/BOE-A-2014-4950-consolidado.pdf) |
| Pico Veleta |
> 1 km |
See above |
|
| Robledo de Chavela |
> 1 km |
See above | |
| Cebreros |
> 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 |
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).