Mediumwave Transmitter Mainflingen

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 transmitters. 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 dipoles 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.

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