Long wave transmitter

from Wikipedia, the free encyclopedia
Alexanderson antennas of the radio station Kalundborg of Danmarks Radio

A long-wave transmitter is a transmission system for electromagnetic waves with frequencies in the long-wave range , i.e. in the frequency range between 30  kHz and 300 kHz.

Long-wave transmitters are used to transmit time signals , broadcast radio coverage, the sending of weather reports from the DWD as radio telex or in fax format , the transmission of telegraphic messages or radio navigation . A narrow frequency band at 137 kHz is also available to amateur radio . The radio transmitters for long wave are operated in the frequency range between 148.5 kHz and 283.5 kHz with outputs from 10 to 2500 kilowatts. The first commercial transmitters were often pop-spark transmitters until the introduction of electron tubes in transmitter construction , later also extinguishing spark transmitters or machine transmitters .

The definition of the transmission frequencies used, the transmission power and whether and in what form directional radiation may be used was laid down in the 1974/75 Geneva Wave Plan , which came into force on November 23, 1978. Some intergovernmental coordination of this plan has now been carried out. In Germany, the Federal Network Agency issues the current frequency plan.

Transmitting antennas

The transmitter Droitwich the BBC , Power 500 kW

For long wavelengths of one to ten kilometers, correspondingly large and sometimes very high transmission antennas are required. Some transmission antennas of long-wave transmitters (e.g. the Konstantynów transmission mast with 646 m) were among the tallest structures on earth.

As transmission antennas for omnidirectional radiation , self-radiating transmission masts isolated from earth with base feed or earthed self-radiating transmission masts with top feed , sometimes also trap or T antennas, are used.

Arrangements of several self-radiating transmission masts are used for directional radiation . In addition, vertical traps mounted on earthed towers or masts , T-antennas , Alexanderson antennas or shield antennas , which are usually stretched between two towers or masts, which are usually isolated from earth, are also used.

For radio beacons ( NDB ), free-standing tubular masts that are only about ten meters high and isolated from the ground are usually used. Occasionally, arrangements with several masts are used, either to achieve a directional effect or to enlarge the area of near fading-free reception ( fading-reducing transmitting antenna ).

Occasionally, reference is made to "novel" antennas, as in the case of cross-field antennas . In principle, these are Tesla coils . As a transmitting antenna, however, due to extremely high losses, no significant radio coverage is to be expected from these.

From this point at the latest, a very precise distinction must be made between a transmitting and receiving antenna. Another, suggestive reason can be found under antenna technology . An exception would present their use in RFID solutions, which in the near field of work of the antenna with a range of a few tens of centimeters.

Long-wave transmitters for the transmission of telegraphic messages mostly use T-antennas or self-radiating transmission masts with roof capacity (shield antennas) suspended from masts or towers that are isolated from earth . A power of up to 100 kilowatts is used.

Use long-wave transmitters for radio navigation services if they are operated with high power like the Decca and LORAN-C , self-radiating transmission masts with roof capacity as a transmitting antenna. Long-wave transmitters for radio navigation services with low power such as NDBs mostly use small tubular masts insulated from the ground, which are hardly noticeable due to their height of only ten meters.

Well-known transmission systems

The transmitter Allouis of Radio France , power 2000 kW

Active LW transmitters

Broadcast:

Other:

Inactive LW transmission systems

Former LW transmission systems

Pictures of channels preserved in museums

See also

Web links

Commons : Longwave transmitter Europe 1  - Collection of images, videos and audio files
Wiktionary: long wave transmitter  - explanations of meanings, word origins, synonyms, translations

Individual evidence

  1. ↑ Радио и телевизия в Ихтиман - Предавател България. In: www.predavatel.com. Retrieved September 6, 2016 .
  2. ↑ a b c Deutschlandradio: press release, long wave shutdown: Deutschlandradio relies on modern distribution channels. November 28, 2014, accessed January 1, 2015 .