From equations to sparks
In 1865 Maxwell publishes his theory: light is an electromagnetic wave, and such waves travel at the speed of light. From 1886 to 1888, in Karlsruhe, Hertz produces and detects them: a Ruhmkorff coil feeds a spark gap with two brass balls; the receiver is an open loop of wire, where a tiny spark jumps. Frequency: around 50 MHz. His 1887–1888 publications show reflection, refraction and polarisation. The line « my waves are of no use », put in his mouth, has no known primary source.
The radioconductor and the coherer
In 1890 Édouard Branly describes his radioconductor: a glass tube with filings between two electrodes; a nearby spark makes it conduct, a small knock gives it back its resistance. He uses the prefix « radio- », perhaps for the first time. His laboratory is kept at the Musée Édouard Branly (Institut catholique de Paris), not to be confused with the Musée du quai Branly. On 1 June 1894 Oliver Lodge names the device « coherer »; he is credited with a tapper that knocks the tube (a detail to be checked). On 7 May 1895 Popov presents a coherer storm receiver: the IEEE gave it a Milestone in 2005.
Marconi
- 2 June 1896: aged 22, Marconi files in London what is presented as the first wireless telegraphy patent (no. 12039, granted on 2 July 1897). He founds his company in July 1897.
- 27 March 1899: first link across the Channel, Wimereux – South Foreland, about 50 km, before a French commission; a message pays tribute to Branly (its exact day is disputed).
- 12 December 1901: at Signal Hill, Marconi and Kemp say they hear the « S » sent from Poldhu. Nothing was recorded, Kemp is the only witness apart from Marconi: the reception is still disputed. In February 1902, on board the Philadelphia, signals from Poldhu are recorded before witnesses.
- 1909: Nobel Prize in Physics for Marconi and Braun.
Paris and the Eiffel Tower
On 5 November 1898, Ducretet and Roger link the 3rd floor of the Eiffel Tower and the Panthéon in Morse, about 4 km apart; a plaque on the tower recalls it. In 1903, Ferrié's military antennas save the tower, threatened with demolition. On 23 May 1910 the first official time signals go out, with the Paris Observatory and the Bureau des longitudes: ships set their chronometers and work out their longitude. Ferrié then helps create the Bureau international de l'heure.
CQD, SOS
On 1 February 1904 the Marconi company imposes « CQD ». In 1906 the Berlin convention chooses « SOS » (···−−−···), simple and impossible to mistake, in force from 1 July 1908. Its first well-documented use is the Arapahoe's, on 11 August 1909. In the night of 14 to 15 April 1912, the Titanic's operators, Phillips and Bride, send CQD then mix CQD and SOS; the Carpathia arrives around 4 a.m., about four hours after the collision.
The radio amateurs
The American Radio Act of 13 August 1912 makes a licence compulsory and confines amateurs to 200 m and below. In 1914 Hiram Percy Maxim founds the ARRL. In the night of 27 November 1923 (the date most often given; the 28th, or even the 17th, according to other sources), Léon Deloy, 8AB, in Nice, makes with Fred Schnell (1MO) then John Reinartz (1XAM) the first two-way amateur contact across the Atlantic, in Morse, around 110 m (about 2.7 MHz). In April 1925 the Paris congress founds the IARU: 23 nations, Maxim as president (statutes adopted on the 17th, approved in plenary session on the 18th); 18 April is World Amateur Radio Day. On the French side, the REF is said to have been born in 1925 too; its exact dates are still to be checked.
The myths
The Supreme Court ruling of 21 June 1943 judges the validity of Marconi patents in a compensation case and relies mostly on John Stone Stone: it doesn't declare Tesla « inventor of radio ». The Titanic didn't send the first SOS. Popov's « Heinrich Hertz » message (1896) is still disputed: it was only told publicly in 1925. And « who invented radio? » has no simple answer: several pioneers contributed, some at the same time.
In the game The 1899 Morse message to decode (« VVV BRANLY ») and the message received on the coherer are exercise messages, made up for the game; so are the Morse speed and the tapping windows. The dates come from the sources.