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History of radio

From Wikipedia, the free encyclopedia

For the controversy about who invented radio, see Invention of radio.

The early history of radio is the history of technology that produces and uses radio instruments that use radio waves. Within the timeline of radio, many people contributed theory and inventions in what became radio. Radio development began as “wireless telegraphy“. Later radio history increasingly involves matters of broadcasting.

Summary

This article may need to be cleaned up. It has been merged from Radio#History.

Invention

Main article: Invention of radio

The idea of wireless communication predates the discovery of “radio” with experiments in “wireless telegraphy” via inductive and capacitive induction and transmission through the ground, water, and even train tracks from the 1830s on. James Clerk Maxwell showed in theoretical and mathematical form in 1864 that electromagnetic waves could propagate through free space.^[1]^[2] It is likely that the first intentional transmission of a signal by means of electromagnetic waves was performed in an experiment by David Edward Hughes around 1880, although this was considered to be induction at the time. In 1888 Heinrich Rudolf Hertz was able to conclusively prove transmitted airborne electromagnetic waves in an experiment confirming Maxwell’s theory of electromagnetism.

Electrical engineer/inventor Guglielmo Marconi with the spark-gap transmitter (right) and coherer receiver (left) he used in some of his first long distance radiotelegraphy transmissions during the 1890s.

After the discovery of these “Hertzian waves” (it would take almost 20 years for the term “radio” to be universally adopted for this type of electromagnetic radiation)^[3] many scientists and inventors experimented with transmitting and detecting Hertzian waves. Maxwell’s theory showing that light and Hertzian electromagnetic waves were the same phenomenon at different wavelengths led “Maxwellian” scientists such as John Perry, Frederick Thomas Trouton and Alexander Trotter to assume they would be analogous to optical light.^[4]^[5] The Serbian American engineer Nikola Tesla (who proposed a wireless power/communication earth conduction system similar to radio in 1893)^[6]^[7]^[8] considered Hertzian waves relatively useless for his system since “light” could not transmit further than line of sight.^[9] In 1892 the physicist William Crookes wrote on the possibilities of wireless telegraphy based on Hertzian waves.^[10] Others, such as Sir Oliver Lodge, Jagadish Chandra Bose, and Alexander Popov were involved in the development of components and theory involved with the transmission and reception of airborne electromagnetic waves for their own theoretical work.

Over several years starting in 1894 the Italian inventor Guglielmo Marconi built the first engineering complete, commercially successful wireless telegraphy system based on airborne Hertzian waves (radio transmission).^[11] Marconi demonstrated the application of radio in military and marine communications and started a company for the development and propagation of radio communication services and equipment.

19th century

The meaning and usage of the word “radio” has developed in parallel with developments within the field of communications and can be seen to have three distinct phases: electromagnetic waves and experimentation; wireless communication and technical development; and radio broadcasting and commercialization.

James Clerk Maxwell (1831-1879), the founder of electromagnetism theory

In an 1864 presentation, published in 1865, James Clerk Maxwell proposed theories of electromagnetism, with mathematical proofs, that showed that light and predicted that radio and x-rays were all types of electromagnetic waves propagating through free space.^[1]^[2]^[12]^[13]^[14] In 1886–88 Heinrich Rudolf Hertz conducted a series of experiments that proved the existence of Maxwell’s electromagnetic waves, using a frequency in what would later be called the radio spectrum. Many individuals—inventors, engineers, developers and businessmen—constructed systems based on their own understanding of these and other phenomena, some predating Maxwell and Hertz’s discoveries. Thus “wireless telegraphy” and radio wave-based systems can be attributed to multiple “inventors”. Development from a laboratory demonstration to a commercial entity spanned several decades and required the efforts of many practitioners.

In 1878, David E. Hughes noticed that sparks could be heard in a telephone receiver when experimenting with his carbon microphone. He developed this carbon-based detector further and eventually could detect signals over a few hundred yards. He demonstrated his discovery to the Royal Society in 1880, but was told it was merely induction, and therefore abandoned further research. Thomas Edison came across the electromagnetic phenomenon while experimenting with a telegraph at Menlo Park. He noted an unexplained transmission effect while experimenting with a telegraph. He referred to this as etheric force in an announcement on November 28, 1875. Elihu Thomson published his findings on Edison’s new “force”, again attributing it to induction, an explanation that Edison accepted. Edison would go on the next year to take out U.S. Patent 465,971 on a system of electrical wireless communication between ships based on electrostatic coupling using the water and elevated terminals. Although this was not a radio system, Edison would sell his patent rights to his friend Guglielmo Marconi at the Marconi Company in 1903, rather than another interested party who might end up working against Marconi’s interests.^[15]

Hertzian waves

Heinrich Rudolf Hertz (1856-1894) discovered an important step in the process of radio development called the Hertzian waves.

Between 1886 and 1888 Heinrich Rudolf Hertz published the results of his experiments wherein he was able to transmit electromagnetic waves (radio waves) through the air, proving Maxwell’s electromagnetic theory.^[16]^[17] Thus, given Hertz comprehensive discoveries, radio waves were referred to as “Hertzian waves”.^[18] Between 1890 and 1892 physicists such as John Perry, Frederick Thomas Trouton and William Crookes proposed electromagnetic or Hertzian waves as a navigation aid or means of communication, with Crookes writing on the possibilities of wireless telegraphy based on Hertzian waves in 1892.^[10]

In a lecture on the work of Hertz, shortly after his death, Professors Oliver Lodge and Alexander Muirhead presented a widely covered lecture on Hertzian (radio) waves in the lecture theater of the Oxford University Museum of Natural History on August 14, 1894. Lodge focused on the optical qualities of the waves and demonstrated how to transmit, reflect, and detect them (using an improved variation of French physicist Édouard Branly‘s detector Lodge named the “coherer“).^[19] During part of the demonstration radio waves were sent from the neighboring Clarendon Laboratory building, and received by apparatus in the lecture theater.^[20]

Building on the work of Lodge,^[21] the Bengali Indian physicist Jagadish Chandra Bose further explored the optical nature these waves. He conducted his experiments using very short wavelengths (close to visible light in the microwave range) which allowed his test equipment, antennas, reflectors, and prisms, to be much smaller. He published the paper “On polarisation of electric rays by double-refracting crystals”^[22] in May 1895 followed by a second paper sent to the Royal Society of London in October 1895.^{[clarification needed]}^{[full citation needed]} The London journal The Electrician (December 1895) noted: “Should Professor Bose succeed in perfecting and patenting his ‘Coherer’, we may in time see the whole system of coast lighting throughout the navigable world revolutionised by an Indian Bengali scientist working single handed[ly] in our Presidency College Laboratory.” Bose would latter write an essay, “Adrisya Alok” (“Invisible Light”) on how during 1895 he conducted a public demonstration at the Town Hall of Kolkata, India using millimeter-range-wavelength microwaves to trigger detectors that ignited gunpowder and rang a bell at a distance.^[23]

In 1895, conducting experiments along the lines of Hertz’s research, Alexander Stepanovich Popov built his first radio receiver, which contained a coherer. Popov further refined his invention as a lightning detector and presented to the Russian Physical and Chemical Society on May 7, 1895. A depiction of the lightning detector was printed in the Journal of the Russian Physical and Chemical Society the same year (publication of the minutes 15/201 of this session – December issue of the journal RPCS^[24]). An earlier description of the device was given by Dmitry Aleksandrovich Lachinov in July 1895 in the second edition of his course “Fundamentals of Meteorology and Climatology”, which was the first such course in Russia.^[25]^[26] Popov’s receiver was created on the improved basis of Lodge’s receiver, and originally intended for reproduction of its experiments.

Guglielmo Marconi

British Post Office engineers inspect Guglielmo Marconi’s wireless telegraphy (radio) equipment in 1897.

In 1894, the young Italian inventor Guglielmo Marconi began working on the idea of building long distance wireless transmission systems based on the use of Hertzian waves (radio waves), a line of inquiry that he noted other inventors did not seem to be pursuing.^[11] Marconi read through the literature and used the ideas of others who were experimenting with radio waves but did a great deal to develop devices such as portable transmitters and receiver systems that could work over long distances,^[11] turning what was essentially a laboratory experiment into a useful communication system.^[27] By August 1895, Marconi was field testing his system but even with improvements he was only able to transmit signals up to one-half mile, a distance Oliver Lodge had predicted in 1894 as the maximum transmission distance for radio waves. Marconi raised the height of his antenna and hit upon the idea of grounding his transmitter and receiver. With these improvements the system was capable of transmitting signals up to 2 miles (3.2 km) and over hills.^[28] Marconi’s experimental apparatus proved to be the first engineering-complete, commercially successful radio transmission system.^[29]^[30]^[31] Marconi’s apparatus is also credited with saving the 700 people who survived the tragic Titanic disaster.^[32]

In 1896, Marconi was awarded British patent 12039, Improvements in transmitting electrical impulses and signals and in apparatus there-for, the first patent ever issued for a Hertzian wave (radio wave) base wireless telegraphic system.^[33] In 1897, he established a radio station on the Isle of Wight, England. Marconi opened his “wireless” factory in the former silk-works at Hall Street, Chelmsford, England, in 1898, employing around 60 people. Shortly after the 1900s, Marconi held the patent rights for radio. Marconi would go on to win the Nobel Prize in Physics in 1909^[34] and be more successful than any other inventor in his ability to commercialize radio and its associated equipment into a global business.^[11] In the US some of his subsequent patented refinements (but not his original radio patent) would be overturned in a 1935 court case (upheld by the US Supreme Court in 1943).^[35]

20th century

Through the end of the 19th century Canadian-American inventor Reginald Fessenden worked on the possibility of making audio radio transmissions, in contrast to the early spark-gap transmissions that could only transmit Morse code messages.^[36] To this end he worked on developing a high-speed alternator (referred to as “an alternating-current dynamo”) that generated “pure sine waves” and produced “a continuous train of radiant waves of substantially uniform strength”, or, in modern terminology, a continuous-wave (CW) transmitter.^[37] While working for the United States Weather Bureau on Cobb Island, Maryland, Fessenden began research on audio transmissions via radio. Because he did not yet have a continuous-wave transmitter, initially he worked with an experimental “high-frequency spark” transmitter, taking advantage of the fact that the higher the spark rate, the closer a spark-gap transmission comes to producing continuous waves. He later reported that, in the fall of 1900, he successfully transmitted speech over a distance of about 1.6 kilometers (one mile),^[38] which appears to have been the first successful audio transmission using radio signals.^[39]^[40] Although successful, the sound transmitted was far too distorted to be commercially practical.^[41] On Christmas Eve 1906, Fessenden used a synchronous rotary-spark transmitter for the first radio program broadcast, from Ocean Bluff-Brant Rock, Massachusetts. Ships at sea heard a broadcast that included Fessenden playing O Holy Night on the violin and reading a passage from the Bible.^[42] This was, for all intents and purposes, the first transmission of what is now known as amplitude modulation or AM radio.

In June 1912 Marconi opened the world’s first purpose-built radio factory at New Street Works in Chelmsford, England.

The first radio news program was broadcast August 31, 1920 by station 8MK in Detroit, Michigan, which survives today as all-news format station WWJ under ownership of the CBS network. The first college radio station began broadcasting on October 14, 1920 from Union College, Schenectady, New York under the personal call letters of Wendell King, an African-American student at the school.^[42]

That month 2ADD (renamed WRUC in 1947), aired what is believed to be the first public entertainment broadcast in the United States, a series of Thursday night concerts initially heard within a 100-mile (160 km) radius and later for a 1,000-mile (1,600 km) radius. In November 1920, it aired the first broadcast of a sporting event.^[42]^[43] At 9 pm on August 27, 1920, Sociedad Radio Argentina aired a live performance of Richard Wagner’s opera Parsifal from the Coliseo Theater in downtown Buenos Aires. Only about twenty homes in the city had receivers to tune in this radio program. Meanwhile, regular entertainment broadcasts commenced in 1922 from the Marconi Research Centre at Writtle, England.

Sports broadcasting began at this time as well, including the college football on radio broadcast of a 1921 West Virginia vs. Pittsburgh football game.^[44]

One of the first developments in the early 20th century was that aircraft used commercial AM radio stations for navigation. This continued until the early 1960s when VOR systems became widespread.^[45] In the early 1930s, single sideband and frequency modulation were invented by amateur radio operators. By the end of the decade, they were established commercial modes. Radio was used to transmit pictures visible as television as early as the 1920s. Commercial television transmissions started in North America and Europe in the 1940s.

In 1947 AT&T commercialized the Mobile Telephone Service. From its start in St. Louis in 1946, AT&T then introduced Mobile Telephone Service to one hundred towns and highway corridors by 1948. Mobile Telephone Service was a rarity with only 5,000 customers placing about 30,000 calls each week. Because only three radio channels were available, only three customers in any given city could make mobile telephone calls at one time.^[46] Mobile Telephone Service was expensive, costing US$15 per month, plus $0.30–0.40 per local call, equivalent to (in 2012 US dollars) about $176 per month and $3.50–4.75 per call.^[47] The Advanced Mobile Phone System analog mobile phone system, developed by Bell Labs, was introduced in the Americas in 1978,^[48]^[49]^[50] gave much more capacity. It was the primary analog mobile phone system in North America (and other locales) through the 1980s and into the 2000s.

The Regency TR-1, which used Texas Instruments‘ NPN transistors, was the world’s first commercially produced transistor radio in 1954.

Following development of transistor technology, bipolar junction transistors led to the development of the transistor radio. In 1954, the Regency company introduced a pocket transistor radio, the TR-1, powered by a “standard 22.5 V Battery.” In 1955, the newly formed Sony company introduced its first transistorized radio, the TR-55.^[51] It was small enough to fit in a vest pocket, powered by a small battery. It was durable, because it had no vacuum tubes to burn out. In 1957, Sony introduced the TR-63, the first mass-produced transistor radio, leading to the mass-market penetration of transistor radios.^[52] Over the next 20 years, transistors replaced tubes almost completely except for high-power transmitters.

By the mid-1960s, the Radio Corporation of America (RCA) were using metal–oxide–semiconductor field-effect transistors (MOSFETs) in their consumer products, including FM radio, television and amplifiers.^[53] Metal–oxide–semiconductor (MOS) large-scale integration (LSI) provided a practical and economic solution for radio technology, and was used in mobile radio systems by the early 1970s.^[54]

By 1963, color television was being broadcast commercially (though not all broadcasts or programs were in color), and the first (radio) communication satellite, Telstar, was launched. In the 1970s, LORAN became the premier radio navigation system. Soon, the U.S. Navy experimented with satellite navigation, culminating in the launch of the Global Positioning System (GPS) constellation in 1987.

Wavelength (meters) vs. frequency (kilocycles, kilohertz)

In early radio, and to a limited extent much later, the transmission signal of the radio station was specified in meters, referring to the wavelength, the length of the radio wave. This is the origin of the terms long wave, medium wave, and short wave radio.^[55] Portions of the radio spectrum reserved for specific purposes were often referred to by wavelength: the 40-meter band, used for amateur radio, for example. The relation between wavelength and frequency is reciprocal: the higher the frequency, the shorter the wave, and vice versa.

As equipment progressed, precise frequency control became possible; early stations often did not have a precise frequency, as it was affected by the temperature of the equipment, among other factors. Identifying a radio signal by its frequency rather than its length proved much more practical and useful, and starting in the 1920s this became the usual method of identifying a signal, especially in the United States. Frequencies specified in number of cycles per second (kilocycles, megacycles) were replaced by the more specific designation of hertz (cycles per second) about 1965.

Digital era

In the 1970s, the U.S. long-distance telephone network began to transition towards a digital telephone network, employing digital radios for many of its links. The transition towards digital telecommunication networks was enabled by mixed-signal MOS integrated circuit chips using switched-capacitor (SC) and pulse-code modulation (PCM) technologies.^[56]^[57] In the late 1980s, Asad Ali Abidi at UCLA developed RF CMOS (radio-frequency CMOS),^[58] a radio transceiver system on a mixed-signal MOS IC chip,^[59] which enabled the introduction of digital signal processing in wireless communications.^[60]

In 1990, discrete cosine transform (DCT) video coding standards enabled digital television (DTV) transmission in both standard-definition television (SDTV) and high-definition television (HDTV) formats.^[61] In the early 1990s, amateur radio experimenters began to use personal computers with audio cards to process radio signals.

In the 1990s, the wireless revolution began,^[62]^[63]^[64] with the advent of digital wireless networks.^[65] It began with the introduction of digital cellular mobile networks, enabled by LDMOS (power MOSFET) RF power amplifiers and CMOS RF circuits.^[65]^[66]^[58] In 1994, the U.S. Army and DARPA launched an aggressive, successful project to construct a software-defined radio that can be programmed to be virtually any radio by changing its software program.

Digital transmissions began to be applied to commercial broadcasting in the late 1990s. In 1995, Digital Audio Broadcasting (DAB), a digital radio standard, launched in Europe. ISDB-S, a Japanese digital television standard, was launched in 1996, and was later followed by the ISDB-T digital radio standard.

Start of the 20th century

Around the start of the 20th century, the Slaby-Arco wireless system was developed by Adolf Slaby and Georg von Arco.^[67] In 1900, Reginald Fessenden made a weak transmission of voice over the airwaves. In 1901, Marconi conducted the first successful transatlantic experimental radio communications. In 1907, Marconi established the first commercial transatlantic radio communications service, between Clifden, Ireland and Glace Bay, Nova Scotia.

Donald Manson working as an employee of the Marconi Company (England, 1906)

Julio Cervera Baviera

Julio Cervera Baviera developed radio in Spain around 1902.^[68]^[69] Cervera Baviera obtained patents in England, Germany, Belgium, and Spain. In May–June 1899, Cervera had, with the blessing of the Spanish Army, visited Marconi’s radiotelegraphic installations on the English Channel, and worked to develop his own system. He began collaborating with Marconi on resolving the problem of a wireless communication system, obtaining some patents by the end of 1899. Cervera, who had worked with Marconi and his assistant George Kemp in 1899, resolved the difficulties of wireless telegraph and obtained his first patents prior to the end of that year. On March 22, 1902, Cervera founded the Spanish Wireless Telegraph and Telephone Corporation and brought to his corporation the patents he had obtained in Spain, Belgium, Germany and England.^[70] He established the second and third regular radiotelegraph service in the history of the world in 1901 and 1902 by maintaining regular transmissions between Tarifa and Ceuta (across the Straits of Gibraltar) for three consecutive months, and between Javea (Cabo de la Nao) and Ibiza (Cabo Pelado). This is after Marconi established the radiotelegraphic service between the Isle of Wight and Bournemouth in 1898. In 1906, Domenico Mazzotto wrote: “In Spain the Minister of War has applied the system perfected by the commander of military engineering, Julio Cervera Baviera (English patent No. 20084 (1899)).”^[71] Cervera thus achieved some success in this field, but his radiotelegraphic activities ceased suddenly, the reasons for which are unclear to this day.^[72]

British Marconi

Using various patents, the British Marconi company was established in 1897 by Guglielmo Marconi and began communication between coast radio stations and ships at sea.^[73] A year after, in 1898, they successfully introduced their first radio station in Chelmsford. This company, along with its subsidiaries Canadian Marconi and American Marconi, had a stranglehold on ship-to-shore communication. It operated much the way American Telephone and Telegraph operated until 1983, owning all of its equipment and refusing to communicate with non-Marconi equipped ships. Many inventions improved the quality of radio, and amateurs experimented with uses of radio, thus planting the first seeds of broadcasting.

Telefunken

The company Telefunken was founded on May 27, 1903, as “Telefunken society for wireless telefon” of Siemens & Halske (S & H) and the Allgemeine Elektrizitäts-Gesellschaft (General Electricity Company) as joint undertakings for radio engineering in Berlin.^[74] It continued as a joint venture of AEG and Siemens AG, until Siemens left in 1941. In 1911, Kaiser Wilhelm II sent Telefunken engineers to West Sayville, New York to erect three 600-foot (180-m) radio towers there. Nikola Tesla assisted in the construction. A similar station was erected in Nauen, creating the only wireless communication between North America and Europe.

Reginald Fessenden

The invention of amplitude-modulated (AM) radio, so that more than one station can send signals (as opposed to spark-gap radio, where one transmitter covers the entire bandwidth of the spectrum) is attributed to Reginald Fessenden and Lee de Forest. According to some sources, notably Fessenden’s wife Helen’s biography,^[75] on Christmas Eve 1906, Reginald Fessenden used an Alexanderson alternator and rotary spark-gap transmitter to make the first radio audio broadcast, from Brant Rock, Massachusetts. Ships at sea heard a broadcast that included Fessenden playing O Holy Night on the violin and reading a passage from the Bible. However, Fessenden himself never mentioned that date: rather, he wrote of experiments with voice as early as 1902.^[76] And some of his experiments with voice and music, which occurred in mid-to-late December 1906, were reported in the American Telephone Journal.^[77]

Later 20th-century developments

Following development of transistor technology, bipolar junction transistors led to the development of the transistor radio. In 1954, Regency introduced a pocket transistor radio, the TR-1, powered by a “standard 22.5V Battery”. In 1955, the newly formed Sony company introduced its first transistorized radio, the TR-55.^[51] In 1957, Sony introduced the TR-63, the first mass-produced transistor radio, leading to the mass-market penetration of transistor radios.^[52] It was small enough to fit in a vest pocket, and able to be powered by a small battery. It was durable, because there were no tubes to burn out. Over the next twenty years, transistors displaced tubes almost completely except for picture tubes and very high power or very high frequency uses.

In the early 1960s, VOR systems finally became widespread for aircraft navigation; before that, aircraft used commercial AM radio stations for navigation. (AM stations are still marked on U.S. aviation charts).

By the mid-1960s, the Radio Corporatio

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