Transmitter Ismaning
The Transmitter Ismaning was a large radio station inaugurated in 1932. From 1932 to 1934 this transmitter, which replaced the transmitter in Munich-Stadelheim, used a T-antenna
A T-antenna is an antenna whereby "a vertical or sloping wire is connected to the approximate centre of a straight horizontal top wire" . This forms its characteristic "T"-shape.-External links:*...

 as transmitting antenna, which was hung up two 115-meter-high freestanding wood framework towers. Since this had an unfavorable vertical radiation pattern, one of the two towers was demolished in 1934 and rebuilt on a 39 meters high wood base. During these works transmitting took place with the help of a l-Antenne, which was stretched between the other tower and a small wood mast. After completion of the new wood tower, which was 156 meters tall (with the arms carrying its antenna it was 163 meters tall) the second wood tower was dismantled and rebuilt in 1935 in Nuremberg-Kleinreuth
Transmitter Nuremberg-Kleinreuth
The Transmitter Nuremberg-Kleinreuth was a broadcasting facility for medium-wave. It was founded in 1927 in Nuremberg-Kleinreuth at the former Broadcast Street 24, now Sigmund Street 181, in order to supply the northern areas of Bavaria with broadcast programs in the medium-wave band.Between 1927...

, where it served up to the year 1961 as a transmitting tower for medium wave. The wood tower in Ismaning carried a dipole antenna, whose point of feeding was in 120 meters height. From this point of feeding several wires run to the arms on the tower top and to fastening spots in a height of 80 meters. At this height a differential transformer was installed in a small housing inside the tower; its task was to prevent the drain of the radiated high frequency over the feeder. This antenna, developed by the company Lorenz, was called "H√∂hendipol". It was one for the transmitter frequency of 740 kHz, which was used from 1934 to 1950, optimized fading-reducing transmitting antenna. However according to the wave plan of Copenhagen, which required directional radiation at night times, it could be only used during daylight hours after 1950.
In 1969 this antenna was dismantled after a new medium wave transmitting mast was built. Between 1969 and 1977 the wood tower was used for carrying transmitting antennas for FM. In 1977 a 100-meter-high guyed steel framework mast also took over this function, so the wood tower had no more function after 1977.
The state of the tower worsened more and more after 1977 and it seemed to be impossible to repair this tower, which was nicknamed "Bavarian Eiffel Tower" and which was already under protection as a monument.
On March 16, 1983 it was blown up.
Still today there are its concrete foundations and the tuning house, which once stood under the tower.

The transmission facility Ismaning
Ismaning is a municipality in Bavaria, Germany, located near Munich. In 2006 it had 14,638 inhabitants. Near Ismaning there is a large broadcasting facility called Transmitter Ismaning....

 is used for transmitting the first program of the Bavarian Broadcasting company
Bayerischer Rundfunk
Bayerischer Rundfunk [Bavarian Broadcasting] is the public broadcasting authority for the German Freistaat of Bavaria, with its main offices located in Munich. BR is a member of ARD.- Legal foundation :...

 on the medium wave frequency
Frequency is the number of occurrences of a repeating event per unit time. It is also referred to as temporal frequency.The period is the duration of one cycle in a repeating event, so the period is the reciprocal of the frequency...

 801 kHz (transmission power 600 kilowatts until 1994, now 100 kilowatts) and for allprogrammes of the Bavarian Broadcasting company in the FM range. Until 1994 there was also a transmitter of AFN
American Forces Network
The American Forces Network is the brand name used by the United States Armed Forces American Forces Radio and Television Service for its entertainment and command internal information networks worldwide...

 at Ismaning.

For the AM transmissions a 171.5 metre high guyed steel tube mast is used. This mast is insulated against ground and is designed as fading reducing transmission aerial with multiple feeding. Therefore it is separated in 56 metre and 117 metre height by an insulator.

Restrictions of the waveplan of Geneva required a minimum of radiation in direction Northeast, in order to reduce interferences of the transmitter Saint Petersburg
Saint Petersburg
Saint Petersburg is a city and a federal subject of Russia located on the Neva River at the head of the Gulf of Finland on the Baltic Sea...

, Russia
Russia or , officially known as both Russia and the Russian Federation , is a country in northern Eurasia. It is a federal semi-presidential republic, comprising 83 federal subjects...

, on the same frequency, if transmission power is 600 kilowatts at night. Therefore in 1978 a 71 metre high guyed steel-framework mast, which is insulated against ground, was built in 1978 near the mast upper mentioned. Because a power reduction toward Northeast is not necessary with a transmission power of 100 kilowatts, this mast is now obsolete, but it is still there.

As back-up aerial a 105 metre high, guyed steel framework mast was built in 1947 close to the transmitter building. This mast, which was originally used for transmitting the program of AFN was until 1969 126 metre high and carried from 1958 to 1969 aerials for FM transmissions.

Restriction by the waveplan of Kopenhagen had the result, that the mediumwave transmitter of the Bavarian broadcasting company had to work with directional radiation with minimum toward Northeast after 1951 at nighttime. This type of radiation was not possible with the aerial on the wood framework tower and a directional aerial consisting of two insulated guyed radio masts with a height of 94 metres had to be built.

This aerial was until 1969 for transmitting the program of the Bavarian broadcasting company during nighttime in service. After 1969 it was used until its shutdown in 1994 for transmitting the program of AFN on 1107 kHz. In difference to the time before 1969 omnidirectional radiation was used. One mast was used and the other one was a spare unit.

As aerials for shortwave transmissions of the Bavarian broadcasting company there are a dipol aerial, built in 1976, which hangs on two guyed steelframework masts with a height of 35 metres and a winkle dipole which hangs on three guyed steelframework masts with a height of 55 metres. The winkle dipol aerial went in service in 1980.

For FM-broadcasting transmission there is a silvery grey guyed steel framework mast with dipol arrays on its top near the station building. This mast, which was built in 1977, has a height of 100 metres and is the only mast at the transmitter Ismaning, which is grounded.

The Voice of America
Voice of America
Voice of America is the official external broadcast institution of the United States federal government. It is one of five civilian U.S. international broadcasters working under the umbrella of the Broadcasting Board of Governors . VOA provides a wide range of programming for broadcast on radio...

 ran until 1994 near the station of the Bavarian Broadcasting company a large shortwave transmission facility, which is nowadays completely demounted. The medium wave transmission facility of the Voice of America and Radio Free Europe/Radio Liberty
Radio Free Europe
Radio Free Europe/Radio Liberty is a broadcaster funded by the U.S. Congress that provides news, information, and analysis to countries in Eastern Europe, Central Asia, and the Middle East "where the free flow of information is either banned by government authorities or not fully developed"...

 operated by the International Broadcasting Bureau
International Broadcasting Bureau
The International Broadcasting Bureau is an entity within the Broadcasting Board of Governors , which is a U.S. independent agency. The IBB supports the day-to-day operations of Voice of America and the Office of Cuba Broadcasting...

 was shut down in March 2005. It consists of four guyed steel framework masts, which are insulated against ground. These masts were built in 1949 and renovated in the nineties and allow the realisation of a directional aerial with changeable directional characteristic.

In 2010 a 210 metres tall new guyed mast for FM-broadcasting was built.

Main medium wave transmission mast

Mast of directional antenna of Bavarian Broadcasting Company


Radio masts of VoA Ismaning


See also

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