File:Marconi Poldhu UK radio transmitter - made first transatlantic transmission 1901.jpg
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Summary
[edit]DescriptionMarconi Poldhu UK radio transmitter - made first transatlantic transmission 1901.jpg |
English: Experimental spark radio transmitter at Poldhu, UK used by Guglielmo Marconi to make the first transatlantic radio transmission 12 December 1901. Designed by Prof. John Ambrose Fleming of University College, London, and built in secret in 1900-1901 it was an inductively-coupled transmitter with two cascaded spark gaps firing at different rates, and three resonant circuits, powered by a 25 kW alternator turned by a combustion engine. It fed a vertical monopole antenna consisting of 50 wires in a fan shape suspended from a cable between two 160 foot poles. Marconi estimated the radiated power was around 10-12 kilowatts. The operating frequency is not known, since Marconi never measured frequency or wavelength but it is estimated to be around 500 kilohertz.
On 12 December 1901 Marconi reported he had received the radiotelegraphic signals on Signal Hill, St. John's on the coast of Newfoundland, 2,100 miles (3,400 kilometres) from the transmitter, using an unamplified, untuned coherer receiver attached to a 400 foot wire antenna held aloft with a kite. |
Date | |
Source | Retrieved from John Ambrose Fleming (1921) Fifty Years of Electricity: The memories of an electrical engineer, London, The Wireless Press, Ltd., Plate 4, facing p.313 |
Author | John Ambrose Fleming (died 18 April 1945) |
Licensing
[edit]Public domainPublic domainfalsefalse |
The author died in 1945, so this work is in the public domain in its country of origin and other countries and areas where the copyright term is the author's life plus 75 years or fewer. This work is in the public domain in the United States because it was published (or registered with the U.S. Copyright Office) before January 1, 1929. | |
This file has been identified as being free of known restrictions under copyright law, including all related and neighboring rights. |
https://creativecommons.org/publicdomain/mark/1.0/PDMCreative Commons Public Domain Mark 1.0falsefalse
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current | 21:41, 5 September 2024 | 1,265 × 920 (249 KB) | Chetvorno (talk | contribs) | Uploaded a work by John Ambrose Fleming (died 18 April 1945) from Retrieved from [https://archive.org/details/in.ernet.dli.2015.85348/page/n421/mode/2up John Ambrose Fleming (1921) Fifty Years of Electricity: The memories of an electrical engineer, London, The Wireless Press, Ltd., Plate 4, facing p.313] with UploadWizard |
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Author | Chris Burks |
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Date and time of data generation | 17:59, 29 February 2020 |
Horizontal resolution | 96 dpi |
Vertical resolution | 96 dpi |
Software used | GIMP 2.10.12 |
File change date and time | 14:20, 5 September 2024 |
Date and time of digitizing | 17:59, 29 February 2020 |
DateTimeOriginal subseconds | 73 |
DateTimeDigitized subseconds | 73 |
Unique ID of original document | xmp.did:24271fd6-8cb9-41cc-9993-7223f9d810f5 |