Editing Guglielmo Marconi (section)

====Transatlantic transmissions====
[[File:Marconi at newfoundland.jpg|thumb|upright=1.5|Marconi watching associates raising the kite (a "Levitor" by [[Baden Baden-Powell]]<ref>{{cite web|url=http://www.carnetdevol.org/Wireless/marconi-transatlantique.html|title=First Atlantic Ocean crossing by a wireless signal|archive-url=https://web.archive.org/web/20130130034523/http://www.carnetdevol.org/Wireless/marconi-transatlantique.html|archive-date=30 January 2013|website=Carnetdevol.org.|accessdate=12 July 2012}}</ref>) used to lift the antenna at [[St. John's, Newfoundland and Labrador|St. John's, Newfoundland]], December 1901]]

[[File:Detector magnetico Marconi 1902 - Museo scienza e tecnologia Milano.jpg|thumb|left|Magnetic detector by Marconi used during the experimental campaign aboard a ship in summer 1902, exhibited at the [[Museo Nazionale Scienza e Tecnologia Leonardo da Vinci]] of Milan]]

At the turn of the 20th century, Marconi began investigating a means to signal across the Atlantic to compete with the [[transatlantic telegraph cable]]s. Marconi established a wireless transmitting station at Marconi House, [[Rosslare Strand]], [[County Wexford]], in 1901 to act as a link between [[Poldhu]] in [[Cornwall]], England, and [[Clifden]] in [[Connemara]], [[County Galway]], Ireland. He soon made the announcement that the message was received at [[Signal Hill (Newfoundland and Labrador)|Signal Hill]] in [[St. John's, Newfoundland and Labrador|St. John's]], [[Newfoundland and Labrador|Newfoundland]] (now part of [[Canada]]), on 12 December 1901, using a {{convert|500|ft|m|adj=on}} kite-supported antenna for reception – signals transmitted by the company's new high-power station at [[Poldhu]], Cornwall. The distance between the two points was about {{convert|2200|mi|km}}. It was heralded as a great scientific advance, yet there also was – and continues to be – considerable scepticism about this claim. The exact wavelength used is not known, but it is fairly reliably determined to have been in the neighbourhood of 350 metres (frequency ≈ 850&nbsp;kHz). The tests took place at a time of day during which the entire transatlantic path was in daylight. It is now known (although Marconi did not know then) that this was the worst possible choice. At this medium wavelength, long-distance transmission in the daytime is not possible because of the heavy absorption of the skywave in the ionosphere. It was not a blind test; Marconi knew in advance to listen for a repetitive signal of three clicks, signifying the Morse code letter ''S''. The clicks were reported to have been heard faintly and sporadically. There was no independent confirmation of the reported reception, and the transmissions were difficult to distinguish from atmospheric noise. A detailed technical review of Marconi's early transatlantic work appears in John S. Belrose's work of 1995. The Poldhu transmitter was a two-stage circuit.<ref>{{cite journal|doi=10.1109/MAP.2004.1305565|year=2004|journal=IEEE Antennas and Propagation Magazine|volume=46|issue=2|page=130|title=Marconi and the History of Radio}}</ref><ref>{{cite book|doi=10.1049/cp:19950787|chapter=Fessenden and Marconi: Their differing technologies and transatlantic experiments during the first decade of this century|title=International Conference on 100 Years of Radio|date=1995|last1=Belrose|first1=J.S.|volume=1995|pages=32–43|isbn=0-85296-649-0 }}</ref>

[[File:Guglielmo Marconi 1901 wireless signal.jpg|thumb|Marconi demonstrating apparatus he used in his first long-distance radio transmissions in the 1890s. The transmitter is at the right, the receiver with paper tape recorder at the left.]]
[[File:Guglielmo, Marchese Marconi. Colour lithograph by Sir L. War Wellcome V0003849.jpg|upright|thumb|Marconi caricatured by [[Leslie Ward]] for ''[[Vanity Fair (British magazine)|Vanity Fair]]'' magazine, 1905]]

Feeling challenged by sceptics, Marconi prepared a better-organised and documented test. In February 1902, the SS ''Philadelphia'' sailed west from Great Britain with Marconi aboard, carefully recording signals sent daily from the Poldhu station. The test results produced [[Magnetic detector|coherer-tape]] reception up to {{convert|1550|mi|km}}, and audio reception up to {{convert|2100|mi|km}}. The maximum distances were achieved at night, and these tests were the first to show that radio signals for [[medium wave]] and [[longwave]] transmissions travel much farther at night than during the day. During the daytime, signals had been received up to only about {{convert|700|mi|km}}, less than half of the distance claimed earlier at Newfoundland, where the transmissions had also taken place during the day. Because of this, Marconi had not fully confirmed the Newfoundland claims, although he did prove that radio signals could be sent for hundreds of kilometres (miles), despite some scientists' belief that they were limited essentially to line-of-sight distances.

On 17 December 1902, a transmission from the Marconi station in [[Glace Bay]], Nova Scotia, Canada, became the world's first radio message to cross the Atlantic from North America. In 1901, Marconi built a station near [[Wellfleet, Massachusetts|South Wellfleet, Massachusetts]], that sent a message of greetings on 18 January 1903 from United States President [[Theodore Roosevelt]] to King [[Edward VII]] of the United Kingdom. However, consistent transatlantic signalling was difficult to establish.<ref>{{Cite web|title=TR Center – Talking Across the Ocean|url=https://www.theodorerooseveltcenter.org/Blog/Item/Talking%20Across%20the%20Ocean|access-date=2021-03-12|website=theodorerooseveltcenter.org}}</ref>

Marconi began to build high-powered stations on both sides of the Atlantic to communicate with ships at sea, in competition with other inventors. In 1904, he established a commercial service to transmit nightly news summaries to subscribing ships, which could incorporate them into their on-board newspapers. A regular transatlantic radio-telegraph service was finally begun on 17 October 1907<ref>{{cite journal|title=The Clifden Station of the Marconi Wireless Telegraph System|journal=Scientific American|date=23 November 1907}}</ref><ref>{{cite news|url=http://marconi100.ca/clip/marconi-sydpost19071024.html|title=Second Test of the Marconi Over-Ocean Wireless System Proved Entirely Successful|archive-url=https://web.archive.org/web/20131019025942/http://marconi100.ca/clip/marconi-sydpost19071024.html|archive-date=19 October 2013|newspaper=Sydney Daily Post|date=24 October 1907}}</ref> between [[Clifden]], Ireland, and [[Glace Bay]], but even after this the company struggled for many years to provide reliable communication to others.