Sunday, June 2, 2013

Sweden - Varberg Radio Station

World Heritage Grimeton Radio Station.

Sent by Jennie and staff at the Radio Station.

The Varberg radio station at Grimeton is an exceptionally well-preserved example of a type of telecommunication centre, representing the technological achievements by the early 1920s, as well as documenting further development over some three decades.
The site is located 7 km east of Varberg in the Parish of Grimeton, in south-western Sweden. The site comprises 109.9 ha of land with buildings housing the Alexanderson ultra-long wave radiotelegraph transmitter constructed in 1922-24. This includes the towers carrying the antenna installation, short-wave transmitters with their antenna, and a residential area with housing for the station staff.
The main property consists of the original station site, with the exception of an area containing the 'new' transmitter building and the antenna mast of Teracom AB's broadcasting station. The main buildings were designed by architect Carl Åkerblad in neoclassical style. Inside the transmitter building, about half the area of the transmitter hall is occupied by the Alexanderson 200 kW high-frequency alternator and its associated equipment: control racks, auxiliary machinery, high-frequency transformers and the Alexanderson magnetic modulator. All are in operative condition. The other half of the hall contains short-wave transmitters installed from the late 1930s onwards. These have remained in operational condition, although now out of service, except for two transmitters that are still occasionally used. Most of the site is occupied by the antenna plant. Its aerial system is supported by six steel towers, each 127 m high, arranged in a straight line 380 m from each other. The towers were designed by and constructed under the supervision of Professor Henrik Kreüger. Each tower is associated with a radiating antenna element stretching from the top to an inductance coil on the ground. Buried in the ground is a counterpoise network of copper wire, extending to the borders of the site and adjacent properties. A system of electricity wires on wooden poles connects the inductance coils with the buried network. An ice-melting transformer house close to the transmitter hall provides electricity to heat up and free the wires of ice in the winter.
In the 19th century, scientific and technical developments in telecommunication were based on inventions by people such as Faraday, Clerk Maxwell, Hertz and Marconi. The use of telegraph started in the second half of the century. From here, telegraphic and radio transmissions developed further in the early 20th century. The first experiments to have wireless transmission of speech across the Atlantic were in 1915 and 1919. In Sweden, the contribution of the chief engineer Ernst Fredrik Werner Alexanderson (1878-1975) was decisive for taking these techniques further into practice. He was responsible for a number of innovations, including the high-frequency alternator for continuous (undamped) electric oscillations, which led to the improvement of telegraphic wireless communication over large distances as well as providing the basis for wireless telephony, later leading into radio broadcast. He developed the 'multiple-tuned antenna', a system of cooperating vertical antennae, which resulted in an important improvement of long-wave radio communication. Alexanderson promoted the plan for a global radiotelegraphic network after the First World War, when the global network of radiotelegraphic stations was constructed, according to Alexanderson's system of which Varberg Radio Station at Grimeton became a part. The structural engineer Henrik Kreüger (1882-1953) was responsible for the six antenna towers at Grimeton, then the tallest built structures in Sweden.
When the rapid development in electronic transmitters for long-distance wireless communication made the Alexanderson technique obsolete, the other radio stations were either modified or demolished. Varberg Radio Station, in regular service use until the 1960s, survives today, but it has remained an industrial site until 1997, since it has been partly opened to the public. Some equipment is still used by the Swedish Navy or for other purposes. (Source)

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