History of the site
The site is famous as the location of Poldhu Wireless Station, Guglielmo Marconi’s transmitter for the first transatlantic radio signal.
The station’s fifty acre (200,000 m²) plot was bought in 1900 and construction work ran from October 1900 to January 1901, to a design by RN Vyvyan, while Professor John Ambrose Fleming designed the transmitter. The original 20 mast circular cone-shaped aerial was destroyed in a storm on September 17, 1901. For Marconi’s experiments a temporary installation of two 200 foot (61 m) masts with a fan shaped aerial was used. The transmitter operated with a power of roughly 13 kW and a wavelength usually estimated at 366 metres. Marconi and two assistants travelled to Newfoundland in December 1901 and on December 12th the pre-arranged signal of three dots (the letter ‘S’ in Morse code) was heard by Marconi on Signal Hill at St. John’s.
The original mast layout was not rebuilt, but was replaced with a four lattice wooden mast design, 215 feet (66 m) high and forming a 200 foot (61 m) square, by early 1902.
Experiments were carried out for several years to establish a regular telegram service with Glace Bay in Canada, but in 1906 a powerful low frequency station was built near Clifden in the west of Ireland to communicate with a similar one at Glace Bay. Poldhu continued to communicate with deep sea shipping using the call sign MPD and also transmitted a regular nightly Morse code news bulletin using the call sign ZZ. This was used by liners to print daily newspapers, whose owners paid for the copyright.
The station was taken over by the Royal Navy during the First World War.
After the war Marconi used the site for his shortwave experiments, with transmissions by Charles Samuel Franklin to Marconi on the yacht Elettra in the Cape Verde Islands in 1923 and near Beirut in 1924. The ground-breaking results of these experiments took the world by surprise and quickly resulted in his development of the Beam Wireless Service for the British General Post Office. The service opened from the Bodmin Beam Station beaming to Canada on 25 October, 1926. The Tetney Beam Station to Australia opened on 8 April 1927, the Bodmin Beam Station to South Africa on 5 July 1927, the Dorchester Beam Station to India on 6 September 1927 and shortly afterwards to Argentina, Brazil and the United States.
Poldhu continued to operate as a research station until 1933. The site was cleared in 1935 and six acres (24,000 m²) of cliff -top were gifted to the National Trust in 1937, with the rest of the site added in 1960. The site has a granite monument, and a number of concrete foundations and earth structures also remain. On the centenary of the first transatlantic transmission the Marconi Centre was opened close to the site by the efforts of the Poldhu Amateur Radio Club, the National Trust and Marconi plc.
The more substantial building near the site, originally the Poldhu Hotel, built in 1898, is currently a care home.