# History of radio The **history of radio** runs from a laboratory confirmation of a mathematical prediction to a technology that now reaches almost every person on Earth in one form or another, and it did so by accretion: each decade added a use for [[Radio_wave|radio waves]] that the previous one had not imagined, from silent Morse code between ships to broadcasting, television, mobile telephony and beyond. A microsim carried over from the neighbouring [[Radar]] article, described below under Microsims, illustrates one of the later branches this history produced, pulsed echo-ranging, without this article needing its own dedicated sketch to make the underlying physics visible. No one person invented radio in the way a single patent might suggest. James Clerk [[James_Clerk_Maxwell|Maxwell]]'s theory predicted that oscillating electric and magnetic fields should propagate through space as a wave; Heinrich Hertz built the apparatus that showed the prediction was physically real; and a following generation of experimenters, engineers and entrepreneurs, working in India, Russia, Britain, Italy, Germany and the United States among other places, turned that laboratory result into telegraphy, then broadcasting, then the whole family of later services this article surveys. ## Discovery Maxwell's equations, published in the 1860s, implied that a changing electric field and a changing magnetic field should sustain each other and travel outward at the speed of light, a result with no experimental confirmation until Heinrich Hertz built a spark-gap transmitter and a separate resonant loop detector at Karlsruhe and, in a series of experiments in 1887 and 1888, showed that the sparks produced a detectable effect in the loop across an open laboratory room, and that the resulting waves could be reflected, refracted and polarized just as light can.[^hertz1888] Hertz considered the effect a confirmation of theory with no practical application; it was left to others to see a signalling system in it. ## Exploration of optical qualities Jagadish Chandra Bose, in Calcutta, pushed Hertz's demonstration toward wavelengths short enough, a few millimetres, to behave even more obviously like light: in an 1895 public demonstration at Presidency College he used a dielectric lens, a polarizer and a horn antenna to send waves at roughly 60 GHz through two intervening walls and across a lecture hall, ringing a bell and setting off a small charge of gunpowder by remote control to prove the waves had done measurable work at a distance.[^bose1895] The demonstration mattered less for any telegraph it led to directly than for confirming, independently of Hertz, that radio waves were a genuinely optical phenomenon: a beam that could be focused, polarized and blocked by an obstacle in ways early telegraphists needed to understand before they could design a reliable aerial or a directional system. ## Proposed applications Once Hertz's waves were public knowledge, proposals for using them multiplied faster than working apparatus did: signalling between ships without a visible flag or light, replacing wired telegraph lines across terrain too difficult to string a cable through, and warning of obstacles or other vessels in fog, an application later realised as radar rather than as anything built in the 1890s. Almost every serious proposal in this first decade assumed on-off signalling, coded messages sent the way a visible lamp or flag already was, because nobody yet had a transmitter capable of carrying a continuously varying waveform such as speech. ## Marconi and radio telegraphy Guglielmo [[Guglielmo_Marconi|Marconi]] was not the first to generate or detect radio waves, but he was the first to treat the distance a signal could travel as an engineering variable to be pushed rather than a fixed property of the physics, steadily lengthening his aerial, improving his earth connection, and testing over ever greater ranges from his family's estate near Bologna from 1895 onward. Refused support in Italy, he took the work to England in 1896, demonstrated it to the Post Office's William Preece, and received what is generally regarded as the first patent for a complete system of wireless telegraphy that same year; by 1897 he had founded a company to sell the system commercially rather than merely to demonstrate it.[^marconibio] ### Nautical and transatlantic transmissions Ships at sea were wireless telegraphy's first paying customers, since a wired telegraph line simply cannot follow a moving vessel, and Marconi's company equipped liners and warships through the first years of the twentieth century on that basis alone. Marconi's own most publicised claim came on December 12, 1901, when he reported receiving the Morse letter "S" at Signal Hill, Newfoundland, sent from Poldhu, Cornwall, some 3,500 kilometres away, a distance well beyond what a straight, [[Line-of-sight_propagation|line-of-sight]] path over the curve of the Earth allows, and one that depended, as later research clarified, on the signal reflecting back down from the [[Ionosphere|ionosphere]] rather than travelling in a straight line at all.[^transatlantic1901] ## Audio transmission Every transmitter described so far could only be switched on and off; carrying a continuously varying waveform such as speech or music needed a transmitter that held a steady carrier frequency and varied its amplitude smoothly, a genuinely different problem from making a spark loud enough to hear at a distance. Reginald Fessenden's alternator-based transmitter, built with General Electric's help, solved it mechanically by spinning a generator fast enough to produce a continuous radio-frequency wave directly, and Fessenden used one to demonstrate voice and music to invited engineers at Brant Rock, Massachusetts, on December 21, 1906; the more famous story of a Christmas Eve broadcast heard by ships at sea rests on no source earlier than the late 1920s and has been challenged by later historians.[^fessenden1906] ### Broadcasting Broadcasting, one signal meant for an unlimited and unaddressed audience, is a different business model from point-to-point telegraphy, and it took over a decade after Fessenden's demonstration for anyone to build that business rather than merely show the technology worked. KDKA in Pittsburgh, grown out of engineer Frank Conrad's amateur transmissions, received the first American license issued for the purpose on October 27, 1920, and made its first organized broadcast on November 2, reporting the Harding–Cox election returns to whichever nearby listeners owned a receiver.[^kdka1920] #### Wavelength and frequency Every broadcaster needed its own slice of spectrum, described in that era chiefly by wavelength rather than by the frequency figures now more common, and the sheer number of new stations chasing licenses through the early 1920s quickly showed that "find an open wavelength" was not a policy so much as an invitation to interference, a problem this article's later section on American radio regulation describes the government's response to. ## Radio companies Wireless telegraphy's commercial value made national governments treat it as a strategic asset almost immediately, and companies formed along national lines to match. ### British Marconi Marconi's own company, renamed Marconi's Wireless Telegraph Company in 1900, held a de facto monopoly over British and much international ship-to-shore [[Radio|wireless]] for two decades, a dominance built as much on an aggressive policy of refusing to let non-Marconi equipment communicate with Marconi shore stations as on any technical lead. ### Telefunken Germany's two largest electrical manufacturers, Siemens & Halske and AEG, had spent years disputing whose wireless patents controlled the field until Kaiser Wilhelm II ordered them in 1903 to merge their wireless interests into a single company, Telefunken, both to end the domestic argument between army and navy factions backing different manufacturers and to give Germany a national champion able to compete with Marconi's company abroad.[^telefunken1903] ## Technological development ### Bandwidth Every advance described in this section either demanded more bandwidth than the previous generation of equipment could supply or found a way to do more with the bandwidth already available; the tension between wanting more channels and having a fixed amount of usable [[Radio_spectrum|spectrum]] runs underneath the whole technical history of radio, not only its regulatory history. ### Amplitude-modulated (AM) [[Amplitude_modulation|Amplitude modulation]] was radio's first, and for three decades its only, practical way of carrying a continuously varying signal, and it remained broadcasting's dominant method into the FM era described later in this article; its own technical detail is treated in the paired article on [[AM_broadcasting|AM broadcasting]] rather than repeated here. ### Crystal set receivers The cheapest possible receiver needed no external power at all: a tuned circuit and a crystal [[Diode|diode]] detector, driving an earphone directly from the tiny power the received wave itself supplied, put a working [[Radio_receiver|receiver]] within reach of any household that could afford a length of aerial wire, well before broadcasting itself existed as an organized service. ### Vacuum tubes John Ambrose Fleming's two-electrode valve, patented on November 16, 1904, could rectify a radio-frequency signal but not amplify it; Lee De Forest's three-electrode Audion of 1906 added a control grid that could, giving the new tube the ability to boost a weak signal rather than merely detect it.[^fleming1904] Edwin Armstrong's regenerative circuit of 1912 fed part of a tube's own amplified output back into its input, turning modest gain into a far more sensitive receiver and, run past the point of stability, a practical self-sustaining transmitter oscillator in one and the same circuit.[^armstrong1912regen] #### Patents and licensing Fleming's, De Forest's and Armstrong's overlapping claims over the vacuum tube's basic operation produced years of patent litigation among the companies that had acquired rights to each of them, a dispute the United States government resolved during the First World War by pooling the major radio patents for wartime production and, after the war, by encouraging the cross-licensing arrangement that let the Radio Corporation of America build receivers using all three men's inventions at once. ### Loudspeakers An early receiver drove an earphone because that was all the power a vacuum-tube audio amplifier of the 1910s could deliver; the moving-coil [[Loudspeaker|loudspeaker]], developed through the 1920s alongside more powerful audio amplifier stages, let a single receiver fill a room instead of one listener's ear, a prerequisite for radio as a shared, living-room family activity rather than a solitary one. ### Transistor technology The vacuum tube's replacement, the point-contact [[Transistor|transistor]], was first demonstrated at Bell Telephone Laboratories on December 16, 1947, by John Bardeen and Walter Brattain, with William Shockley's group having organized the research that produced it; unlike a tube, it needed no heated filament and no evacuated glass envelope, and by the late 1950s had made a shirt-pocket portable receiver an ordinary consumer product rather than a novelty.[^transistor1947] ### Integrated circuit Jack Kilby at Texas Instruments demonstrated the first working [[Integrated_circuit|integrated circuit]] on September 12, 1958, etching transistor, resistor and capacitor elements onto a single piece of germanium and wiring them into an oscillator with fine gold wires, a proof of concept that, refined over the following decade, let a radio's entire tuning and amplifying circuitry shrink onto a single chip.[^kilby1958] ### Car radio Fitting a receiver into a moving vehicle raised its own problems, chiefly the electrical noise thrown off by the engine's own ignition system, which had to be filtered or shielded away from the receiver's sensitive front end before car radio could become the reliable factory-fitted option it was by the 1930s. ## Radio telex Teleprinters connected over a radio link, exchanging typed text rather than spoken audio, gave ships, news agencies and, later, diplomatic and military users a way to send substantial written traffic without a human Morse operator at either end, extending the wired [[Telecommunications|telex]] network's reach to anywhere a radio signal could travel. ## Radio navigation Ships and aircraft could find their own position from radio signals alone well before satellite navigation existed, first from simple directional beacons that a receiver's own rotatable [[Antenna_(radio)|antenna]] could be turned to null out, and later from hyperbolic timing systems: LORAN, built by the Massachusetts Institute of Technology's wartime Radiation Laboratory, compared the arrival time of synchronized pulses from pairs of fixed transmitters to fix a receiver's position without it ever transmitting a signal of its own, and covered roughly three-tenths of the Earth's surface by 1946.[^loran] ## FM Edwin Armstrong, already responsible for the regenerative circuit decades earlier, patented a wideband [[Frequency_modulation|frequency-modulation]] system on December 26, 1933, that traded the extra bandwidth FM needs against a dramatic reduction in the static and interference that plague amplitude modulation, at the cost of a receiver and transmitter design substantially different from any AM set already in the field.[^armstrongfm1933] Wide adoption for music broadcasting nonetheless waited for decades, partly because AM's installed base of transmitters and receivers was already enormous and partly because of a late-1940s change in FM's own broadcast band that stranded existing FM receivers on the old frequencies. ### FM in Europe European broadcasters, largely rebuilding their transmitter networks after the Second World War rather than defending a long-established AM audience, adopted [[Very_high_frequency|VHF]] FM broadcasting on the same roughly 87.5 to 108 MHz band still in use today somewhat more uniformly and, in several countries, somewhat earlier relative to their own AM services than in the United States. ## Television Television grew out of radio's own laboratories and companies rather than as an unrelated invention, sharing the same vacuum-tube amplifiers, the same over-the-air [[Radio_wave|transmission]], and often the same manufacturers and broadcasters; mechanical scanning systems of the 1920s gave way through the 1930s to fully electronic cameras and receivers, which is the technology every subsequent television system, including colour, has continued to build on. ### Color television The American National Television System Committee's colour standard, approved by the Federal Communications Commission on December 17, 1953, added colour information on a subcarrier that an existing black-and-white receiver could simply ignore, letting colour and monochrome broadcasting share one channel and one transmission rather than forcing every household to replace its receiver at once.[^ntsc1953] ## Mobile phones Mobile telephony descended from the same two-way [[Radio|radio]] technology that had long served taxis, police and other dispatch fleets, but a true cellular network, handing a call between many small coverage areas instead of broadcasting from one tall, powerful tower, was needed before enough simultaneous users could be served for mobile telephony to become a mass consumer product. Martin Cooper of Motorola made the first call from a handheld cellular telephone on April 3, 1973, on a Manhattan street, using a prototype far larger and heavier than the phones the network he was demonstrating would eventually carry.[^cooper1973] ## Broadcast and copyright Broadcasting a piece of recorded or performed music is, legally, a public performance of it, and American broadcasters resisted paying composers and publishers for that performance for years after ASCAP was formed, in 1914, to collect exactly such fees; when ASCAP's licensing terms became a sticking point in the late 1930s, a group of broadcasting executives meeting at a National Association of Broadcasters convention in Chicago in 1939 founded a rival licensing body, Broadcast Music, Incorporated, open to composers ASCAP had been unwilling to sign.[^bmi1939] ## Regulations of radio stations in the U.S. American radio regulation grew in five distinct steps, each responding to a specific failure of the arrangement before it rather than to any single overall plan. ### Wireless Ship Act of 1910 Congress's first wireless-specific statute, effective June 24, 1910, required that larger passenger vessels leaving American ports carry a wireless set and a skilled operator, a response to near-misses and rescues that had already shown a ship without one was needlessly cut off from help.[^wireless1910] ### Radio Act of 1912 Signed August 13, 1912, months after the Titanic disaster had made the stakes of unregulated, uncoordinated wireless traffic starkly public, this act required stations, including amateur ones, to hold a federal license and to operate on assigned wavelengths, the first general licensing regime American radio had.[^radioact1912] ### The Radio Act of 1927 By the mid-1920s so many broadcasters were competing for so few channels that the 1912 Act's licensing regime had effectively collapsed into interference; the Radio Act of 1927 created the Federal Radio Commission with the explicit power to grant, deny and revoke licenses in the public interest, not merely to record who had already claimed which wavelength.[^radioact1927] ### The Communications Act of 1934 The Communications Act of 1934 replaced the Federal Radio Commission with the Federal Communications Commission and extended federal regulation from radio alone to wired [[Telecommunications|telephone and telegraph]] service as well, on the reasoning that all three were part of a single national communications system that deserved one regulator rather than several.[^commact1934] ### The Telecommunications Act of 1996 The Telecommunications Act of 1996, signed February 8, 1996, rewrote the 1934 Act for an industry the older law had never anticipated, easing long-standing limits on how many stations one owner could hold and opening local telephone markets, cable and broadcasting to competition from companies that had previously been kept out of each other's businesses by regulation.[^telecomact1996] ## Licensed commercial public radio stations Once the 1912 and 1927 Acts had established that a station needed a federal license to operate at all, "licensed commercial station" became the ordinary, unremarkable status of nearly every station with a large audience, KDKA's own 1920 license simply the first of what soon became many thousands of licensed [[AM_broadcasting|AM broadcasting]] stations worldwide, each occupying its own protected slice of a spectrum that, without licensing, every one of history's earlier sections shows sliding quickly into mutual interference. ## Microsims The [[Radar]] article carries a p5.js microsim of pulsed, echo-based ranging, one of the later technologies this history's own regulatory and wartime sections touch without describing in technical depth; it is referenced here only in outline, since its controls and readouts belong on that article's own page, but the underlying idea, sending a wave out and timing or detecting what returns, is the same one this article's radio-navigation section describes LORAN using for position rather than range. *Try:* in that sketch, change the pulse repetition frequency and watch the unambiguous-range ring move; LORAN's wartime designers solved a closely related timing problem, fixing a receiver's position from the arrival times of pulses it never had to send itself, rather than from pulses it sent out and waited to hear echo back. ## Wikipedia : Wikitube **Strict pair:** [Wikipedia](https://en.wikipedia.org/wiki/History_of_radio) : [Wikitube](https://en.wikitube.io/wiki/History_of_radio) Skeleton mirrored at revision 1365293826. Prose, emphasis and the microsims are Wikitube's own. ## See also - [[Guglielmo_Marconi]] - [[Radio]] - [[AM_broadcasting]] - [[Frequency_modulation]] - [[Crystal_radio]] - [[Transistor]] - [[Radar]] ## Footnotes Dates and figures throughout this article are given to the day where a cited source gives one and to the year alone where it does not; none are estimated or rounded beyond what the cited source itself states. ## References [^hertz1888]: Encyclopedia.com, "Heinrich Hertz Produces and Detects Radio Waves in 1888," on Hertz's 1887-1888 spark-transmitter and resonant-loop experiments at Karlsruhe confirming Maxwell's predicted electromagnetic waves. https://www.encyclopedia.com/science/encyclopedias-almanacs-transcripts-and-maps/heinrich-hertz-produces-and-detects-radio-waves-1888 [^bose1895]: Engineering and Technology History Wiki. "Milestones: First Millimeter-wave Communication Experiments by J.C. Bose, 1894-96." https://ethw.org/Milestones:First_Millimeter-wave_Communication_Experiments_by_J.C._Bose,_1894-96 [^marconibio]: The Nobel Foundation. "Guglielmo Marconi – Biographical." NobelPrize.org, 1909 Physics Prize biographical page. https://www.nobelprize.org/prizes/physics/1909/marconi/biographical/ [^transatlantic1901]: Engineering and Technology History Wiki. "Milestones: Reception of Transatlantic Radio Signals, 1901." https://ethw.org/Milestones:Reception_of_Transatlantic_Radio_Signals,_1901 [^fessenden1906]: Broadcasters' Desktop Reference, "What Do We Really Know About Reginald Fessenden?," on the documented December 21, 1906 Brant Rock demonstration and the later, uncorroborated "Christmas Eve" broadcast story. https://www.thebdr.net/what-do-we-really-know-about-reginald-fessenden/ [^kdka1920]: Engineering and Technology History Wiki. "KDKA, First Commercial Radio Station": license granted October 27, 1920; first broadcast November 2, 1920. https://ethw.org/KDKA,_First_Commercial_Radio_Station [^telefunken1903]: Tab-Funkenwerk. "Telefunken AG," on the May 27, 1903 merger of Siemens & Halske's and AEG's wireless interests under government pressure. https://www.tab-funkenwerk.org/history-of-tfk/telefunken-ag/ [^fleming1904]: Engineering and Technology History Wiki. "Milestones: Fleming Valve, 1904." https://ethw.org/Milestones:Fleming_Valve,_1904 [^armstrong1912regen]: Britannica, "Regenerative circuit," on Edwin Armstrong's 1912 feedback circuit and its dual use as receiver and oscillator. https://www.britannica.com/technology/regenerative-circuit [^transistor1947]: Computer History Museum, "1947: Invention of the Point-Contact Transistor," on Bardeen and Brattain's December 16, 1947 demonstration at Bell Telephone Laboratories under William Shockley's group. https://www.computerhistory.org/siliconengine/invention-of-the-point-contact-transistor/ [^kilby1958]: Computer History Museum, "1958: All Semiconductor 'Solid Circuit' is Demonstrated," on Jack Kilby's September 12, 1958 integrated-circuit demonstration at Texas Instruments. https://www.computerhistory.org/siliconengine/all-semiconductor-solid-circuit-is-demonstrated/ [^armstrongfm1933]: PatentYogi, "On December 26, 1933, Edwin Armstrong was granted a patent for a two-path FM radio." https://patentyogi.com/this-day-in-patent-history/this-day-in-patent-history-on-december-26-1933-edwin-armstrong-was-granted-a-patent-for-a-two-path-fm-radio/ [^ntsc1953]: Engineering and Technology History Wiki. "Milestones: Monochrome-Compatible Electronic Color Television, 1946-1953": FCC approval of the NTSC colour standard, December 17, 1953. https://ethw.org/Milestones:Monochrome-Compatible_Electronic_Color_Television,_1946-1953 [^cooper1973]: CNN Business, "50 years ago, he made the first cell phone call," on Martin Cooper's April 3, 1973 Motorola demonstration call. https://www.cnn.com/2023/04/03/tech/cell-phone-turns-50/index.html [^loran]: Engineering and Technology History Wiki. "Milestones: Loran, 1940 - 1946," on the MIT Radiation Laboratory's hyperbolic pulse-timing navigation system. https://ethw.org/Milestones:Loran,_1940_-_1946 [^wireless1910]: Early Radio History (earlyradiohistory.us), text of the Wireless Ship Act, effective June 24, 1910. https://earlyradiohistory.us/1910act.htm [^radioact1912]: Early Radio History (earlyradiohistory.us), text of the Act of August 13, 1912, to Regulate Radio Communication. https://earlyradiohistory.us/1912act.htm [^radioact1927]: Federal Communications Commission, "Radio Act of 1927 [established the Federal Radio Commission]." https://www.fcc.gov/document/radio-act-1927-established-federal-radio-commission [^commact1934]: Britannica, "Communications Act of 1934," on its June 19, 1934 signing and creation of the FCC. https://www.britannica.com/event/Communications-Act-of-1934 [^telecomact1996]: Library of Congress, "President Clinton Signs Telecommunications Act at Library of Congress," February 8, 1996. https://www.loc.gov/item/prn-96-023/president-clinton-signs-telecommunications-act-at-library-of-congress/1996-02-08 [^bmi1939]: BMI (Broadcast Music, Inc.), "BMI History," on its 1939 founding by radio-industry leaders at a National Association of Broadcasters convention as an alternative to ASCAP (founded 1914). https://www.bmi.com/about/history [^empireair]: PBS, "About the Film," *Empire of the Air: The Men Who Made Radio*, directed by Ken Burns, 1991. https://www.pbs.org/kenburns/empire-air/about ## Media and documentaries Ken Burns's documentary *Empire of the Air: The Men Who Made Radio* (PBS, 1991) tells this article's vacuum-tube and patent-litigation history as biography, following Lee De Forest, Edwin Armstrong and David Sarnoff from the Audion through the regenerative circuit and FM to Armstrong's death; it remains the most widely distributed English-language documentary treatment of that particular stretch of the story.[^empireair] ## External links - Early Radio History (earlyradiohistory.us), a compiled archive of primary documents on early American radio regulation and technology: https://earlyradiohistory.us/ - Engineering and Technology History Wiki (ETHW) Milestones programme, individual pages cited above: https://ethw.org/Milestones:Milestones-browse <!-- Hubs: Signal_processing. 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