A short write up on radio.
Beginning in the early 1890s, Alexander Stepanovich Popov conducted experiments along the lines of Hertz's research. In 1894-95 he built his first radio receiver, an improved version of coherer-based design by Oliver Lodge. He presented it to the Russian Physical and Chemical Society on May 7, 1895 — the day has been celebrated in the Russian Federation as "Radio Day". The paper on his findings was published the same year (December 15, 1895). Popov had recorded, at the end of 1895, that he was hoping for distant signaling with radio waves.
In the years that followed, Popov worked on his design. His receiver proved to be able to sense lightning strikes at distances of up to 30 km, thus functioning as a lightning detector. In late 1895, Popov built a version of the receiver that was capable of automatically recording lightning strikes on paper rolls. Popov's system was eventually extended to function as a wireless telegraph, with a Morse key attached to the transmitter. There's some dispute regarding the first public test of this design. It is frequently stated that Popov used his radio to send a Morse code message over a distance of 250 m in 26 March 1896 (three months before Marconi's patent was filed). However, contemporary confirmations of this transmission are lacking. It is more likely that said experiment took place in December 1897.In 1900 a radio station was established under Popov's instructions on Hogland island (Suursaari) to provide two-way communication by wireless telegraphy between the Russian naval base and the crew of the battleship General-Admiral Apraksin. By February 5 messages were being received reliably. The wireless messages were relayed to Hogland Island by a station some 25 miles away at Kymi (nowadays Kotka) on the Finnish coast.
Marconi
Guglielmo Marconi is said to have read, while on vacation in 1894, about the experiments that Hertz did in the 1880s and about Tesla's work. It was at this time that Marconi began to understand that radio waves could be used for wireless communications.
Marconi's early apparatus was a development of Hertz’s laboratory apparatus into a system designed for communications purposes. At first Marconi used a transmitter to ring a bell in a receiver in his attic laboratory. He then moved his experiments out-of-doors on the family estate near Bologna, Italy, to communicate further. He replaced Hertz’s vertical dipole with a vertical wire topped by a metal sheet, with an opposing terminal connected to the ground. On the receiver side, Marconi replaced the spark gap with a metal powder coherer, a detector developed by Edouard Branly and other experimenters. Marconi transmitted radio signals for about a mile at the end of 1895.
By 1896, Marconi introduced to the public a device in London, asserting it was his invention. Despite Marconi's statements to the contrary, though, the apparatus resembles Tesla's descriptions in the widely translated articles. He filed a patent on his system with the British Patent Office on June 2, 1896.
Marconi's reputation is largely based on these accomplishments in radio communications and commercializing a practical system. His demonstrations of the use of radio for wireless communications, equipping ships with life saving wireless communications, establishing the first transatlantic radio service, and building the first stations for the British short wave service, have marked his place in history.
Transatlantic transmissions
In 1901, Marconi claimed to have received daytime transatlantic radio frequency signals at a wavelength of 366 metres (820 kHz).[22][23][24] There are various science historians, such as Belrose and Bradford, who have cast doubt that the Atlantic was bridged in 1901, but other science historians have taken the position that this was the first transatlantic radio transmission. The Poldhu to Newfoundland transmission claim has been criticized.Guglielmo Marconi (Italian pronunciation: [ɡuʎˈʎɛːlmo marˈkoːni]; 25 April 1874– 20 July 1937) was an Italian inventor, best known for his development of a radio telegraph system, which served as the foundation for the establishment of numerous affiliated companies worldwide. He shared the 1909 Nobel Prize in Physics with Karl Ferdinand Braun "in recognition of their contributions to the development of wireless telegraphy" and was ennobled in 1924 as Marchese Marconi.
