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Elektromagnetische Felder

Radar systems

Radar systems are used in a large variety of places and a wide range of applications, for example

  • in civil and military air surveillance,
  • on ships,
  • in weather observations,
  • in road traffic monitoring,
  • in vehicle driver assistance systems, such as adaptive cruise control and emergency brake assist,
  • in level measurement systems for liquid tanks or bulk storage silos.

The frequencies used range from 1 to 100 gigahertz (see table Sources of high-frequency fields). The transmitter powers depend on the particular application and may vary from a few milliwatts up to the megawatt range (pulse power) for wide-range radar systems.

Exposure from radar systems

Air surveillance and weather observations

Radar systems used for air surveillance and weather observations predominantly radiate their energy upwards into the airspace. The exposure from the fields in the vicinity of radars in areas of public access is low. This has been demonstrated, for instance, by measurements carried out at weather surveillance radar sites in Great Britain. Adverse effects to the public are not expected.

Radar systems on ships

Radar systems on ships do not present a hazard to the general public - for example in the vicinity of a waterway bank.

Speed control radars

The exposure from radar devices for traffic speed control amounts to only a fraction of the limits recommended for the protection of human health. At working distance, they are harmless to the health of the operating personnel as well as to public health.

Driver assistance systems in motor vehicles

Compared to other applications, relatively little information on radar devices for driver assistance systems in motor vehicles is available at the moment. The focusing of the radiated power and the shielding effect of the metal vehicle body ensure that the individuals in the vehicle are practically not exposed. As radiated powers are low and the devices are usually inactive when the vehicle is stationary, a health risk to other road users or pedestrians is not expected.

Legal regulations

Stationary radar installations are considered stationary radio installations as defined by the Ordinance concerning the Controls for the Limitation of Electromagnetic Fields (BEMFV). A valid site certificate issued by the Federal Network Agency is required for operating installations at locations with an installed radiated power of 10 watts (assuming omnidirectional homogeneous emission) or more. This especially affects radar systems for air surveillance and weather observations. The site certification procedure is laid down in the "BEMFV" of 20 August 2002. The ordinance was last modified on 14 August 2013.

In the site certificate, the Federal Network Agency indicates an individual safety distance for the relevant location. Outside the safety distance, the limit values set in the 26th Ordinance implementing the Federal Immission Control Act (26. BlmSchV) are complied with. When determining the safety distance, the Federal Network Agency takes stationary radio installations in the frequency range from 9 kilohertz to 300 gigahertz that are already installed at the location and in its vicinity into account. Newly planned installations are considered, provided they are known.

Stray X-rays may emanate from high-power radar transmitters

Stray X-rays may also be produced within high-power radar transmitters - depending on their design - as an unwanted side effect (see Final report of the Radar Commission). However, a health-relevant exposure from X-radiation cannot occur when safety regulations are complied with.

State of 2018.11.12

© Bundesamt für Strahlenschutz