History of radio

Heinrich Rudolf Hertz (1856–1894) proved the existence of electromagnetic radiation

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][3][4][5]

Between 1886 and 1888 Heinrich Rudolf Hertz published the results of experiments wherein he was able to transmit electromagnetic waves (radio waves) through the air, proving Maxwell's electromagnetic theory.[6][7]

Early experiment demonstrating refraction of microwaves by a paraffin lens by John Ambrose Fleming in 1897

After their discovery many scientists and inventors experimented with transmitting and detecting "Hertzian waves" (it would take almost 20 years for the term "radio" to be universally adopted for this type of electromagnetic radiation).[8] 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.[9][10]

Following Hertz' untimely death in 1894, British physicist and writer Oliver Lodge presented a widely covered lecture on Hertzian waves at the Royal Institution on June 1 of the same year.[11] Lodge focused on the optical qualities of the waves and demonstrated how to transmit and detect them (using an improved variation of French physicist Édouard Branly's detector Lodge named the "coherer").[12] Lodge further expanded on Hertz' experiments showing how these new waves exhibited like light refraction, diffraction, polarization, interference and standing waves,[13] confirming that Hertz' waves and light waves were both forms of Maxwell's electromagnetic waves. During part of the demonstration the waves were sent from the neighboring Clarendon Laboratory building, and received by apparatus in the lecture theater.[14]

Oliver Lodge's 1894 lectures on Hertz demonstrated how to transmit and detect radio waves

After Lodges demonstrations researchers pushed their experiments further down the electromagnetic spectrum towards visible light to further explore the quasioptical nature at these wavelengths.[15] Oliver Lodge and Augusto Righi experimented with 1.5 and 12 GHz microwaves respectively, generated by small metal ball spark resonators.[13] Russian physicist Pyotr Lebedev in 1895 conducted experiments in the 50 GHz 50 (6 millimeter) range.[13] Bengali Indian physicist Jagadish Chandra Bose conducted experiments at wavelengths of 60 GHz (5 millimeter) and invented waveguides, horn antennas, and semiconductor crystal detectors for use in his experiments.[16] He would latter write an essay, "Adrisya Alok" ("Invisible Light") on how in November 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.[17]

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.[18] Among physicist, what were perceived as technical limitations to using these new waves, such as delicate equipment, the need for large amounts of power to transmit over limited ranges, and its similarity to already existent optical light transmitting devices, lead them to a belief that applications were very limited. The Serbian American engineer Nikola Tesla considered Hertzian waves relatively useless for long range transmission since "light" could not transmit further than line of sight.[19] There was speculation that this fog and stormy weather penetrating "invisible light" could be used in maritime applications such as lighthouses,[18] including the London journal The Electrician (December 1895) commenting on Bose's achievements, saying "we may in time see the whole system of coast lighting throughout the navigable world revolutionized by an Indian Bengali scientist working single handed[ly] in our Presidency College Laboratory."[20]

In 1895, adapting the techniques presented in Lodge's published lectures, Russian physicist Alexander Stepanovich Popov built a lightning detector that used a coherer based radio receiver.[21] He presented it to the Russian Physical and Chemical Society on May 7, 1895.

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 a 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.[22] 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,[22] turning what was essentially a laboratory experiment into a useful communication system.[23] 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.[24] This apparatus proved to be the first engineering-complete, commercially successful radio transmission system[25][26][27] and Marconi went on to receive British patent 12039, Improvements in transmitting electrical impulses and signals and in apparatus there-for, in 1896 [28]

Reginald Fessenden (around 1906)

In the late 1890s, Canadian-American inventor Reginald Fessenden came to the conclusion that he could develop a far more efficient system than the spark-gap transmitter and coherer receiver combination.[36][37] 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.[38] While working for the United States Weather Bureau on Cobb Island, Maryland, Fessenden researched using this setup for audio transmissions via radio. By fall of 1900, he successfully transmitted speech over a distance of about 1.6 kilometers (one mile),[39] which appears to have been the first successful audio transmission using radio signals.[40][41] Although successful, the sound transmitted was far too distorted to be commercially practical.[42] According to some sources, notably Fessenden's wife Helen's biography, 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.[43][44]

Around the same time American inventor Lee de Forest experimented with an arc transmitter, which unlike the discontinuous pulses produced by spark transmitters, created steady "continuous wave" signal that could be used for amplitude modulated (AM) audio transmissions. In February 1907 he transmitted electronic telharmonium music from his laboratory station in New York City.[45] This was followed by tests that included, in the fall, Eugenia Farrar singing "I Love You Truly".[46] In July 1907 he made ship-to-shore transmissions by radiotelephone—race reports for the Annual Inter-Lakes Yachting Association (I-LYA) Regatta held on Lake Erie—which were sent from the steam yacht Thelma to his assistant, Frank E. Butler, located in the Fox's Dock Pavilion on South Bass Island.[47]

Telegraphy did not go away on radio. Instead, the degree of automation increased. On land-lines in the 1930s, teletypewriters automated encoding, and were adapted to pulse-code dialing to automate routing, a service called telex. For thirty years, telex was the cheapest form of long-distance communication, because up to 25 telex channels could occupy the same bandwidth as one voice channel. For business and government, it was an advantage that telex directly produced written documents.

Telex systems were adapted to short-wave radio by sending tones over single sideband. CCITT R.44 (the most advanced pure-telex standard) incorporated character-level error detection and retransmission as well as automated encoding and routing. For many years, telex-on-radio (TOR) was the only reliable way to reach some third-world countries. TOR remains reliable, though less-expensive forms of e-mail are displacing it. Many national telecom companies historically ran nearly pure telex networks for their governments, and they ran many of these links over short wave radio.

Documents including maps and photographs went by radiofax, or wireless photoradiogram, invented in 1924 by Richard H. Ranger of Radio Corporation of America (RCA). This method prospered in the mid-20th century and faded late in the century.

One of the first developments in the early 20th century was that aircraft used commercial AM radio stations for navigation, AM stations are still marked on U.S. aviation charts. Radio navigation played an important role during war time, especially in World War II. Before the discovery of the crystal oscillator, radio navigation had many limits.[73] However, as radio technology expanding, navigation is easier to use, and it provides a better position. Although there are many advantages, the radio navigation systems often comes with complex equipment such as the radio compass receiver, compass indicator, or the radar plan position indicator. All of these require users to obtain certain knowledge.

In the 1960s VOR systems became widespread. In the 1970s, LORAN became the premier radio navigation system. Soon, the US Navy experimented with satellite navigation. In 1987, the Global Positioning System (GPS) constellation of satellites was launched.

In 1933, FM radio was patented by inventor Edwin H. Armstrong.[74] FM uses frequency modulation of the radio wave to reduce static and interference from electrical equipment and the atmosphere. In 1937, W1XOJ, the first experimental FM radio station after Armstrong's W2XMN in Alpine, New Jersey, was granted a construction permit by the US Federal Communications Commission (FCC).

In the 1930s, regular analog television broadcasting began in some parts of Europe and North America. By the end of the decade there were roughly 25,000 all-electronic television receivers in existence worldwide, the majority of them in the UK. In the US, Armstrong's FM system was designated by the FCC to transmit and receive television sound.

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.[76] 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.[77] The Advanced Mobile Phone System analog mobile phone system, developed by Bell Labs, was introduced in the Americas in 1978,[78][79][80] 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.

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.[76] 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.[77]

The development of metal–oxide–semiconductor (MOS) large-scale integration (LSI) technology, information theory and cellular networking led to the development of affordable mobile communications.[81] The Advanced Mobile Phone System analog mobile phone system, developed by Bell Labs and introduced in the Americas in 1978,[78][79][80] 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 British government and the state-owned postal services found themselves under massive pressure from the wireless industry (including telegraphy) and early radio adopters to open up to the new medium. In an internal confidential report from February 25, 1924, the Imperial Wireless Telegraphy Committee stated:

"We have been asked 'to consider and advise on the policy to be adopted as regards the Imperial Wireless Services so as to protect and facilitate public interest.' It was impressed upon us that the question was urgent. We did not feel called upon to explore the past or to comment on the delays which have occurred in the building of the Empire Wireless Chain. We concentrated our attention on essential matters, examining and considering the facts and circumstances which have a direct bearing on policy and the condition which safeguard public interests."[82]

When radio was introduced in the early 1920s, many predicted it would kill the phonograph record industry. Radio was a free medium for the public to hear music for which they would normally pay. While some companies saw radio as a new avenue for promotion, others feared it would cut into profits from record sales and live performances. Many record companies would not license their records to be played over the radio, and had their major stars sign agreements that they would not perform on radio broadcasts.[83][84]

Indeed, the music recording industry had a severe drop in profits after the introduction of the radio. For a while, it appeared as though radio was a definite threat to the record industry. Radio ownership grew from two out of five homes in 1931 to four out of five homes in 1938. Meanwhile, record sales fell from $75 million in 1929 to $26 million in 1938 (with a low point of $5 million in 1933), though the economics of the situation were also affected by the Great Depression.[85]

The copyright owners were concerned that they would see no gain from the popularity of radio and the ‘free’ music it provided. What they needed to make this new medium work for them already existed in previous copyright law. The copyright holder for a song had control over all public performances ‘for profit.’ The problem now was proving that the radio industry, which was just figuring out for itself how to make money from advertising and currently offered free music to anyone with a receiver, was making a profit from the songs.

The test case was against Bamberger's Department Store in Newark, New Jersey in 1922. The store was broadcasting music from its store on the radio station WOR. No advertisements were heard, except at the beginning of the broadcast which announced "L. Bamberger and Co., One of America's Great Stores, Newark, New Jersey." It was determined through this and previous cases (such as the lawsuit against Shanley's Restaurant) that Bamberger was using the songs for commercial gain, thus making it a public performance for profit, which meant the copyright owners were due payment.

With this ruling the American Society of Composers, Authors and Publishers (ASCAP) began collecting licensing fees from radio stations in 1923. The beginning sum was $250 for all music protected under ASCAP, but for larger stations the price soon ballooned to $5,000. Edward Samuels reports in his book The Illustrated Story of Copyright that "radio and TV licensing represents the single greatest source of revenue for ASCAP and its composers […] and [a]n average member of ASCAP gets about $150–$200 per work per year, or about $5,000-$6,000 for all of a member's compositions." Not long after the Bamberger ruling, ASCAP had to once again defend their right to charge fees, in 1924. The Dill Radio Bill would have allowed radio stations to play music without paying and licensing fees to ASCAP or any other music-licensing corporations. The bill did not pass.[86]

Around 1920, radio broadcasting started to get popular. The Brox Sisters, a popular singing group, gathered around the radio at the time.

The question of the 'first' publicly targeted licensed radio station in the U.S. has more than one answer and depends on semantics. Settlement of this 'first' question may hang largely upon what constitutes 'regular' programming

• It is commonly attributed to KDKA in Pittsburgh, Pennsylvania, which in October 1920 received its license and went on the air as the first US licensed commercial broadcasting station on November 2, 1920, with the presidential election results as its inaugural show, but was not broadcasting daily until 1921. (Their engineer Frank Conrad had been broadcasting from on the two call sign signals of 8XK and 8YK since 1916.) Technically, KDKA was the first of several already-extant stations to receive a 'limited commercial' license.[92]
• On February 17, 1919, station 9XM at the University of Wisconsin in Madison broadcast human speech to the public at large. 9XM was first experimentally licensed in 1914, began regular Morse code transmissions in 1916, and its first music broadcast in 1917. Regularly scheduled broadcasts of voice and music began in January 1921. That station is still on the air today as WHA.[93]
• On August 20, 1920, 8MK, began broadcasting daily and was later claimed by famed inventor Lee de Forest as the first commercial station. 8MK was licensed to a teenager, Michael DeLisle Lyons, and financed by E. W. Scripps. In 1921 8MK changed to WBL and then to WWJ in 1922, in Detroit. It has carried a regular schedule of programming to the present and also broadcast the 1920 presidential election returns just as KDKA did.[94] Inventor Lee de Forest claims to have been present during 8MK's earliest broadcasts, since the station was using a transmitter sold by his company.[95]
• The first station to receive a commercial license was WBZ, then in Springfield, Massachusetts. Lists provided to the Boston Globe by the U.S. Department of Commerce showed that WBZ received its commercial license on 15 September 1921; another Westinghouse station, WJZ, then in Newark, New Jersey, received its commercial license on November 7, the same day as KDKA did.[96] What separates WJZ and WBZ from KDKA is the fact that neither of the former stations remain in their original city of license, whereas KDKA has remained in Pittsburgh for its entire existence.
• 2XG: Launched by Lee de Forest in the Highbridge section of New York City, that station began daily broadcasts in 1916.[97] Like most experimental radio stations, however, it had to go off the air when the U.S. entered World War I in 1917, and did not return to the air.
• 1XE: Launched by Harold J. Power in Medford, Massachusetts, 1XE was an experimental station that started broadcasting in 1917. It had to go off the air during World War I, but started up again after the war, and began regular voice and music broadcasts in 1919. However, the station did not receive its commercial license, becoming WGI, until 1922.[98]
• WWV, the U.S. Government time service, which was believed to have started 6 months before KDKA in Washington, D.C. but in 1966 was transferred to Ft. Collins, Colorado.[99]
• WRUC, the Wireless Radio Union College, located on Union College in Schenectady, New York; was launched as W2XQ [100]
• KQV, one of Pittsburgh's five original AM stations, signed on as amateur station "8ZAE" on November 19, 1919, but did not receive a commercial license until January 9, 1922.

Histories

• History of electrical engineering
• History of electromagnetic theory
• History of electromagnetic spectrum
• History of amateur radio
• History of broadcasting
• History of music
• History of physics
• History of podcasting
• History of radar
• History of science and technology
• History of telecommunication
• History of television
• History of videotelephony

General

Many contributed to wireless. Individuals that helped to further the science include, among others:

Categories

• Empire of the Air: The Men Who Made Radio (1992) by Ken Burns, PBS documentary based on the 1991 book, Empire of the Air: The Men Who Made Radio by Tom Lewis, 1st ed., New York : E. Burlingame Books, ISBN 0060182156