History of radio around the world

1864-1900: theory first, then the waves

2. 1864-1865
   James Clerk Maxwell describes in mathematics that electromagnetic waves exist and travel at roughly the speed of light. Sources give 1864 or 1865, depending on whether you count the first presentation or the publication. He did not build a device.
3. 1886-1888
   Heinrich Hertz makes Maxwell's waves visible in his laboratory with a spark transmitter and a ring-shaped receiver. He himself sees little practical value in it. The unit of frequency, the hertz, is named after him.
4. 1892
   The Frenchman Édouard Branly shows a detector of metal filings in a glass tube: the coherer. Oliver Lodge works on a similar idea around the same time and gives the device its name.
5. 1894-1895
   Lodge in England and the Russian Aleksandr Popov each build a transmitter and a receiver for wireless signals. Outside Russia Popov is little known, but according to some sources he and Lodge did this a year before Marconi.
6. Around 1900
   The Indian physicist Jagadish Chandra Bose is among the early experimenters with wireless telegraphy. In the book Signalling through space without wires (1900), Lodge describes the work of Hertz and his successors; the background photo below comes from that book.

Background photo: Diagram of a receiver from Signalling through space without wires (1900), Internet Archive Book Images, no restrictions (public domain). Resized and tinted.

1895-1943: Marconi, Tesla and the patent dispute

2. 1895-1897
   Guglielmo Marconi builds his first wireless connections. In 1897 he is granted patent 7777 in England and founds his own wireless telegraph company. He makes existing ideas practical and commercially usable; that is his great merit.
3. 1900
   Nikola Tesla is granted US patent 645,576, applied for in 1897, on the tuning of wireless circuits. His plan for a worldwide transmission system at Wardenclyffe on Long Island fails for lack of money.
4. 12 December 1901
   Marconi reports that the letter S (three dots) has been received across the Atlantic Ocean, from Poldhu in Cornwall to Signal Hill in Newfoundland. For the first time a wireless signal crosses an ocean.
5. 1909
   Marconi shares the Nobel Prize in Physics with Karl Ferdinand Braun for their contributions to wireless telegraphy.
6. 1943
   The US Supreme Court rules in a long-running patent dispute over the tuning of radio circuits and lets Tesla's patent stand, after his death. How broad that ruling was exactly is described differently by sources; some say that it brought down Marconi's patents, others limit it to this one element.

1904-1919: speech, music and the valve

2. 1904
   The Briton John Ambrose Fleming builds the first electron tube with two electrodes, the diode.
3. 1906
   Lee De Forest adds a grid and creates the audion, a triode that can amplify weak signals. Without amplification receivers were silent and transmitters with speech and music were hardly possible. Some sources give 1907 for the first triode.
4. 24 December 1906
   Reginald Fessenden transmits speech and a music recording from Massachusetts to ships at sea and repeats it on New Year's Eve. It is one of the earliest broadcasts with speech and music. What exactly could be heard is not known for certain.
5. 29 October 1913
   Edwin Armstrong applies for a patent on the regenerative receiver, which makes the signal much stronger through feedback. De Forest later also applies for a patent on feedback; the US Supreme Court ruled in his favour, something experts still dispute to this day.
6. 1919
   In The Hague, Hanso Idzerda begins his music broadcasts under the call sign PCGG. His story is on the page History of radio in the Netherlands.

Background photo: Lee De Forest with audion tubes, unknown maker, public domain. Resized and tinted.

1919-1926: the first broadcasters per country

Who counts as first? Wikipedia's list on the introduction of radio per country counts the first broadcast for the public, and makes no distinction between a trial and regular broadcasts. That is why the year and the station it names are listed below, per country in order of year. There is no simple winner: according to that list the Netherlands starts in 1919, while Argentina calls itself the first formal station in the world in 1920.

2. 1919
   Netherlands: PCGG in The Hague (Idzerda). The first Dutch broadcasting association, the HDO, follows in 1923 in Hilversum.
3. 27 August 1920
   Argentina: the opera Parsifal is broadcast from the Coliseo theatre in Buenos Aires. The Argentine page calls LOR Radio Argentina the first formal radio station in the world; that is a claim of its own and not an independent fact.
4. 1920
   United States: the list names 2XG in New York (1916) and, in 1920, the stations 8MK (WWJ) in Detroit and 8XK (KDKA) in Pittsburgh. KDKA is often named as the first commercial station, with its coverage of the presidential election on 2 November 1920. Canada: XWA in Montreal, later CFCF.
5. 1921
   France: Radio Tour Eiffel in Paris. Australia: 2CM in Sydney. Mexico: TND in Monterrey.
6. 1922
   United Kingdom: 2MT in Writtle (by Marconi) and 2LO in London; the BBC is founded in the same year. Brazil: SPE in Rio de Janeiro. New Zealand: a station in Dunedin, later 4AB.
7. 1923
   Germany: Funk-Stunde in Berlin. India: the Radio Club of Bombay (2FV). South Africa: JB in Johannesburg. Belgium: Radio Bruxelles. Switzerland: 2HB in Lausanne. China: a station in Shanghai (the list gives 1926 for the whole country).
8. 1924
   Soviet Union: Moscow, with stations of the Comintern and the trade union. Italy: IRO in Rome.
9. 1925
   Japan: JOAK in Tokyo. Sweden: Radiotjänst in Stockholm.

Background photo: Reception of a radiotelephone broadcast in Radio for everybody (Austin Lescarboura, 1922), Internet Archive Book Images, no restrictions (public domain). Resized and tinted.

1933-1958: FM, the transistor and radio in your pocket

2. 1933
   Armstrong is granted a patent on frequency modulation (FM): sound that is clear and free of interference, because the wave varies in frequency and not in strength. The patent alone did little for him: his fight with RCA over FM lasted years, and his second wife won that case in 1967, after his death.
3. 1947
   The first working transistor is made. A transistor can amplify like the valve, but is small, economical and less fragile.
4. Mid-1950s
   The first portable transistor radios come on the market. The set in the photo under the next heading, the Philco model T7-126 from 1956, was that brand's first transistor radio and could only receive the medium wave band.
5. 1957-1958
   Jack Kilby (Texas Instruments) and Robert Noyce (Fairchild) make the integrated circuit. This starts the miniaturisation of electronics that later ends up in your phone and in DAB radios, among other things.

Background photo: Edwin Armstrong with his superregenerative receiver, unknown maker, public domain. Resized and tinted.

So who did invent radio?

Nobody alone. Maxwell predicted the waves, Hertz made them, Branly and Lodge developed detection, Popov and Marconi built working connections, Fessenden brought speech and music into it, De Forest and Armstrong made amplification and better reception possible. Tesla did important work on tuning and applied for patents on it. Experts differ on who deserves the most credit: one article says Marconi's name is wrongly attached to the invention, another calls Tesla the real father of radio. A fair summary is that the answer depends on what you mean by inventing.

Background photo: Philco transistor radio, model T7-126 (1956), Joe Haupt, CC BY-SA 2.0. Resized and tinted.