Invention_of

Within the timeline of radio, several people were involved in the invention of radio and there were many key inventions in what became the modern systems of wireless.¹ Radio development began as "wireless telegraphy".¹ Closely related, radio was developed along with two other key inventions, the telegraph and the telephone.¹ During the early development of wireless technology and long after its wide use, disputes persisted as to who could claim credit for the invention of radio. The matter was important for economic, political and nationalistic reasons.

Physics of radio

Several different electrical, magnetic, or electromagnetic physical phenomena can be used to transmit signals over a distance without intervening wires. The various methods for wireless signal transmissions include:

All these physical phenomena have been tested for purposes of communication. Early researchers may not have understood or disclosed which physical effects were responsible for transmitting signals. Early experiments used the existing theories of the movement of charged particles through an electrical conductor. There was no theory of electromagnetic wave propagation to guide experiments before Maxwell's treatise and its verification by Hertz and others.

Capacitive and inductive coupling systems today are used only for short-range special purpose systems. The physical phenomenon used generally today for long-distance wireless communications involves the use of modulation of electromagnetic waves, which is radio.

Radio antennas radiate electromagnetic waves that can reach the receiver either by ground-wave propagation or by refraction from the ionosphere, known as sky-wave propagation. The ground-wave component is the portion of the radiated electromagnetic wave that propagates close to the earth's surface. It has both direct-wave and ground-reflected components. The direct-wave is limited only by the distance from the transmitter to the horizon plus a distance added by diffraction around the curvature of the earth. The ground-reflected portion of the radiated wave reaches the receiving antenna after being reflected from the earth's surface. A portion of the ground-wave energy radiated by the antenna may also be guided by the earth's surface as a ground-hugging surface wave.

Early theories and experiments

Several scientists speculated that light might be some kind of wave connected with electricity or magnetism. Around 1830 Francesco Zantedeschi suggested a connection between light, electricity, and magnetism .³ In 1832 Joseph Henry performed experiments detecting electromagnetic effects over a distance of 200 feet and postulated the existence of electromagnetic waves. In 1846 Michael Faraday speculated that light was a wave disturbance in a force field".⁴

Complete theory of electromagnetism

Based on the experimental work of Faraday and other physicists, James Clerk Maxwell developed the theory of electromagnetism that predicted the existence of electromagnetic waves. He did not transmit or receive radio waves.

Innovations and laboratory experiments

Hughes

In 1879, during experiments with his induction balance, David E. Hughes transmitted signals which he attributed to electromagnetic waves. Hughes' contemporaries claimed that the detected effects were due to electromagnetic induction. Hughes used his apparatus to transmit Morse code using a transmitter controlled by clockwork.

Hertz

Heinrich Rudolf Hertz was the experimental physicist who confirmed Maxwell's work in the laboratory.⁵ Hertz, though, did not devise a system for actual general use nor describe the application of the technology. From 1886 to 1888 inclusive, in his UHF experiments, he showed that the properties of radio waves were consistent with Maxwell’s electromagnetic theory. He demonstrated that radio radiation had all the properties of waves (now called electromagnetic radiation), and discovered that the electromagnetic equations could be reformulated into a partial differential equation called the wave equation.

Hertz’s setup for a source and detector of radio waves (then called Hertzian waves⁶ or Hertz waves in his honor), comprised a primitive radio system capable of transmitting and receiving radio waves through free space.⁷ His transmitter was not particularly efficient and was limited in power output.

Hertz used the damped oscillating currents in a dipole antenna, triggered by a high-voltage electrical capacitive spark discharge, as his source of radio waves. His detector in some experiments was another dipole antenna connected to a narrow spark gap. A small spark in this gap signified detection of the radio waves. When he added cylindrical reflectors behind his dipole antennas, Hertz could detect radio waves about 20 metres from the transmitter in his laboratory. He did not try to transmit further because he wanted to prove Electromagnetism|electromagnetic theory, not to develop wireless communications.

Hertz seemed uninterested in the practical importance of his experiments. He stated that "It's of no use whatsoever ... this is just an experiment that proves Maestro Maxwell was right - we just have these mysterious electromagnetic waves that we cannot see with the naked eye. But they are there."⁸

Asked about the ramifications of his discoveries, Hertz replied, "Nothing, I guess." Hertz also stated, "I do not think that the wireless waves I have discovered will have any practical application."⁸ Hertz died in 1894, so the art of radio was left to others to implement into a practical useful form. His discoveries would later be taken up by entrepreneurs looking to make their fortunes.

Tesla

Around July 1891, Nikola Tesla constructed various apparatus that produced between 15,000 to 18,000 cycles per second. Transmission and radiation of radio frequency energy was a feature exhibited in the experiments by Tesla which he proposed might be used for the telecommunication of information.⁹¹⁰

After 1892, Tesla delivered a widely reported presentation before the Institution of Electrical Engineers of London in which he suggested that messages could be transmitted without wires. Later, a variety of Tesla's radio frequency systems were demonstrated during another widely known lecture, presented to meetings of the National Electric Light Association in St. Louis, Missouri and the Franklin Institute in Philadelphia. According to the IEEE, "the apparatus that he employed contained all the elements of spark and continuous wave that were incorporated into radio transmitters before the advent of the vacuum tube".¹¹ However, "he almost perversely rejected the notion of transmission by Hertzian waves, which he considered to be wasteful of energy."¹¹¹²¹³

Bose

In November 1894, the Bengali Indian physicist, Jagadish Chandra Bose, demonstrated publicly the use of radio waves in Calcutta, but he was not interested in patenting his work.¹⁴ In 1894, Bose ignited gunpowder and rang a bell at a distance using electromagnetic waves, showing independently that communication signals can be sent without using wires. In 1896, the Daily Chronicle of England reported on his UHF experiments: "The inventor (J.C. Bose) has transmitted signals to a distance of nearly a mile and herein lies the first and obvious and exceedingly valuable application of this new theoretical marvel."

Bose was not interested in the commercial applications of the experiment's transmitter. He did not try to file patent protection for sending signals. In 1899, Bose announced the development of a "iron-mercury-iron coherer with telephone detector" in a paper presented at the Royal Society, London.¹⁵ Later he received U.S. Patent 755,840 , "Detector for electrical disturbances" (1904), for a specific electromagnetic receiver.

Edison

In 1885, T. A. Edison used a vibrator magnet for induction transmission. In 1888, he deployed a system of signaling on the Lehigh Valley Railroad. In 1892, Edison patented a method using capacitive coupling between elevated terminals (U.S. Patent 465,971 ).

Early Commercial exploitation

Tesla

Radio frequency generation

The electromechanical engineer Nikola Tesla, who has been called called the father of wireless telegraphy,¹⁷ was one of the first to patent a means to reliably produce radio frequency waves. Tesla's U.S. Patent 447,920 , "Method of Operating Arc-Lamps" (March 10, 1891), describes an alternator that produced high-frequency (for that time period) current of around 10,000 hertz. His innovation was suppression of the sound produced by arc lamps that were operated on alternating or pulsating current by using frequencies beyond the range of human hearing.

Continued research and patents

Early on in his research Tesla used his high voltage resonance transformer — the Tesla coil¹⁸ — in radio-wave propagation experiments. The aerial consisted of a top-loaded electrical conductor that was connected to a high-voltage terminal of the transformer. The opposing high-voltage terminal was grounded. The secondary winding was driven by a primary circuit consisting of a few turns of heavy wire, a capacitor bank, a circuit controller, and a power supply transformer. The launching structure could be operated as a electromagnetic radiator (or "Hertz wave antenna") or a large scale electromagnetic resonator.

Between 1895 and 1899, Tesla claimed to have received wireless signals transmitted over long distances although there is no independent evidence to support this.¹⁹ After 1896, the transmitter consisted of an RF alternator and produced undamped (or continuous) waves in the neighborhood of 50,000 Hertz.²⁰ The receiver consisted of a powerful electromagnet, two large condensers, and a taut steel wire. The wire was placed within the magnetic field, and in conjunction with the condensers formed a tuned circuit.²¹²²

After a while he began to favor another technique that he called the “disturbed charge of ground and air method.” Tesla's wireless system used the same basic apparatus, however instead of using electromagnetic space waves, he claimed that the energy was carried by the resonation of electrical currents through the earth and along with accompanying surface waves. In one form of the system he claimed that the ‘return’ path closing the circuit is an electrical current flow established between two elevated terminals, one belonging to the transmitter and the other the receiver. These consist of currents flowing through ionized air. Once again in Tesla's own words,

Popov

Beginning in the early 1890s, Alexander Stepanovich Popov conducted experiments along the lines of Hertz's research. In 1894 he built his first radio receiver, which contained a coherer. Further refined as a lightning detector, he presented it to the Russian Physical and Chemical Society on May 7, 1895 — the day has been celebrated in the Russian Federation as "Radio Day". The paper on his findings was published the same year (December 15 1895). Popov had recorded, at the end of 1895, that he was hoping for distant signaling with radio waves.²⁵

In 1900 a radio station was established under Popov's instructions on Hogland island (Suursaari) to provide two-way communication by wireless telegraphy between the Russian naval base and the crew of the battleship General-Admiral Apraksin. By February 5 messages were being received reliably. The wireless messages were relayed to Hogland Island by a station some 25 miles away at Kymi (nowadays Kotka) on the Finnish coast.

Marconi

Early years

Guglielmo Marconi, who has been called the father of radio,²⁶ is said to have read about the experiments that Hertz did in the 1880s while he was on vacation in 1894 and about Tesla's work. It was at this time that Marconi began to understand that radio waves could be used for wireless communications.²⁷

Marconi's early apparatus was a development of Hertz’s laboratory apparatus into a system designed for communications purposes. At first Marconi used a transmitter to ring a bell in a receiver in his attic laboratory. He then moved his experiments out-of-doors on the family estate near Bologna, Italy, to communicate further. He replaced Hertz’s vertical dipole with a vertical wire topped by a metal sheet, with an opposing terminal connected to the ground. On the receiver side, Marconi replaced the spark gap with a metal powder coherer, a detector developed by Edouard Branly and other experimenters. Marconi transmitted radio signals for about a mile at the end of 1895.²⁸

By 1895, Marconi introduced to the public a device in London, asserting it was his invention. Despite Marconi's statements to the contrary, though, the apparatus resembles Tesla's descriptions in the widely translated articles.²⁹ Marconi's later practical four-tuned system was pre-dated by N. Tesla, Oliver Lodge, and J. S. Stone.³⁰ Marconi’s late-1895 transmission of signals was for around a mile.³¹

Marconi's reputation is largely based on these accomplishments in radio communications and commercializing a practical system. His demonstrations of the use of radio for wireless communications, equipping ships with life saving wireless communications, establishing the first transatlantic radio service, and building the first stations for the British short wave service, have marked his place in history.

Transatlantic transmissions

In 1901, Marconi claimed to have received daytime transatlantic radio frequency signals at a wavelength of 366 metres (820 kHz).³²³³³⁴ This Poldhu to Newfoundland transmission claim has been criticized.³⁵ Critics have claimed that it is more likely that Marconi received stray atmospheric noise from atmospheric electricity in this experiment.³⁶ The transmitting station in Poldhu, Cornwall used a spark-gap transmitter that could produce a signal just below the medium frequency and with high power levels.³⁷ The message received was the morse letter 'S' - three dots. Dr Jack Belrose has recently contested this, however, based on theoretical work as well as a reenactment of the experiment; he believes that Marconi heard only random atmospheric noise and mistook it for the signal. There are various science historians who agree with Jack Belrose that the Atlantic was not bridged in 1901,³⁸ but other science historians have taken the position that this was the first trans-atlantic radio transmission.

In 1902, Marconi transmitted from his station in Glace Bay, Nova Scotia, Canada, across the atlantic and on 18 January 1903 a Marconi station built near Wellfleet, Massachusetts in 1901 sent a message of greetings from Theodore Roosevelt, the President of the United States, to King Edward VII of the United Kingdom, marking the first transatlantic radio transmission originating in the United States.

20th century patents

Shortly after the turn of the 20th century, the US Patent Office re-awarded Marconi a patent for radio. The U.S. Patent RE11,913 was granted on June 4, 1901. Marconi's U.S. Patent 676,332 was awarded on June 11, 1901, also. This system was more advanced than his previous works.

Summary of "inventors of radio"

Name	Pro	Con	Earliest transmission
Bose	Researched coherers.³⁹⁴⁰ Transmitted microwaves over distance of 75 feet in 1895.⁴¹⁴² Had transmitted microwaves nearly a mile by 1896.⁴³⁴⁴⁴⁵	Did not pursue commercialization. ⁴⁶⁴⁷	1895
Deforest⁴⁸	Developed the triode amplifier and the Audion tube.	Late upon beginning research into space telegraphy.	1896⁴⁹⁵⁰
Henry	Henry detected electromagnetic effects at a distance of two hundred feet.⁵¹⁵²⁵³	He was focused on wired telegraphy and researched self-inductance.⁵⁴⁵⁵	1829⁵⁶
Hertz	By 1888, Hertz had studied and understood the work of Maxwell and, by design, produced the first clear and undisputed experimental evidence for the transmission and reception of radio waves.⁸	Hertz took this work no further, did not exploit it commercially, and famously did not consider it useful.⁸	1888
Hughes	In 1879, Hughes began research into radio waves. He noticed electrical interference in an induction balance he was working with.⁵⁷⁵⁸ The observed effect was due to radio waves and he discovered and improved the coherer.⁵⁹	Hughes was not trying to design equipment for wireless communication. His discovery was taken no further.⁵⁹	1879⁵⁹⁶⁰
Lodge	On 14 August 1894 Lodge sent a radio message in Morse code.⁶¹	Did not pursue further.⁶²	1894
Loomis	In 1872, received a patent for a "wireless telegraph". Patent utilizes atmospheric electricity to eliminate the overhead wire used by the existing telegraph systems.	His patent U.S. Patent 129,971 was for the purpose of receiving and imparting atmospheric electricity.	None (n/a)
Marconi	In summer 1895, Marconi sent signals 1.5 km.⁶³ In 1896, applied for British patent protection for a radio system. In 1900, he was granted British patent No. 12,039. Transmission over 6 km in March and May 1897.⁶⁴ Transatlantic transmission on 12 December 1901.⁶⁵ Tansmission over 3,378 km in February 1902.⁶⁶ Transatlantic message on 17 December 1902.⁶⁷ In 1897 Marconi founded "Wireless Telegraph and Signal Company"⁶⁸ and exploited the "Marconi System"⁶⁹⁷⁰⁷¹⁷² of radio commercially. He shared the 1909 Nobel Prize in Physics with Karl Ferdinand Braun, "in recognition of their contributions to the development of wireless telegraphy".⁷³	His 1901 transatlantic transmission is disputed.³⁵ Many of Marconi's system components were developed by others.⁷⁴ Oliver Lodge claimed British patent of 1900 to contain his own ideas which he failed to patent.	1895
Maxwell	By 1864 Maxwell had become the first person to demonstrate theoretically the existence of radio (electromagnetic) waves, which are used by all radio equipment.⁷⁵⁷⁶	Maxwell did not generate or receive radio waves.⁷⁷	None (n/a)
Popov	Confirmed laboratory demonstration of radio on 17 May 1895. In March 1896 publicly demonstrated the sending of a signal 550 m between two campus buildings.⁷⁸ By 1900 he had reliable communications over 25 miles.⁷⁹	Was not the first to send signals significant distances.⁸⁰	1895
Tesla	Tesla developed means to reliably produce radio frequency currents.⁸¹ In 1891 and afterwards, lectured about high-frequency devices and demonstrated devices using power without the use of wires.⁸²⁸³⁸⁴⁸⁵⁸⁶⁸⁷ Referring to a demonstration of his wireless equipment in 1893 the IEE said "the apparatus that he employed contained all the elements of spark and continuous wave that were incorporated into radio transmitters before the advent of the vacuum tube".⁸⁸ By 1895, stated that he had the ability to transmit signals under 50 miles.⁸⁹¹⁹⁹⁰⁹¹⁹² In 1897, Tesla applied for protection for the radio arts.⁹³ In 1900 Tesla was granted U.S. Patent 645,576 ⁹⁴ and U.S. Patent 649,621 ⁹⁵. In 1898, demonstrated a radio controlled boat in Madison Square Garden that allowed secure communication⁹⁶⁹⁷ between transmitter and receiver.⁹⁸ After 1915, assisted the Telefunken engineers in constructing the Telefunken Wireless Station (the "Arco-Slaby system"⁶⁹) in Sayville, Long Island.	No independently confirmed radio transmissions before 1898. Primarily because of financial difficulties, Tesla never completed his "worldwide wireless system".⁹⁹ The Wardenclyffe Tower transceiver that he began at Shoreham on Long Island, New York was eventually torn down.	1891 ¹⁰⁰¹⁰¹
Ward	Ward was the first person to be granted a US patent relating to wireless telegraphy.¹⁰²¹⁰³	His patent U.S. Patent 126,356 was for the purpose of receiving and imparting natural electricity.¹⁰⁴	None (n/a)

Tesla vs. Marconi

Radio patent decision

In 1943 a lawsuit regarding Marconi's US radio patents was resolved by the United States Supreme Court, who overturned most of these. The Marconi Company brought this suit in the Court of Claims to recover damages for infringement of four United States patents. Two, U.S. Patent 763,772 and U.S. Patent RE11,913 , were issued to Marconi, a third, U.S. Patent 609,154 , to Lodge, and a fourth, U.S. Patent 803,684 , to Fleming. The court held that the Marconi reissue patent was not infringed. In its consideration of radio communication systems, the United States courts accepted a "definition evolved out of the exhaustive depositions taken from many technical experts..."¹⁰⁵ as requiring "two tuned circuits each at the transmitter and receiver, all four tuned to the same frequency."¹⁰⁵¹⁰⁶¹⁰⁷

The court found Marconi showed no invention over Stone (U.S. Patent 714,756 ) by making the tuning of his antenna circuit adjustable, or by using Lodge's variable inductance for that purpose. The court decision was based on the proven prior work conducted by others, such as by Nikola Tesla, Oliver Lodge, and John Stone Stone, from which some of Marconi patents stemmed. At the time, the United States Army was involved in a patent infringement lawsuit with Marconi's company regarding radio, leading various observers to posit that the government nullified Marconi's other patents in order to moot any claims for compensation (as, it is speculated, the government's initial reversal to grant Marconi the patent right in order to nullify any claims Tesla had for compensation).

References

^ ^a ^b ^c The Invention of Radio inventors.about.com/od/rstartinventions/a/radio.htm
^ Such waves are usually systematically altered (by modulation) to carry signals.
^ Brother Potamian (1913). "Francesco Zantedeschi article at the Catholic Encyclopedia". Wikisource. Retrieved on 2007-06-16.
^ Baggott, Jim (2 September 1991). "The myth of Michael Faraday: Michael Faraday was not just one of Britain's greatest experimenters. A closer look at the man and his work reveals that he was also a clever theoretician". Retrieved on 2008-09-06.
^ Massie, W. W., & Underhill, C. R. (1911). Wireless telegraphy and telephony popularly explained. New York: D. Van Nostrand.
^ Hertzian Waves (1901) Accessed 2008-08-11
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^ ^a ^b ^c ^d Eugenii Katz, "Heinrich Rudolf Hertz". Biographies of Famous Electrochemists and Physicists Contributed to Understanding of Electricity, Biosensors & Bioelectronics.
^ "On Light and Other High Frequency Phenomena". Delivered before the Franklin Institute, Philadelphia, February 1893, and before the National Electric Light Association, St. Louis, March 1893.
^ "Experiments with Alternating Currents of High Potential and High Frequency". Delivered before the Institution of Electrical Engineers, London, February 1892.
^ ^a ^b "Nikola Tesla, 1856 - 1943". IEEE History Center, IEEE, 2003.
^ Martin, T. C., & Tesla, N. (1894). The inventions, researches and writings of Nikola Tesla, with special reference to his work in polyphase currents and high potential lighting. New York: The Electrical Engineer.
^ The True Wireless, Electrical Experimenter, May 1919, pages 28-30, 61-63, 87.
^ "Jagadish Chandra Bose". ieee-virtual-museum.org.
^ Bondyopadhyay, Probir K., "Sir J. C. Bose's Diode Detector Received Marconi's First Transatlantic Wireless Signal Of December 1901 (The "Italian Navy Coherer" Scandal Revisited)". Proc. IEEE, Vol. 86, No. 1, January 1988.
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^ Johnson, R., & Brown, J. H. (1904). "Nikola Tesla", The twentieth century biographical dictionary of notable Americans. Boston: Biographical Society. (cf., He was called the father of wireless telegraphy, which theory he first described in a lecture before the National Electric Light association at St. Louis, Mo., March, 1893; his ideas being given practical demonstration by Marconi in 1902.)
^ U.S. Patent 454,622 , June 23, 1891 (ed., This patent is cited in Maver's Wireless Telegraphy by William Maver on Page 165.)
^ ^a ^b Tesla, N., & Childress, D. H. (2000). The Tesla papers. Kempton, Ill: Adventures Unlimited. Page 136.
^ Nikola Tesla On His Work With Alternating Currents and Their Application to Wireless Telegraphy, Telephony and Transmission of Power : An Extended Interview. Chapter IV ISBN 1-893817-01-6 (cf., [Counsel] What do you mean by high frequencies?
[Tesla] I mean frequencies of 30,000, 40,000, 50,000, or something like that.
[Counsel] And by means of that machine, you put undamped waves of frequency about 50,000 into that antenna at Houston Street in 1895?
[Tesla] No [with that machine], not in 1895. Late in 1895 the machine was furnished and I began to operate in early 1896. That is when I began to operate.
[Counsel] Then you did this, that I speak of, in 1896?
[Tesla] Yes, from 1896 to 1899, right along.)
^ "Nikola Tesla On His Work with Alternating Currents and Their Application to wireless Telegraphy, Telephony, and Transmission of Power", Leland I. Anderson, Twenty First Century Books, 2002, pp. 26-27.]
^ PBS: Marconi and Tesla: Who invented radio?
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^ "ibid"
^ D.T. Emerson, "The work of Jagadis Chandra Bose: 100 years of mm-wave research". National Radio Astronomy Observatory, February 1998.
^ Gunston, D. (1965). Guglielmo Marconi, father of radio. London: Weidenfeld & Nicolson.
^ Henry M. Bradford, "Marconi's Three; Transatlantic Radio Stations In Cape Breton". Read before the Royal Nova Scotia Historical Society, 31 January 1996. (ed. the site is reproduced with permission from the Royal Nova Scotia Historical Society Journal, Volume 1, 1998.)
^ Marconi's Three; Transatlantic Radio Stations In Cape Breton.
^ P.J.Papadopoulos, "Nikola Tesla; The Guglielmo Marconi Case, Who is the True Inventor of Radio?" Originally at http://www.mercury.gr/tesla/marcen.html
^ Tesla was the first, though, to expound the principles of the four-tuned system. The earlier two-tuned systems were not practical for commercial activity (as found in the United States court case). In addition, other prior work was conducted by others (such as by Hertz and Braun, but not excluding others) from which many of Marconi's devices and methods were derived. Marconi's U.S. Patent 676,332 Apparatus for wireless telegraphy [1901], in which a more intricate system was disclosed than in his earlier patents, was filed after contributions made by other investigators.
^ This was small when put against Tesla's transmissions below 50 miles.
^ Henry M. Bradford, "Marconi in Newfoundland: The 1901 Transatlantic Radio Experiment".
^ Henry M. Bradford, "Did Marconi Receive Transatlantic Radio Signals in 1901? - Part 1". Wolfville, N.S..
^ Henry M. Bradford, "Did Marconi Receive Transatlantic Radio Signals in 1901? Part 2, Conclusion: The Trans-Atlantic Experiments". Wolfville, N.S..
^ ^a ^b John S. Belrose, "Fessenden and Marconi; Their Differing Technologies and Transatlantic Experiments During the First Decade of this Century" International Conference on 100 Years of Radio, 5-7 September, 1995. Accessed 2008-08-09
^ "Marconi's Error: The First Transatlantic Wireless Telegraphy in 1901"
^ A maximum time-averaged power of 35 kilowatts, but with a peak pulse power of megawatts.
^ In addition to being bolstered by Tesla supporters.
^ Fleming, J. A. (1908). The principles of electric wave telegraphy. London: New York and. (cf., [...] researches of Professor J. C. Bose are of particular interest. He states that the sensitiveness of any form of contact cymoscope consisting of conducting particles depends upon the proper adjustment of the pressure between the particles and the value of the external electromotive force which is in waiting, so to speak, to send or increase the current through the contacts.) See J. C. Bose, Proc. Soy. Soc. Land., 1899, vol. G5, p. 166 ; or Science Abstracts, vol. ii. No. 1716.
^ Institution of Electrical Engineers, Physical Society (Great Britain), American Physical Society, American Institute of Electrical Engineers, Electrochemical Society, & Associazione elettrotecnica italiana. (1898). Science abstracts. [London]: Institution of Electrical Engineers. Page 963
^ Prof Rajesh Kochhar, J.C. BOSE: The Inventor Who Wouldn’t Patent. Science Reporter, Feb 2000
^ The life and work of Sir Jagadis C. Bose on page 62
^ In 1896, the Daily Chronicle of England reported on his UHF experiments: "The inventor (J.C. Bose) has transmitted signals to a distance of nearly a mile and herein lies the first and obvious and exceedingly valuable application of this new theoretical marvel."
^ Jagadis Chandra Bose and His Pioneering Research on Microwave
^ jcbose, calcuttaweb.com
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^ Geddes, P. (1920). The life and work of Sir Jagadis C. Bose. London: Longmans, Green.
^ De Forest, L. (1950). Father of radio: the autobiography of Lee de Forest. Chicago: Wilcox & Follett.
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^ Fritz E. Froehlich, Allen Kent, (1992). The Froehlich/Kent Encyclopedia of Telecommunications: Volume 4 - Communications Human Factors to Cryptology. CRC Press. Page 285. ISBN 082472903X
^ Fleming, J. A. (1908). The principles of electric wave telegraphy. London: New York and Co. (cf., Joseph Henry, in the United States, between 1842 and 1850, explored many of the puzzling facts connected with this subject, and only obtained a clue to the anomalies when he realized that the discharge of a condenser through a low resistance circuit is oscillatory in nature. Amongst other things, Henry noticed the power of condenser discharges to induce secondary currents which could magnetize steel needles even when a great distance separated the primary and secondary circuits.)
^ See "The Scientific Writings" of Joseph Henry, vol. i. pp. 203, 20:-i ; also Proceedings of tltc American Assoc. fur Advancement of Science, 1850, vol. iv. pp. 877, 378, Joseph Henry, "On the Phenomena of the Leyden Jar." The effect of the oscillatory discharge on a magnetized needle is clearly described in this paper.
^ Ames, J. S., Henry, J., & Faraday, M. (1900). The discovery of induced electric currents. New York: American book. (cf. On moving to Princeton, in 1832, [...] investigated also the discharge of a Leyden jar, proved that it was oscillatory in character, and showed that its inductive effects could be detected at a distance of two hundred feet, thus clearly establishing the existence of electro-magnetic waves.)
^ Eugenii Katz, "Joseph Henry". Biographies of Famous Electrochemists and Physicists Contributed to Understanding of Electricity, Biosensors & Bioelectronics.
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^ http://tenwatts.blogspot.com/2006/03/bio-david-e-hughes.html
^ ^a ^b ^c Darrel T. Emerson, The Stage Is Set: Developments before 1900 Leading to Practical Wireless Communication
^ Eugenii Katz, "David Edward Hughes". Biographies of Famous Electrochemists and Physicists Contributed to Understanding of Electricity, Biosensors & Bioelectronics.
^ Peter Rowlands (ed.) and J. Patrick Wilson (ed.) "Oliver Lodge and the Invention of Radio" ISBN 1-873694-02-4
^ OTB - Oliver Lodge: Almost the Father of Radio. antiquewireless.org.
^ Guglielmo Marconi -- Britannica Online Encyclopedia
^ BBC Wales, "Marconi's Waves"
^ Marconi's Achievement (1902)
^ http://www.ieee.ca/millennium/radio/radio_differences.html
^ Marconi's Wellfleet (Cape Cod) Wireless. Stormfax.
^ "Wireless Telegraph and Signal Company" was formed on 20 July 1897 after granting of a British patent
^ ^a ^b Collins, A. F. (1913). Manual of wireless telegraphy and telephony. New York: J. Wiley. Page 177 - 209
^ http://home.luna.nl/~arjan-muil/radio/marconi/marconi-system.html
^ Beauchamp, K. G. (2001). History of telegraphy. London: Institution of Electrical Engineers. Page 206
^ American Institute of Electrical Engineers. (1884). Transactions of the American Institute of Electrical Engineers. New York: American Institute of Electrical Engineers. Page 120
^ "Guglielmo Marconi: The Nobel Prize in Physics 1909"
^ "Marconi Wireless Tel. Co. v. United States, 320 U.S. 1 (U.S. 1943)", 320 U.S. 1, 63 S. Ct. 1393, 87 L. Ed. 1731 Argued April 9,12, 1943. Decided June 21, 1943. http://caselaw.lp.findlaw.com/scripts/printer_friendly.pl?page=us/320/1.html (cf., But it is now held that in the important advance upon his basic patent Marconi did nothing that had not already been seen and disclosed.)
^ "Electromagnetism, Maxwell’s Equations, and Microwaves". IEEE Virtual Museum (2008). Retrieved on 2008-06-02.
^ James Clerk Maxwell, A Dynamical Theory of the Electromagnetic Field, Philosophical Transactions of the Royal Society of London 155, 459-512 (1865).
^ Estabrooks, M. (1995). Electronic technology, corporate strategy, and world transformation. Westport, Conn: Quorum Books. Page 27. (cf., [...] Maxwell did not prove that these waves actually existed [...])
^ "Early Radio Transmission Recognized as Milestone". IEEE. Retrieved on July 16, 2006.
^ Eugenii Katz, "Alexander Stepanovich Popov ". Biographies of Famous Electrochemists and Physicists Contributed to Understanding of Electricity, Biosensors & Bioelectronics.
^ By 1895, Tesla stated that he had the ability to transmit signals under 50 miles
^ U.S. Patent 447,920
^ Tesla's presentation at the Franklin Institute was reported across America (such as in The Century Magazine) and throughout Europe.
^ "Nikola Tesla, 1856 - 1943". IEEE History Center, IEEE, 2003. (cf., In 1891 he lectured on his high-frequency devices to the American Institute of Electrical Engineers, and this lecture, coupled with a spectacular demonstration of these apparatuses, made him famous. He [later in 1892] repeated his performance in Europe, to great acclaim, and enjoyed international celebrity.)
^ "On Light and Other High Frequency Phenomena". Delivered before the Franklin Institute, Philadelphia, February 1893, and before the National Electric Light Association, St. Louis, March 1893.
^ "Experiments with Alternating Currents of High Potential and High Frequency". Delivered before the Institution of Electrical Engineers, London, February 1892.
^ Tesla; Man Out of Time By Margaret Cheney. Page 144.
^ Ljubo Vujovi, "Tesla Biography; Nikola Tesla, The genius who lit the world". Teslasociety.com.
^ "Nikola Tesla, 1856 - 1943". IEEE History Center, IEEE, 2003. (cf., In a lecture-demonstration given in St. Louis in [1893] - two years before Marconi's first experiments - Tesla also predicted wireless communication; the apparatus that he employed contained all the elements of spark and continuous wave that were incorporated into radio transmitters before the advent of the vacuum tube.)
^ Nikola Tesla On His Work With Alternating Currents and Their Application to Wireless Telegraphy, Telephony and Transmission of Power : An Extended Interview. Chapter IV ISBN 1-893817-01-6 (cf., [Counsel] What form of device did you use, and where did you use it, for noting the generation of these oscillations or waves in the antenna?
[Tesla] [...] With such an instrument, I operated, for instance, in West Point — I received signals from my laboratory on Houston Street in West Point.
[Counsel] This was then the machine that you used when working with West Point?
[Tesla] I operated once or twice with it at that distance, but usually as I was investigating in the city. [...]")
^ Who Invented Radio? (cf., By early 1895, Tesla was ready to transmit a signal 50 miles to West Point, New York ... But in that same year, disaster struck. A building fire consumed Tesla's lab, destroying his work.)
^ Leland I. Anderson (ed.), "John Stone Stone, Nikola Tesla's Priority in Radio and Continuous-Wave Radiofrequency Apparatus". The Antique Wireless Review, Vol. 1. 1986. 24 pages, illustrated. (ed., available at Twenty First Century Books)
^ Marshall Cavendish Corporation. (2008). Inventors and inventions. New York: Marshall Cavendish. Page 1395
^ U.S. Supreme Court, "Marconi Wireless Telegraph co. of America v. United States". 320 U.S. 1. Nos. 369, 373. Argued April 9-12, 1943. Decided June 21, 1943. (cf. The Tesla patent No. 645,576, applied for September 2, 1897, [...] disclosed a four-circuit system, having two circuits each at transmitter and receiver, and recommended that all four circuits be tuned to the same frequency. [... the apparatus could be] used for wireless communication, which is dependent upon the transmission of electrical energy.)
^ "System of Transmission of Electrical Energy", (March 20, 1900; filed Sept. 2, 1897)
^ "Apparatus for Transmission of Electrical Energy" (May 15, 1900; filed February 19, 1900)
^ Tesla, N., & Anderson, L. I. (1998). Nikola Tesla: guided weapons & computer technology. Tesla presents series, pt. 3. Breckenridge, Colo: Twenty First Century Books.
^ Tesla, N., & Anderson, L. I. (2002). Nikola Tesla on his work with alternating currents and their application to wireless telegraphy, telephony, and transmission of power: an extended interview. Tesla presents series, pt. 1. Breckenridge, Colo: Twenty-First Century Books.
^ The schematics are illustrated in U.S. Patent 613,809 and describes "rotating coherers".
^ Wardenclyffe - A Forfeited Dream
^ Tesla, Nikola (1891). "Experiments with Alternate Currents of Very High Frequency and Their Application to Methods of Artificial Illumination".
^ The True Wireless. Electrical Experimenter, May 1919, pages 28-30, 61-63, 87. (cf., The popular impression is that my wireless work was begun in 1893, but as a matter of fact I spent the two preceding years in investigations, employing forms of apparatus, some of which were almost like those of today.)
^ earlyradiohistory Fakes, Frauds, and Cranks (1866-1922)
^ The patent called for construction so as to collect, hold, distribute, and utilize aerial currents of natural electricity for telegraphic and other purposes.
^ Specification forming part of Letters Patent No. 126,356, dated April 30, 1872.
^ ^a ^b Margaret Cheney (2001). Tesla: Man Out of Time. Simon and Schuster. ISBN 0743215362.
^ 320 U.S. 1. Marconi Wireless Telegraph co. of America v. United States
^ Cheney, M., Uth, R., & Glenn, J. (1999). Tesla, Master of Lightning. New York: Barnes & Noble Books. Page 71.
^ U.S. Supreme Court, "Marconi Wireless Telegraph co. of America v. United States". 320 U.S. 1. Nos. 369, 373. Argued April 9-12, 1943. Decided June 21, 1943.
^ ^a ^b Wireless Telegraph co. of America v. United States.

Contents

Physics of radio

Early theories and experiments

Complete theory of electromagnetism

Innovations and laboratory experiments

Hughes

Hertz

Tesla

Bose

Edison

Early Commercial exploitation

Tesla

Radio frequency generation

Continued research and patents

Popov

Marconi

Early years

Transatlantic transmissions

20th century patents

Summary of "inventors of radio"

Tesla vs. Marconi

Radio patent decision

References

Additional reading

See also