Mediumwave transmitter Mainflingen
Encyclopedia
The Mediumwave transmitter Mainflingen (Mainflingen B) is a mediumwave
transmission facility south of the A3 motorway near Mainflingen
, Hesse
, Germany
. Mainflingen was the first mediumwave transmitter
for the radio station Deutschlandfunk
. It went into service in 1962 with a transmission power of 50 kW, on a frequency of 1538 kHz, at the upper end of the mediumwave band. This frequency has a bad groundwave propagation
and therefore a low range at daytime, but an excellent skywave
propagation with a long range at night.
In December 1962 the transmission power of Mainflingen was increased to 300 kW. Until 1967 its antenna was on the same site as the Mainflingen longwave transmitter
s. This resulted in interference problems, which made the desired further increase of transmission power impossible. A new transmitter, with a directional and an omnidirecional antenna
, was built in the mid-1960s on a site south of the A3, at a distance great enough from the longwave transmitters that even when using a power of 1000 kW, no greater interference problems would occur. This facility went into service on January 1, 1967.
The directional and the omnidirectional antennas were somewhat unusual for mediumwave broadcasting antennas. The omnidirectional antenna consisted of a ground-fed 142-metre-tall guyed mast, carrying a double conical cage antenna with a diameter of 64 metres. This construction allowed its usage for all mediumwave frequencies, and therefore also as backup antenna for Deutschlandfunk's mediumwave transmitters at other sites. The directional antenna consisted of two horizontal dipole
s which were mounted on 4.85-metre-tall guyed masts at a height of 75 metres, with a radiation maximum showing in northeast and southwest direction. As the omnidirectional antenna could not be used for the full available transmission power of 700 kW, in 1974 a 95-metre-tall guyed ground-fed mast radiator was built. A transmission power of 1050 kW was also possible by switching the third backup transmitter in parallel, but for economical reasons was never used. The transmitter was now run during the day with 700 kW and omnidirectional radiation, and at night with 350 kW and directional radiation, and was also used in the evenings for transmitting English-language programmes.
The introduction of the wave plan of Geneva
resulted in an increase of the transmission frequency from 1538 kHz to 1539 kHz. Mainflingen's daily operation mode was not affected. However, according to the wave plan, it was no longer allowed to use the double conical antenna as backup antenna for Deutschlandfunk's other mediumwave transmitters. The regulations of the wave plan of Geneva do not normally allow operation of backup transmitters more than 50 kilometres away from the standard site without special coordinative measures. This antenna was therefore dismantled in 1982.
After March 1, 1983 Deutschlandfunk was also broadcast at night using omnidirectional radiation, and the four masts of the directional antenna was dismantled afterwards. From April 1, 1988 the transmission power was reduced to 350 kW. Beside the bad groundwave propagation of the used frequency, broadcasts from the transmitter were only sufficiently well-received durin daytime, despite the high power output. This resulted in a shut-down of the transmitter on December 31, 1994, some years after the cancellation of foreign language transmissions.
As a replacement, Saarländischer Rundfunk
's Heusweiler transmitter was leased. It was first planned to demolish the Mainflingen facility, but on April 1, 1996 Evangeliums-Rundfunk (ERF), a religious broadcaster, which already hired transmission time at Trans World Radio restarted its operation.
Several disputes between Deutsche Telekom
and the Mainhausen
municipality occurred, as after the relaunch, problems with electromagnetic influence of electric devices were reported. Local residents were therefore opposed to continued use of the transmitter. In 1998 it was decided that the site could be used for mediumwave transmission and modernization of the facility started. First the old transmitter was replaced by a new, fully transistor
ized transmitter, which would be also able to operate in DRM
mode.
In order to allow a good night-time transmission without causing too many problems with electromagnetic influence, a cross-dipole antenna with a radiation maximum pointing vertically into the sky was built in early 2006. This antenna, which is one of the few applications of circular polarisation for broadcasting, is mounted on 5 guyed masts. The central mast of this antenna is grounded. It carries the feeder cables running to the dipole, while the masts at the edge are standing on insulators and grounded via inductance
s in such way that they radiate as low a frequency as possible. In this way, undesired parasitic radiations, which are the cause of electromagnetic influence, are suppressed. It is also interesting to know that the radiated wave must be right-hand polarized, otherwise the signal reflected on the ionosphere
would be 20 dB
less strong. In spring 2006 this new antenna went into service. It is used only for night-time transmissions, as the desired ionospheric reflection occurs only at night. During the day the old mast is used.
Mediumwave
Medium wave is the part of the medium frequency radio band used mainly for AM radio broadcasting. For Europe the MW band ranges from 526.5 kHz to 1606.5 kHz...
transmission facility south of the A3 motorway near Mainflingen
Mainflingen
Mainflingen is a small settlement of about 3800 inhabitants, a constituent community of the municipality Mainhausen in Hesse, Germany....
, Hesse
Hesse
Hesse or Hessia is both a cultural region of Germany and the name of an individual German state.* The cultural region of Hesse includes both the State of Hesse and the area known as Rhenish Hesse in the neighbouring Rhineland-Palatinate state...
, Germany
Germany
Germany , officially the Federal Republic of Germany , is a federal parliamentary republic in Europe. The country consists of 16 states while the capital and largest city is Berlin. Germany covers an area of 357,021 km2 and has a largely temperate seasonal climate...
. Mainflingen was the first mediumwave transmitter
Transmitter
In electronics and telecommunications a transmitter or radio transmitter is an electronic device which, with the aid of an antenna, produces radio waves. The transmitter itself generates a radio frequency alternating current, which is applied to the antenna. When excited by this alternating...
for the radio station Deutschlandfunk
Deutschlandfunk
Deutschlandfunk is a German public broadcasting radio station, broadcasting national news and current affairs.-History:Broadcasting in the Federal Republic of Germany is reserved under the Basic Law to the states. This means that all public broadcasting is regionalised...
. It went into service in 1962 with a transmission power of 50 kW, on a frequency of 1538 kHz, at the upper end of the mediumwave band. This frequency has a bad groundwave propagation
Radio propagation
Radio propagation is the behavior of radio waves when they are transmitted, or propagated from one point on the Earth to another, or into various parts of the atmosphere...
and therefore a low range at daytime, but an excellent skywave
Skywave
Skywave is the propagation of electromagnetic waves bent back to the Earth's surface by the ionosphere. As a result of skywave propagation, a broadcast signal from a distant AM broadcasting station at night, or from a shortwave radio station can sometimes be heard as clearly as local...
propagation with a long range at night.
In December 1962 the transmission power of Mainflingen was increased to 300 kW. Until 1967 its antenna was on the same site as the Mainflingen longwave transmitter
Mainflingen longwave transmitter
Mainflingen longwave transmitter is a large facility for commercial longwave transmissions at Mainflingen, Hesse, Germany, which was built in 1956. It uses several T- and triangle antennas, which are mounted on guyed masts of lattice steel, insulated against ground...
s. This resulted in interference problems, which made the desired further increase of transmission power impossible. A new transmitter, with a directional and an omnidirecional antenna
Antenna (radio)
An antenna is an electrical device which converts electric currents into radio waves, and vice versa. It is usually used with a radio transmitter or radio receiver...
, was built in the mid-1960s on a site south of the A3, at a distance great enough from the longwave transmitters that even when using a power of 1000 kW, no greater interference problems would occur. This facility went into service on January 1, 1967.
The directional and the omnidirectional antennas were somewhat unusual for mediumwave broadcasting antennas. The omnidirectional antenna consisted of a ground-fed 142-metre-tall guyed mast, carrying a double conical cage antenna with a diameter of 64 metres. This construction allowed its usage for all mediumwave frequencies, and therefore also as backup antenna for Deutschlandfunk's mediumwave transmitters at other sites. The directional antenna consisted of two horizontal dipole
Dipole
In physics, there are several kinds of dipoles:*An electric dipole is a separation of positive and negative charges. The simplest example of this is a pair of electric charges of equal magnitude but opposite sign, separated by some distance. A permanent electric dipole is called an electret.*A...
s which were mounted on 4.85-metre-tall guyed masts at a height of 75 metres, with a radiation maximum showing in northeast and southwest direction. As the omnidirectional antenna could not be used for the full available transmission power of 700 kW, in 1974 a 95-metre-tall guyed ground-fed mast radiator was built. A transmission power of 1050 kW was also possible by switching the third backup transmitter in parallel, but for economical reasons was never used. The transmitter was now run during the day with 700 kW and omnidirectional radiation, and at night with 350 kW and directional radiation, and was also used in the evenings for transmitting English-language programmes.
The introduction of the wave plan of Geneva
Wave plan of Geneva
The Geneva Frequency Plan of 1975 is the internationally agreed frequency plan which was drawn up to implement the provisions of the Final Acts of the Regional Administrative LF/MF Broadcasting Conference held in Geneva, Switzerland, in...
resulted in an increase of the transmission frequency from 1538 kHz to 1539 kHz. Mainflingen's daily operation mode was not affected. However, according to the wave plan, it was no longer allowed to use the double conical antenna as backup antenna for Deutschlandfunk's other mediumwave transmitters. The regulations of the wave plan of Geneva do not normally allow operation of backup transmitters more than 50 kilometres away from the standard site without special coordinative measures. This antenna was therefore dismantled in 1982.
After March 1, 1983 Deutschlandfunk was also broadcast at night using omnidirectional radiation, and the four masts of the directional antenna was dismantled afterwards. From April 1, 1988 the transmission power was reduced to 350 kW. Beside the bad groundwave propagation of the used frequency, broadcasts from the transmitter were only sufficiently well-received durin daytime, despite the high power output. This resulted in a shut-down of the transmitter on December 31, 1994, some years after the cancellation of foreign language transmissions.
As a replacement, Saarländischer Rundfunk
Saarländischer Rundfunk
Saarländischer Rundfunk is a public radio and television broadcaster for the German Bundesland of Saarland, with its headquarters in the Broadcasting House Halberg in Saarbrücken. SR is a member of the ARD.- Finances :...
's Heusweiler transmitter was leased. It was first planned to demolish the Mainflingen facility, but on April 1, 1996 Evangeliums-Rundfunk (ERF), a religious broadcaster, which already hired transmission time at Trans World Radio restarted its operation.
Several disputes between Deutsche Telekom
Deutsche Telekom
Deutsche Telekom AG is a telecommunications company headquartered in Bonn, Germany. It is the largest telecommunications company in Europe....
and the Mainhausen
Mainhausen
Mainhausen is a community of over 9,000 in the Offenbach district in the Regierungsbezirk of Darmstadt in Hesse, Germany.-Location:Mainhausen is one of 13 towns and communities in the Offenbach district, lying in the southernmost part of Hesse right on the boundary with Bavaria...
municipality occurred, as after the relaunch, problems with electromagnetic influence of electric devices were reported. Local residents were therefore opposed to continued use of the transmitter. In 1998 it was decided that the site could be used for mediumwave transmission and modernization of the facility started. First the old transmitter was replaced by a new, fully transistor
Transistor
A transistor is a semiconductor device used to amplify and switch electronic signals and power. It is composed of a semiconductor material with at least three terminals for connection to an external circuit. A voltage or current applied to one pair of the transistor's terminals changes the current...
ized transmitter, which would be also able to operate in DRM
Digital Radio Mondiale
Digital Radio Mondiale is a set of digital audio broadcasting technologies designed to work over the bands currently used for AM broadcasting, particularly shortwave...
mode.
In order to allow a good night-time transmission without causing too many problems with electromagnetic influence, a cross-dipole antenna with a radiation maximum pointing vertically into the sky was built in early 2006. This antenna, which is one of the few applications of circular polarisation for broadcasting, is mounted on 5 guyed masts. The central mast of this antenna is grounded. It carries the feeder cables running to the dipole, while the masts at the edge are standing on insulators and grounded via inductance
Inductance
In electromagnetism and electronics, inductance is the ability of an inductor to store energy in a magnetic field. Inductors generate an opposing voltage proportional to the rate of change in current in a circuit...
s in such way that they radiate as low a frequency as possible. In this way, undesired parasitic radiations, which are the cause of electromagnetic influence, are suppressed. It is also interesting to know that the radiated wave must be right-hand polarized, otherwise the signal reflected on the ionosphere
Ionosphere
The ionosphere is a part of the upper atmosphere, comprising portions of the mesosphere, thermosphere and exosphere, distinguished because it is ionized by solar radiation. It plays an important part in atmospheric electricity and forms the inner edge of the magnetosphere...
would be 20 dB
Decibel
The decibel is a logarithmic unit that indicates the ratio of a physical quantity relative to a specified or implied reference level. A ratio in decibels is ten times the logarithm to base 10 of the ratio of two power quantities...
less strong. In spring 2006 this new antenna went into service. It is used only for night-time transmissions, as the desired ionospheric reflection occurs only at night. During the day the old mast is used.
External links
- Mainflingen Medium Wave Transmitter on skyscraperpage.com
- Mainflingen 1539 kHz (in German)
- Mainflingen Kreuzdipol (published by www.waniewski.de in German)
- Mainflingen cross dipole (published by www.waniewski.de in English)
- Horizontal Task for TRANSRADIO
- Aerial Photo from WikiMapia
- Aerial photo of the mast from Google Maps
See also
- Mainflingen longwave transmitterMainflingen longwave transmitterMainflingen longwave transmitter is a large facility for commercial longwave transmissions at Mainflingen, Hesse, Germany, which was built in 1956. It uses several T- and triangle antennas, which are mounted on guyed masts of lattice steel, insulated against ground...