Station radio Varberg

Brève description

Station radio Varberg

Justification d'inscription

Critère (ii) : La station radio Varberg de Grimeton est un monument exceptionnel qui témoigne du processus de développement de la technologie des communications dans la période qui suit la Première Guerre mondiale.

Critère (iv) : La station radio Varberg est un exemple exceptionnellement bien préservé d’un type de centre de télécommunications qui représente les réalisations technologiques du début des années 1920, et qui apporte des éléments d’information sur l’évolution des télécommunications sur quelque trois décennies.

Description longue

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.

Description historique

Au XIXe siècle, les progrès scientifiques et techniques des télécommunications découlèrent des inventions scientifiques comme celles de Michael Faraday, J.C. Maxwell, H. Hertz et Guglielmo Marconi. L'utilisation du télégraphe a débuté dans la seconde moitié du siècle. À partir de là, les transmissions radioélectriques et télégraphiques se sont développées au début du XXe siècle. Les premières expériences de transmission radio transatlantique datent de 1915 et 1919.

En Suède, l'ingénieur en chef Ernst Fredrik Werner Alexanderson (1878-1975) a contribué de manière décisive à l'application de ces techniques. Il a mis au point plusieurs innovations, notamment l'alternateur haute fréquence pour obtenir des oscillations sinusoïdales (une fréquence propre non amortie), qui a permis d'améliorer la communication sans fil longue distance et qui a fourni les bases techniques de la téléphonie sans fil et conduit ensuite à la radiodiffusion. Il a aussi développé l'antenne à accords multiples, un système d'antennes verticales qui permit une importante amélioration des communications radio en ondes longues.

Alexanderson promut le programme de réseau radiotélégraphique international mis en place après la Première Guerre mondiale. La Radio Corporation of America fut constituée pour l'exploitation et la commercialisation de ces réalisations techniques. De la fin de la Première Guerre mondiale jusqu'au milieu des années 1920, le réseau international de stations a été construit selon les plans d'Alexanderson, y compris la station radio Varberg de Grimeton, construite en 1922- 1924. L'ingénieur en génie civil Henrik Kreüger (1882- 1953) fut chargé de la construction des six pylônes à Grimeton, les plus hautes structures construites en Suède à l'époque.

À la fin des années 1920, avec le développement rapide des émetteurs électroniques pour les communications radio longue distance, la technique mise au point par Alexanderson devint obsolète. De toutes les grandes stations du réseau Alexanderson, il ne reste aujourd'hui que la station radio Varberg, les autres ayant été modifiées ou démolies. La station Varberg a été utilisée en service normal jusque dans les années 1960 puis elle a été maintenue en état de marche pendant encore plusieurs années.