Invention of radio
Many people were involved in the invention of radio as we now know it. Several possible methods of wireless communication were considered, including inductive and capacitive induction and transmission through the ground, however the method used for radio today exclusively involves the transmission and reception of electromagnetic waves.
After early speculation on the subject, experimental work on the connection between electricity and magnetism began around 1820 with the work of Hans Christian Ørsted and continued with the work of André-Marie Ampère, Joseph Henry, and Michael Faraday. These investigations culminated in the complete theory of electromagnetism developed by James Clerk Maxwell. This theory described the theoretical basis of the propagation of electromagnetic waves.
After Maxwell's theory was published many people experimented with wireless communication, some intentionally using Maxwell's theory some not. It is considered likely that the first intentional transmission of a signal by means of electromagnetic waves was performed by David Edward Hughes around 1880, although this was considered to be induction at the time. The first systematic and unequivocal transmission of EM waves was performed by Heinrich Rudolf Hertz and described in papers published in 1887 and 1890. Hertz famously considered these results as being of little practical value.
After Hertz's work many people were involved in the development of components and theory involved with the transmission and reception of electromagnetic waves. Others, notably Guglielmo Marconi, were concerned with practical improvements and the commercial application of radio to wireless telegraphy. Later on Reginald A. Fessenden became the first to send an audio signal by means of electromagnetic waves.
Wireless signalling methods
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:
- Electrical conduction through the ground, or through water.
- Magnetic induction
- Capacitive coupling
- Electromagnetic waves
All these physical phenomena, as well as various other ideas such as conduction through air, were tested for the purpose 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 today for long-distance wireless communications involves the use of modulated electromagnetic waves, which is radio.
Radio antennas radiate electromagnetic waves that can reach the receiver either directly by line of sight, by ground wave propagation, by refraction from the ionosphere, known as sky wave propagation, and occasionally by refraction in lower layers of the atmosphere (tropospheric ducting).
Theory of electromagnetism
Various scientists proposed that electricity and magnetism were linked. In 1802 Gian Domenico Romagnosi suggested the relationship between electric current and magnetism but his reports went unnoticed. In 1820 Hans Christian Ørsted performed a simple and today widely known experiment on man-made electric current and magnetism. He demonstrated that a wire carrying a current could deflect a magnetized compass needle. Ørsted's work influenced André-Marie Ampère to produce a theory of electromagnetism.
In 1832 Joseph Henry performed experiments detecting inductive magnetic effects over a distance of 200 feet (61 m). He was the first (1838–42) to produce high frequency AC electrical oscillations, and to point out and experimentally demonstrate that the discharge of a condenser under certain conditions is oscillatory, or, as he puts it, consists "of a principal discharge in one direction and then several reflex actions backward and forward, each more feeble than the preceding until equilibrium is attained". This view was also later adopted by Helmholz, but the mathematical demonstration of this fact was first given by Lord Kelvin in his paper on "Transient Electric Currents".
In 1831, Michael Faraday began a series of experiments in which he discovered electromagnetic induction. The relation was mathematically modelled by Faraday's law, which subsequently became one of the four Maxwell equations. Faraday proposed that electromagnetic forces extended into the empty space around the conductor, but did not complete his work involving that proposal. In 1846 Michael Faraday speculated that light was a wave disturbance in a force field".
Electromagnetic waves and Maxwell's equations
Between 1861 and 1865, based on the earlier experimental work of Faraday and other scientists, James Clerk Maxwell developed his theory of electromagnetism, which predicted the existence of electromagnetic waves. In 1873 Maxwell described the theoretical basis of the propagation of electromagnetic waves in his paper to the Royal Society, "A Dynamical Theory of the Electromagnetic Field." This theory united all previously unrelated observations, experiments and equations of electricity, magnetism, and optics into a consistent theory. His set of equations—Maxwell's equations—demonstrated that electricity, magnetism, and light are all manifestations of the same phenomenon, the electromagnetic field. Subsequently, all other classic laws or equations of these disciplines were special cases of Maxwell's equations. Maxwell's work in electromagnetism has been called the "second great unification in physics".
Although Maxwell did not transmit or receive radio waves his equations still remain the basis of all radio design.
Development of wireless telegraphy
In the late 19th century it was clear that wireless communication was possible. Theoretical and experimental innovations during this time period led to the development of radio communication systems as they exist today. Some early work was done by local effects and experiments of electromagnetic induction. It was learned that "ethereal telegraphy" and telegraphy by induction were distinct phenomena.
Early attempts at wireless communication
In April 1872 William Henry Ward received U.S. Patent 126,356 for radio development. However, this system did refer to convection current transmission and never received and transmitted radio waves in the marketplace.
A few months after Ward received his patent, Mahlon Loomis of West Virginia received U.S. Patent 129,971 for a "wireless telegraph" in July 1872. This claimed to utilize atmospheric electricity to eliminate the overhead wire used by the existing telegraph systems. It did not contain diagrams or specific methods and it did not refer to or incorporate any known scientific theory. It is substantially similar to William Henry Ward's patent and did not become a market radio machine.
Towards the end of 1875, while experimenting with the telegraph, Thomas Edison noted a phenomenon that he termed "etheric force", announcing it to the press on November 28. He abandoned this research when Elihu Thomson, among others, ridiculed the idea. The idea was not based on the electromagnetic waves described by Maxwell. In 1885, Edison took out U.S. Patent 465,971 on a system of electrical wireless communication between ships (which later he sold to the Marconi Company). The patent, however, was based on the mutual-inductively coupled or magnetically coupled communication.
Wireless telephony is documented from four patents for the photophone, invented jointly by Alexander Graham Bell and Charles Sumner Tainter in 1880. The photophone allowed for the transmission of sound on a beam of light, and on June 3, 1880 Bell and Tainter transmitted the world's first wireless telephone message on their newly invented form of telecommunication.
Roberto Landell de Moura, a Brazilian priest and scientist, went to Rome in 1878 and studied at the South American College and Pontifical Gregorian University, where he studied physics and chemistry. He completed his clerical training in Rome, graduating in theology, and was ordained a priest in 1886. In Rome, he began studying physics and electricity. When he returned to Brazil, he conducted experiments in wireless in Campinas and São Paulo (1892–1893). According to the newspaper Jornal do Comercio (June 10, 1900), he conducted his first public experiment on June 3, 1900, in front of journalists and the General Consul of Great Britain, Mr. C.P. Lupton, in the City of São Paulo, Brazil, reaching a distance of approximately 8 km. The points of transmission and reception were the Alto de Santana and Paulista Avenue in the downtown sector. One year after the above experiment in public, he received his first patent from the Brazilian government. It was described as "equipment for the purpose of phonetic transmissions through space, land and water elements at a distance with or without the use of wires". Upon observing the experiments, Rodriguez Botet, giving news of the trials, said he was not far from the moment of the consecration of Landell as an author of radio discoveries. Wireless telephony is reputed the most important discovery of Landell. De Moura did later pursue and receive several patents on wireless technology. Four months later, conscious that his invention had real value, he left Brazil for the United States of America with the intent of patenting the machine at the U S Patent Office in Washington, DC. With scarce resources he had to rely on friends to push ahead his project. In spite of great difficulties, three patents were finally awarded: "The Wave Transmitter" (October 11, 1904) which is the precursor of today's radio transceiver; "The Wireless Telephone" and the "Wireless Telegraph", both dated November 22, 1904.
Premininary experiments and proposals
Berend Wilhelm Feddersen (German physicist) in 1859, as a private scholar in Leipzig, succeeded in experiments with the Leyden jar to prove that electric sparks were composed of discharge (damped) oscillations. He realized that they arise from a coil, capacitor and resistor existing electrical circuit oscillations.
In 1870 the German physicist Wilhelm von Bezold discovered and demonstrated the fact that the advancing and reflected oscillations produced in conductors by a condenser discharge gave rise to interference phenomena. Professors Elihu Thomson and E. J. Houston in 1876 made a number of experiments and observations on high frequency oscillatory discharges. In 1883 G. F. Fitzgerald suggested at a British Association meeting that electromagnetic waves could be generated by the discharge of a condenser, but the suggestion was not followed up, possibly because no means was known for detecting the waves.
Early development of wireless telegraphy
In 1879, David Edward Hughes discovered that sparks would generate a signal, now believed to be radio, that could be detected by listening to a telephone receiver connected to his new microphone design. He developed his spark-gap transmitter and receiver into a working communication system using trial and error experiments, until eventually he could demonstrate the ability to send and receive Morse code signals out to a range limited to 500 yards (460 m). Prominent attendees of the demonstrations were Sir William Crookes Sir William Henry Preece, William Grylls Adams, and James Dewar.
Hughes demonstrated his technology to representatives of the Royal Society in February 1880, but it was incorrectly dismissed as merely induction. Hughes' work was not published until a brief mention of it in 1892, and a full magazine article was written about it in 1899.
Hughes discovered that his microphone design exhibited unusual properties in the presence of radio signals. He experimented with the discovery, and described his creation of both the device later known as a "coherer", and an improved semiconductor carbon and steel point-contact rectifying diode, which he also called a "coherer". The point-contact diode version of the device is now known as a crystal radio detector, and was the key component of his sensitive crystal radio receiver[dubious ].
Elihu Thomson recognized the Hughes claim to be the first to transmit radio. Hughes himself said "with characteristic modesty" that Hertz's experiments were "far more conclusive than mine", and that Marconi's "efforts at demonstration merit the success he has received...[and] the world will be right in placing his name on the highest pinnacle, in relation to aerial electric telegraphy".
Between 1886 and 1888 Heinrich Rudolf Hertz studied Maxwell's theory and conducted experiments that validated it through more rigorous scientific techniques than Hughes had used. He engineered a method of detecting spark-gap radio waves by observing that another unpowered spark-gap, acting as an antenna, would absorb the radio energy and convert it back into an electric spark. Hertz published his results in a series of papers between 1887 and 1890, and again in complete book form in 1893.
The first of the papers published, "On Very Rapid Electric Oscillations", gives an account of the chronological course of his investigation, as far as it was carried out up to the end of the year 1886 and the beginning of 1887.
For the first time, electromagnetic radio waves ("Hertzian waves") were intentionally and unequivocally proven to have been transmitted through free space by a spark-gap device, and detected over a short distance.
Hertz was able to have some control over the frequencies of his radiated waves by altering the inductance and capacitance of his transmitting and receiving antennas. He focused the electromagnetic waves using a corner reflector and a parabolic reflector, to demonstrate that radio behaved the same as light, as Maxwell's electromagnetic theory had predicted more than 20 years earlier. He demonstrated that radio had all the properties of waves, and discovered that the electromagnetic equations could be reformulated into a partial differential equation called the wave equation.
Hertz did not devise a system for practical utilization of radio, nor did he describe any potential applications of the technology. He seemed uninterested in the useful importance of his experiments. When asked what the ramifications were for his work, Hertz replied, "Nothing, I guess." He also said, "I do not think that the wireless waves...will have any practical application."
Hertz died in 1894, and the art of radio was left to others to implement into a practical form. After Hertz's experiments, Sir William Crookes published his thoughts on wireless technology for a wider audience, and Professor Amos Emerson Dolbear brought similar attention. The race toward a functioning, potentially profitable radio communication system had begun.
In 1890, Édouard Branly demonstrated what he later called the "radio-conductor," which Lodge in 1893 named the coherer, the first sensitive device for detecting radio waves. Shortly after the experiments of Hertz, Dr. Branly discovered that loose metal filings, which in a normal state have a high electrical resistance, lose this resistance in the presence of electric oscillations and become practically conductors of electricity. This Branly showed by placing metal filings in a glass box or tube, and making them part of an ordinary electric circuit. According to the common explanation, when electric waves are set up in the neighborhood of this circuit, electromotive forces are generated in it which appear to bring the filings more closely together, that is, to cohere, and thus their electrical resistance decreases, from which cause this piece of apparatus was termed by Sir Oliver Lodge a coherer. Hence the receiving instrument, which may be a telegraph relay, that normally would not indicate any sign of current from the small battery, can be operated when electric oscillations are set up. Prof. Branly further found that when the filings had once cohered they retained their low resistance until shaken apart, for instance, by tapping on the tube. The coherer, however, was not sensitive enough to be used reliably as radio developed.
In 1891 Nikola Tesla began his research into radio. Around July 1891 he developed various alternator apparatus that produced 15,000 cycles per second. In 1892 he delivered a lecture called "Experiments with Alternate Currents of High Potential and High Frequency" before the Institution of Electrical Engineers of London, in which he suggested that messages could be transmitted without wires. He repeated this presentation at the Royal Institution and at the Société Française de Physique in Paris.
In 1893, at St. Louis, Missouri, Tesla gave a public demonstration called, "On Light and Other High Frequency Phenomena",. 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.
In 1894, T. C. Martin published "The Inventions, Researches and Writings of Nikola Tesla", detailing the work of Tesla in the previous years. Various scientists, inventors, and experimenters began to investigate wireless methods. Tesla's work contained coupled oscillation circuits having capacity and inductance in series. In 1897, Tesla applied for two key United States radio patents, US 645576 , first radio system patent, and (later subdivided into) US 649621 , for protection of his interests of the radio arts. Tesla also developed sensitive electromagnetic receivers, that were unlike the less responsive coherers later used by other early experimenters.
Shortly thereafter, he began to develop wireless remote control devices. In 1898, he demonstrated a radio controlled boat in Madison Square Garden that allowed secure communication between transmitter and receiver. Between 1895 and 1897, Tesla received wireless signals transmitted via short distances in his lectures. Between 1897 and the first decade of the 1900s, he transmitted over medium ranges. Tesla had predicted that not only would intelligible signals be transmitted over long distances without wires, but electric power as well. He later published articles, such as "The True Wireless", and "The Transmission of Electric Energy Without Wires", concerning the World Wireless System research.
One of the first investigators to notice and measure stationary waves on wires produced by direct coupling (resonance) with the coatings of a Leyden jar was Sir Oliver Lodge, entitled "Experiments On The Discharge Of Leyden Jars" (1891). On June 1, 1894, Oliver Lodge at the Royal Institution lectures, delivered "The Work of Hertz and Some of His Successors". Two years after Tesla's high potential and high frequency lecture and five years after Hertz's signals, Lodge performed transmission on August 14, 1894. This was a year before Marconi's initial experiments. Lodge did this at a meeting of the British Association for the Advancement of Science at Oxford University. Also in 1894, Lodge would state that Alexander Muirhead clearly foresaw the telegraphic importance of the transmission of transverse Hertzian waves. A convenient method of establishing stationary electric waves on wires is one which generally attribute to Ernst Lecher, and call the Lecher arrangement. As a matter of fact, it originated with Lodge and Hertz, whilst Edouard Sarasin and Lucien de la Rive gave it an improved form.
On that day in August 1894, Lodge demonstrated the reception of Morse code signalling via radio waves using a "coherer". He later improved Branly's coherer by adding a "trembler" which dislodged clumped filings, thus restoring the device's sensitivity. In August 1898 he got U.S. Patent 609,154, "Electric Telegraphy", that made wireless signals using Ruhmkorff coils or Tesla coils for the transmitter and a Branly coherer for the detector. This patent was utilizing the concept of "syntonic" tuning. In 1912 Lodge sold the patent to Marconi.
|Lodge 1894 lecture|
In this lecture, Lodge stated that in his estimate the apparatus used would respond to signals at a distance of .5 miles (0.80 km).
In 1894 Lodge showed that the Branly coherer could be employed to transmit telegraphic signals, and in order that the filings should not remain "cohered" after the cessation of the electric oscillations, he devised an electro-mechanical "tapper" on the principle of the ordinary "buzzer," or electric door-bell, the hammer of which was caused to tap the glass tube as long as the electric oscillations continued. The filings thus virtually take the place of a key in the ordinary telegraph circuit. In the normal state the key is open; in the presence of electrical oscillations the key is closed. Thus, by opening and closing the key for a longer or shorter period, signals corresponding to dots and dashes may be produced. In other words, by setting up electric oscillations for periods of time corresponding to dots and dashes, messages may be transmitted from the sending station, and if, at the receiving station, a recording instrument (controlled by the coherer), such as the ordinary Morse register, be provided, a record of the message in dots and dashes may be obtained. Dr. Lodge in fact used a tapper operated continuously by clockwork.
In 1894, with the help of the Branly filings tube, Lodge gave a couple of demonstrations, one in June at the Royal Institution at Oxford and one in August at Oxford, to the British Association, using Hertz oscillators for transmitting signals, using a Morse key in connection with the sending coil, and a Thomson marine galvanometer for receiving them—sending the signals from one room to another through walls, and so on. Lodge sent them also across the quadrangle of Liverpool College, but he applied very small power and did not try for big distances. At that time Dr. Alexander Muirhead was struck with its applicability to practical telegraphy, and when in 1896 Sir William Preece told the British Association meeting (as it happened in his laboratory) at Liverpool that an Italian gentleman (at that time unknown) was interesting the Post Office in a secret box, Lodge knew practically what the box must contain, and immediately afterwards (the same day) he showed to a few friends a Morse tape instrument, very roughly working on that plan. Mr. Marconi and Sir William Preece together interested the whole world in the subject; great power was applied to the sender, and the matter became of financial importance. However, the American Patent Office gave Lodge a telegraphic patent based on his work, as published in 1894, after proof that this book had reached America in or before 1895.
In November 1894, the Indian physicist, Jagadish Chandra Bose, demonstrated publicly the use of radio waves in Calcutta, but he was not interested in patenting his work. Bose ignited gunpowder and rang a bell at a distance using electromagnetic waves, proving that communication signals can be sent without using wires. He sent and received radio waves over distance but did not commercially exploit this achievement.
The 1895 public demonstration by Bose in Calcutta was before Marconi's wireless signalling experiment on Salisbury Plain in England in May 1897. Bose demonstrated the ability of the electric rays to travel from the lecture room, and through an intervening room and passage, to a third room 75 feet (23 m) distant from the radiator, thus passing through three solid walls on the way, as well as the body of the chairman (who happened to be the Lieutenant-Governor). The receiver at this distance still had energy enough to make a contact which set a bell ringing, discharged a pistol, and exploded a miniature mine. To get this result from his small radiator, Bose set up an apparatus which curiously anticipated the lofty 'antennae' of modern wireless telegraphy— a circular metal plate at the top of a pole, 20 feet (6.1 m) high, being put in connection with the radiator and a similar one with the receiving apparatus.
The form of 'Coherer' devised by Professor Bose, and described by him at the end of his paper 'On a new Electro Polariscope' allowed for the sensibility and range to appear to leave little to be desired at the time. 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."
After Bose's Friday Evening Discourses at the Royal Institution, The Electric Engineer expressed 'surprise that no secret was at any time made as to its construction, so that it has been open to all the world to adopt it for practical and possibly money-making purposes.' Bose was sometimes, and not unnaturally, criticised as unpractical for making no profit from his inventions.
In 1899, Bose announced the development of an "iron-mercury-iron coherer with telephone detector" in a paper presented at the Royal Society, London. Later he received U.S. Patent 755,840, "Detector for electrical disturbances" (1904), for a specific electromagnetic receiver. Bose would continue research and made other contributuions to the development of radio.
Ferdinand Braun's major contributions were the introduction of a closed tuned circuit in the generating part of the transmitter, and its separation from the radiating part (the antenna) by means of inductive coupling, and later on the usage of crystals for receiving purposes. Braun experimented at first at the University of Strasbourg. Braun had written extensively on wireless subjects and was well known through his many contributions to the Electrician and other scientific journals. In 1899, he would apply for the patents, Electro telegraphy by means of condensers and induction colls and Wireless electro transmission of signals over surfaces.
Pioneers working on wireless devices eventually came to a limit of distance they could cover. Connecting the antenna directly to the spark gap produced only a heavily damped pulse train. There were only a few cycles before oscillations ceased. Braun's circuit afforded a much longer sustained oscillation because the energy encountered less loss swinging between coil and Leyden Jars. Also, by means of inductive antenna coupling the radiator was matched to the generator.
In spring 1899 Braun, accompanied by his colleagues Cantor and Zenneck, went to Cuxhaven to continue their experiments at the North Sea. On February 6, 1899, he would apply for the United States Patent, Wireless Electric Transmission of Signals Over Surfaces. Not before long he bridged a distance of 42 km to the city of Mutzing. On 24 September 1900 radio telegraphy signals were exchanged regularly with the island of Heligoland over a distance of 62 km. Lightvessels in the river Elbe and a coast station at Cuxhaven commenced a regular radio telegraph service. On August 6, 1901, he would apply for Means for Tuning and Adjusting Electric Circuits.
By 1904, the closed circuit system of wireless telegraphy, connected with the name of Braun, was well known and generally adopted in principle. The results of Braun's experiments, published in the Electrician, possess interest, apart from the method employed. Braun showed how the problem could be satisfactorily and economically solved. The closed circuit oscillator has the advantage, as was known, of being able to draw upon the kinetic energy in the oscillator circuit, and thus, because such a circuit can be given a much greater capacity than can be obtained with a radiating aerial alone, much more energy can be stored up and radiated by its employment. The emission is also prolonged, both results tending towards the attainment of the much desired train of undamped waves. The energy available, though greater than with the open system, was still inconsiderable unless very high potentials, with the attendant drawbacks, were used. Braun avoided the use of extremely high potentials for charging the gap and also makes use of a less wasteful gap by sub-dividing it. The chief point in his new arrangement, however, is not the sub-division of the gap merely but their arrangement, by which they are charged in parallel, at low voltages, and discharge in series. The Nobel Prize awarded to Braun in 1909 depicts this design.
Later radio development
During the Chicago World's Columbian Exhibition and the Third International Electrical Congress, Alexander Stepanovich Popov of Kronstadt, Russia was a representative of the Russian Torpedo School. Afterward, he worked on his wireless designs. Popov conducted experiments along the lines of Hertz's research. In 1894-95 he built his first radio receiver, an improved version of coherer-based design by Oliver Lodge. In 1895, he built a coherer. Popov constructed a filings coherer, one form of which was used in some surveying experiments by the Russian government. He used early in 1895, the coherer auto-tapping mechanism, and substituted for the galvanometer an ordinary telegraphic relay. He operated this apparatus at a distance by means of a large radiator. One terminal of his coherer was connected to a conductor fastened to a mast about 30 ft. high on the top of the Institute building and the other terminal of the coherer was grounded.
Popov presented his radio receiver to the Russian Physical and Chemical Society on May 7, 1895 — the day has been celebrated in the Russian Federation as "Radio Day". On this day, Popov performed a public demonstration of transmission and reception of radio waves used for communication at the Russian Physical and Chemical Society, using his coherer. 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. He did not apply for a patent for this invention. Popov's early experiments were transmissions of only 600 yards (550 m). Popov was the first to develop a practical communication system based on the coherer, and is usually considered by the Russians to have been the inventor of radio.
In 1895-96 Popov and others utilized the coherer to show the existence of atmospheric electricity, using for the purpose a vertical wire attached to the coherer. On March 24, 1896, Popov demonstrated in public the transmission of radio waves, between different campus buildings, to the Saint Petersburg Physical Society. (This was before the public demonstration of the Marconi system around September 1896.) Per other accounts, however, Popov achieved these results only in December 1897—that is, after publication of Marconi's patent. In 1898 his signal was received 6 miles (9.7 km) away, and in 1899 130 miles (210 km) away.
His receiver proved to be able to sense lightning strikes at distances of up to 30 km, thus functioning as a lightning detector. In late 1895, Popov built a version of the receiver that was capable of automatically recording lightning strikes on paper rolls. Popov's system was eventually extended to function as a wireless telegraph, with a Morse key attached to the transmitter. There's some dispute regarding the first public test of this design. It is frequently stated that Popov used his radio to send a Morse code message over a distance of 250 m in 26 March 1896 (three months before Marconi's patent was filed). However, contemporary confirmations of this transmission are lacking. It is more likely that said experiment took place in December 1897.
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 (40 km) away at Kymi (nowadays Kotka) on the Finnish coast. Later Popov experimented with ship-to-shore communication. Popov died in 1905 and his claim was not pressed by the Russian government until 1945.
In May–June 1899, Julio Cervera Baviera worked to develop his own system. After visiting Marconi’s radiotelegraphic installations on the English Channel, he began collaborating with Marconi on resolving the problem of a wireless communication system, obtaining some patents by the end of 1899. Cervera, who worked with Marconi and his assistant, George S. Kemp, in 1899, resolved the issues with their wireless telegraph. He obtained his first patents prior to the end of that year.
Guglielmo Marconi studied at the Leghorn Technical School, and acquainted himself with the published writings of Professor Augusto Righi of the University of Bologna. In 1894, Sir William Preece delivered a paper to the Royal Institution in London on electric signalling without wires. In 1894 at the Royal Institution lectures, Lodge delivers "The Work of Hertz and Some of His Successors". Marconi is said to have read, while on vacation in 1894, about the experiments that Hertz did in the 1880s. Marconi also read about Tesla's work. It was at this time that Marconi began to understand that radio waves could be used for wireless communications. 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 1.5 miles (2.4 km) at the end of 1895.
By 1896, 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 his research, demonstrations and patents. Marconi's later practical four-tuned system was pre-dated by N. Tesla, Oliver Lodge, and J. S. Stone. He filed a patent on his earliest system with the British Patent Office on June 2, 1896.
Marconi was awarded a patent for radio with British patent No. 12,039, Improvements in Transmitting Electrical Impulses and Signals and in Apparatus There-for. The complete specification was filed March 2, 1897. This was Marconi's initial patent for the radio, though it used various earlier techniques of various other experimenters (primarily Tesla) and resembled the instrument demonstrated by others (including Popov). During this time spark-gap wireless telegraphy was widely researched. In July, 1896, Marconi got his invention and new method of telegraphy to the attention of Preece, then engineer-in-chief to the British Government Telegraph Service, who had for the previous twelve years interested himself in the development of wireless telegraphy by the inductive-conductive method. On June 4, 1897, he delivered "Signalling through Space without Wires". Preece devoted considerable time to exhibiting and explaining the Marconi apparatus at the Royal Institution in London, stating that Marconi invented a new relay which had high sensitiveness and delicacy.
In 1896, Bose went to London on a lecture tour and met Marconi, who was conducting wireless experiments for the British post office. The Marconi Company Ltd. was founded by Marconi in 1897, known as the Wireless Telegraph Trading Signal Company. Also in 1897, Marconi established the radio station at Niton, Isle of Wight, England. Marconi's wireless telegraphy was inspected by the Post Office Telegraph authorities; they made a series of experiments with Marconi's system of telegraphy without connecting wires, in the Bristol Channel. The October wireless signals of 1897 were sent from Salisbury Plain to Bath, a distance of 34 miles (55 km). Marconi's reputation is largely based on the making of his law (1897), and other accomplishments in radio communications and commercializing a practical system.
Other experimental stations were established at Lavernock Point, near Penarth; on the Flat Holmes, an island in mid-channel, and at Brean Down, a promontory on the Somerset side. Signals were obtained between the first and last-named points, a distance of, approximately, 8 miles (13 km). The receiving instrument used was a Morse inkwriter of the Post Office pattern. In 1898, Marconi opened a radio factory in Hall Street, Chelmsford, England, employing around 50 people. In 1899, Marconi announced his invention of the "iron-mercury-iron coherer with telephone detector" in a paper presented at Royal Society, London.
In May, 1898, communication was established for the Corporation of Lloyds between Ballycastle and the Lighthouse on Rathlin Island in the North of Ireland. In July, 1898, the Marconi telegraphy was employed to report the results of yacht races at the Kingston Regatta for the Dublin Express newspaper. A set of instruments were fitted up in a room at Kingstown, and another on board a steamer, the Flying Huntress. The aerial conductor on shore was a strip of wire netting attached to a mast 40 feet (12 m) high, and several hundred messages were sent and correctly received during the progress of the races.
At this time His Majesty King Edward VII, then Prince of Wales, had the misfortune to injure his knee, and was confined on board the royal yacht Osltorm in Cowes Bay. Marconi fitted up his apparatus on board the royal yacht by request, and also at Osborne House, Isle of Wight, and kept up wireless communication for three weeks between these stations. The distances covered were small; but as the yacht moved about, on some occasions high hills were interposed, so that the aerial wires were overtopped by hundreds of feet, yet this was no obstacle to communication. These demonstrations led the Corporation of Trinity House to afford an opportunity for testing the system in practice between the South Foreland Lighthouse, near Dover, and the East Goodwin Lightship, on the Goodwin Sands. This installation was set in operation on December 24, 1898, and proved to be of value. It was shown that when once the apparatus was set up it could be worked by ordinary seamen with very little training.
At the end of 1898 electric wave telegraphy established by Marconi had demonstrated its utility, especially for communication between ship and ship and ship and shore. Electric wave telegraphy had the advantages as follows:
- Transmission worked as well by night as by day, and in bad weather, fogs, or storms, as well as in fair weather; provided that the proper insulation of the aerial wire or elevated conductor was maintained.
- In certain electrical conditions of the atmosphere, and during thunderstorms, some difficulty was usually found in working, owing to the atmospheric discharges affecting the sensitive tube, and therefore making stray marks on the Morse tape of the printer, but seldom sufficient to interrupt communication altogether.
- The interposition of high hills, trees, or the curvature of the earth did not prevent communication, though slightly affecting the power required. It worked particularly well over sea surface, and between ships and shore stations.
- The apparatus could be set up and handled by any ordinary telegraphist, and the record was made on paper strip in the usual Morse code.
- Transmission easily covered distances far beyond those feasible or attained by other systems of wireless telegraphy.
- Lastly, the apparatus required was by no means costly, and, with the exception of the mast required for upholding the aerial wire, it occupied but little space, and was particularly adapted for use on board ship.
The Haven Hotel station and Wireless Telegraph Mast was where much of Marconi's research work on wireless telegraphy was carried out after 1898. In 1899, he transmitted messages across the English Channel. Also in 1899, Marconi delivered "Wireless Telegraphy" to the Institution of Electrical Engineers. In addition, in 1899, W. H. Preece delivers "Aetheric Telegraphy", stating that the experimental stage in wireless telegraphy had been passed in 1894 and inventors were then entering the commercial stage. Preece, continuing in the lecture, details the work of Marconi and other British inventors. In October, 1899, the progress of the yachts in the international race between the Columbia and Shamrock was successfully reported by aerial telegraphy, as many as 4,000 words having been (as is said) despatched from the two ship stations to the shore stations. Immediately afterward the apparatus was placed by request at the service of the United States Navy Board, and some highly interesting experiments followed under Marconi's personal supervision. The Marconi Company was renamed Marconi's Wireless Telegraph Company in 1900.
In 1901, Marconi claimed to have received daytime transatlantic radio frequency signals at a wavelength of 366 metres (820 kHz). Marconi established a wireless transmitting station at Marconi House, Rosslare Strand, Co. Wexford in 1901 to act as a link between Poldhu in Cornwall and Clifden in Co. Galway. His announcement on 12 December 1901, using a 152.4-metre (500 ft) kite-supported antenna for reception, stated that the message was received at Signal Hill in St John's, Newfoundland (now part of Canada) via signals transmitted by the company's new high-power station at Poldhu, Cornwall. The message received had been prearranged and was known to Marconi, consisting of the Morse letter 'S' - three dots. Bradford has recently contested the reported success, however, based on theoretical work as well as a reenactment of the experiment. It is now well known that long-distance transmission at a wavelength of 366 meters is not possible during the daytime, because the skywave is heavily absorbed by the ionosphere. It is possible that what was heard was only random atmospheric noise, which was mistaken for a signal, or that Marconi may have heard a shortwave harmonic of the signal. The distance between the two points was about 3,500 kilometres (2,200 mi).
The Poldhu to Newfoundland transmission claim has been criticized. There are various science historians, such as Belrose and Bradford, who have cast doubt that the Atlantic was bridged in 1901, but other science historians have taken the position that this was the first transatlantic radio transmission. Critics have claimed that it is more likely that Marconi received stray atmospheric noise from atmospheric electricity in this experiment. The transmitting station in Poldhu, Cornwall used a spark-gap transmitter that could produce a signal in the medium frequency range and with high power levels.
Marconi transmitted from England to Canada and the United States. In this period, a particular electromagnetic receiver, called the Marconi magnetic detector or hysteresis magnetic detector, was developed further by Marconi and was successfully used in his early transatlantic work (1902) and in many of the smaller stations for a number of years. In 1902, a Marconi station was established in the village of Crookhaven, County Cork, Ireland to provide marine radio communications to ships arriving from the Americas. A ship's master could contact shipping line agents ashore to enquire which port was to receive their cargo without the need to come ashore at what was the first port of landfall. Ireland was also, due to its western location, to play a key role in early efforts to send trans-Atlantic messages. Marconi transmitted from his station in Glace Bay, Nova Scotia, Canada across the Atlantic, and on 18 January 1903 a Marconi station sent a message of greetings from Theodore Roosevelt, the President of the United States, to the King of the United Kingdom, marking the first transatlantic radio transmission originating in the United States
In 1904, Marconi opened the ocean daily newspaper, the Cunard Daily Bulletin, on the R.M.S. "Campania." At the start, the passing events were printed in a little pamphlet of four pages called the Cunard Bulletin. The title would read Cunard Daily Bulletin, with subheads for "Marconigrams Direct to the Ship." All the passenger ships of the Cunard Company are fitted with Marconi's system of wireless telegraphy, by means of which constant communication was kept up, either with other ships or with land stations on the eastern or western hemisphere. The RMS Lucania, Oct., 1903, with Marconi on board, was the first vessel to hold communication with both sides of the Atlantic. The Cunard Daily Bulletin, a thirty-two page illustrated paper published on board these boats, recorded news received by wireless telegraphy, and is first ocean newspaper. In August, 1903, in agreement was made with the British Government by which the Cunard Co. were to build two steamers, to be, with all other Cunard ships, at the disposal of the British Admiralty for hire or purchase whenever they may be required, the Government lending the company £2,600,000 to build the ships and granting them a subsidy £150,000 a year. One was the RMS Lusitania and the RMS Mauritania.
In June and July 1923, Marconi's shortwave transmissions were completed during nights on 97 meters from Poldhu Wireless Station, Cornwall, to his yacht Elettra in the Cape Verde Islands. In September 1924, Marconi transmitted during daytime and nighttime on 32 meters from Poldhu to his yacht in Beirut. Marconi, in July 1924, entered into contracts with the British General Post Office (GPO) to install telegraphy circuits from London to Australia, India, South Africa and Canada as the main element of the Imperial Wireless Chain. The UK-to-Canada shortwave "Beam Wireless Service" went into commercial operation on 25 October 1926. Beam Wireless Services from the UK to Australia, South Africa and India went into service in 1927. Electronic components for the system were built at Marconi's New Street wireless factory in Chelmsford.
Marconi would jointly receive the 1909 Nobel Prize in Physics with Karl Ferdinand Braun for contributions to the existing radio sciences. Marconi's 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. 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. The United States Supreme Court, decision of MARCONI WIRELESS T. CO. OF AMERICA v. U.S., 320 U.S. 1 (1943) stated that “Marconi's reputation as the man who first achieved successful [transatlantic] radio transmission … is not here in question” this statement is followed by “Marconi's patent involved no invention over Lodge, Tesla, and Stone”. The 1943 decision didn't overturn Marconi's original patents, or his reputation as the first person to develop practical radiotelegraphic communication. It just said that the adoption of adjustable transformers in the transmitting and receiving circuits, which was an improvement of the initial invention, was anticipated by patents issued to Oliver Lodge and John Stone. (This decision wasn't unanimous).
The United States Navy Board had issued a 1899 report on the results of investigations of the Marconi system of wireless telegraphy. The report, Notes On The Marconi Wireless Telegraphy was published in full in the Electrician, and from it the following statements concerning the efficiency of the system have been taken: It was well adapted for use in squadron signalling under conditions of rain, fog, darkness and motion of speed. Wind, rain, fog, and other conditions of weather do not affect the transmission through space, but dampness may reduce the range, rapidity, and accuracy by impairing the insulation of the aerial wire and the instruments. Darkness has no effect. When two transmitters are sending at the same time, all the receiving wires within range receive the impulses from transmitters, and the tapes, although unreadable, show unmistakably that such double sending was taking place. In every case, under a great number of varied conditions, the attempted interference was complete. Marconi, although he stated to the Board before these attempts were made that he could prevent interference, never explained how nor made any attempt to demonstrate that it could be done. Between large ships (heights of masts 130 feet (40 m) and 140 feet (43 m)) and a torpedo-boat (height of mast 45 feet (14 m)), across open water, signals can be read up to 7 miles (11 km) on the torpedo-boat and 85 miles (137 km) on the ship. Communication might be interrupted altogether when tall buildings of iron framing intervene. The rapidity was not greater than twelve words per minute for skilled operators. The sending apparatus and wire would injuriously affect the compass if placed near it. The exact distance were not known, and would be determined by experiment. The system was adapted for use on all vessels of the navy, including torpedo-boats and small vessels, as patrol boats, scout boats, and despatch boats, but it was impracticable in a small boat. For landing parties the only feasible method of use would be to erect a pole on shore and then communicate with the ship. The system could be adapted to the telegraphic determination of differences of longitude in surveying. The Board respectfully recommended that the system be given a trial in the United States Navy.
The HMS Hector became the first British warship to have wireless telegraphy installed when she conducted the first trials of the new equipment for the Royal Navy. Starting in December 1899, the HMS Hector and HMS Jaseur were outfitted with wireless equipment. In 1901, HMS Jaseur received signals from the Marconi transmitter on the Isle of Wight and from the HMS Hector (25 January).
John Stone Stone labored as an early telephone engineer and was influential in developing wireless communication technology, and holds dozens of key patents in the field of "space telegraphy". Patents of Stone for radio, together with their equivalents in other countries, form a very voluminous contribution to the patent literature of the subject. More than seventy United States patents have been granted to this patentee alone. In many cases these specifications are learned contributions to the literature of the subject, filled with valuable references to other sources of information. A complete analysis of Stone's specifications would occupy too much space. Broadly speaking, they may be divided into four classes:
- Those concerned with proposed methods for the achievement of syntonic telegraphy, or the isolation of receiving stations or protection of receivers from the action of vagrant waves.
- Those describing forms of electric wave detector or cymoscope.
- Those covering the construction of various forms of transmitting and receiving circuit, and the production of continuous trains of waves.
- Miscellaneous specifications covering devices proposed for localizing the direction of the arriving waves and other matters.
Stone has had issued to him a large number of patents embracing a method for impressing oscillations on a radiator system and emitting the energy in the form of waves of predetermined length whatever may be the electrical dimensions of the oscillator. On February 8, 1900, he filed for a selective system in U.S. Patent 714,756. In this system, two simple circuits are associated inductively, each having an independent degree of freedom, and in which the restoration of electric oscillations to zero potential the currents are superimposed, giving rise to compound harmonic currents which permit the resonator system to be syntonized with precision to the oscillator. Stone's system, as stated in U.S. Patent 714,831, developed free or unguided simple harmonic electromagnetic signal waves of a definite frequency to the exclusion of the energy of signal waves of other frequencies, and an elevated conductor and means for developing therein forced simple electric vibrations of corresponding frequency. In these patents Stone devised a multiple inductive oscillation circuit with the object of forcing on the antenna circuit a single oscillation of definite frequency. In the system for receiving the energy of free or unguided simple harmonic electromagnetic signal waves of a definite frequency to the exclusion of the energy of signal waves of other frequencies, he claimed an elevated conductor and a resonant circuit associated with said conductor and attuned to the frequency of the waves, the energy of which is to be received. A coherer made on what is called the Stone system was employed in some of the portable wireless outfits of the United States Army. The Stone Coherer has two small steel plugs between which are placed loosely packed carbon granules. This is a self-decohering device; though not as sensitive as other forms of detectors it is well suited to the rough usage of portable outfits.
In late 1886, Reginald A. Fessenden began working directly for Thomas Edison at the inventor's new laboratory in West Orange, New Jersey. Fessenden quickly made major advances, especially in receiver design, as he worked to develop audio reception of signals. Fessenden's initial United States patents were U.S. Patent 706,735 and U.S. Patent 706,736 and are companion patents. One concerns the methods and the other the devices of the same system. The United States Weather Bureau began, early in 1900, a systematic course of experimentation in wireless telegraphy, employing him as a specialist. Fessenden evolved the heterodyne principle here where two signals combined to produce a third signal.
In 1900, construction began on a large radio transmitting dynamo. Fessenden, experimenting with a high-frequency spark transmitter, successfully transmitted speech on December 23, 1900 over a distance of about 1.6 kilometres (0.99 mi), the first audio radio transmission. Early in 1901 the Weather Bureau officially installed Fessenden at Wier's Point, Roanoke Island, North Carolina, and he made experimental transmissions across water to a station located about 5 miles (8.0 km) west of Cape Hatteras, the distance between the two stations being almost exactly 50 miles (80 km). A dynamo of 1 kW output at 10 kilohertz was built in 1902. The credit for the development of this machine is due to Charles Proteus Steinmetz, Caryl D. Haskins, Ernst Alexanderson, John T. H. Dempster, Henry Geisenhoner, Adam Stein, Jr., and F. P. Mansbendel.
In a paper written by Fessenden in 1902, it was asserted that important advances had been made, one of which was overcoming largely the loss of energy experienced in other systems. He also declared that syntony was not safely selecting,[clarification needed] but that he had discovered several methods which were. In an interview with a New York Journal correspondent, Fessenden stated that in his early apparatus he did not use an air transformer at the sending end, nor a concentric cylinder for emitters and antennae, and had used capacity, but arranged in a manner entirely different from that in other systems, and that he did not employ a coherer or any form of imperfect contact. His apparatus was of solid metal, and, according to Fessenden, acted under a physical law entirely different from that which governs the receiving devices of Marconi. Fessenden asserted that he had paid particular attention to selective and multiplex systems, and was well satisfied with the results in that direction. On August 12, 1902, 13 patents were issued to Fessenden, covering various methods, devices, and systems for signaling without wires. These patents involved many new principles, the chef-d'oeuvre of which was a method for distributing capacity and inductance instead of localizing these coefficients of the oscillator as in previous systems.
By the summer of 1906, a machine producing 50 kilohertz was installed at the Brant Rock station, and in the fall of 1906, the electric alternating dynamo was working regularly at 75 kilohertz, with an output of 0.5 kW. Fessenden used this for wireless telephoning to Plymouth, a distance of approximately 11 miles (18 km). In the following year machines were constructed having a frequency of 96 kilohertz and outputs of 1 kW and 2 kW. Fessenden believed that the damped wave-coherer system was essentially and fundamentally incapable of development into a practical system. He would employ a two-phase high frequency dynamo method and the continuous production of waves with changing constants of sending circuit. Fessenden would also use duplex and multiplex commutator methods. On Dec. 11, 1906, operation of the wireless transmission in conjunction with the wire lines took place. In July 1907 the range was considerably extended and speech was successfully transmitted between Brant Rock and Jamaica, Long Island, a distance of nearly 200 miles (320 km), in daylight and mostly over land, the mast at Jamaica being approximately 180 feet (55 m) high.
In November 1904, John Ambrose Fleming invented the two-electrode vacuum-tube rectifier, which he called the Fleming oscillation valve. He would later patent this invention. This "Fleming Valve" was sensitive and reliable, and so it replaced the crystal diode used in receivers used for long-distance wireless communication. It had an advantage, that it could not be permanently injured or set out of adjustment by any exceptionally strong stray signal, such as those due to atmospheric electricity. Fleming earned a Hughes Medal in 1910 for his electronic achievements.
Fleming recognized the use of the rectifying properties of a wireless tube for the indication of high frequency oscillations, and used it as a electromagnetic detector. On November 7, 1905, he would be granted U.S. Patent 803,684. Marconi used this device as a radio detector, also.[when?] His detector was par excellence for large antenna or high-power stations.
The Supreme Court of the United States would eventually invalidate the patent because of an improper disclaimer and, additionally, maintained the technology in the patent was known art when filed. This invention was the first vacuum tube. Fleming's diode was used in radio receivers for many decades afterward, until it was superseded by improved solid state electronic technology more than 50 years later.
Lee De Forest had an interest in wireless telegraphy and he invented the Audion in 1906. He was president and secretary of the De Forest Radio Telephone and Telegraph Company (1913). The De Forest System was adopted by the United States Government, and had been demonstrated to other Governments including those of Great Britain, Denmark, Germany, Russia, and British Indies, all of which purchased De Forest apparatus previous to the Great War. De Forest is one of the fathers of the "electronic age", as the Audion helped to usher in the widespread use of electronics.
De Forest made the Audion tube from a vacuum tube. He also made the "Oscillion", an undamped wave transmitter. He developed the De Forest method of wireless telegraphy and founded the American De Forest Wireless Telegraph Company. De Forest was a distinguished electrical engineer and the foremost American contributor to the development of wireless telegraphy and telephony. The elements of his device takes relatively weak electrical signals and amplifies them. The Audion Detector, Audion Amplifier, and the "Oscillion" transmitter had furthered the radio art and the transmission of written or audible speech. In World War I, the De Forest system was a factor in the efficiency of the United States Signal Service, and was also installed by the United States Government in Alaska.
Radio invention timeline
Below is a brief selection of important events and individuals related to the development of radio, from 1860 to 1910 (click to show timeline).
- Edwin Howard Armstrong, Greenleaf Whittier Pickard, Ernst Alexanderson, Archie Frederick Collins
- Radio communication system, Timeline of radio, Oldest radio station, Birth of public radio broadcasting, Crystal radio
- Radio People, Radio Pioneers, Discovery and invention controversies
- List of persons considered father or mother of a field, Radiotelegraph and Spark-Gap Transmitters, The Great Radio Controversy, Induction coil, Ruhmkorff coil, Poldhu, Alexanderson alternator, De Forest tube
- Brother Potamian (1913). "Francesco Zantedeschi article at the Catholic Encyclopedia". Wikisource. Retrieved 2007-06-16.
- Electrician, May 5, 1899.
- Scientific Writings of Joseph Henry, Smithsonian Institution.
- 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.)
- Helmholz "Erhaltung der Kraft", Berlin, 1847.
- Kelvin, Philosophical Magazine, June, 1853.
- Transactions, Volume 27, Part 1 By American Institute of Electrical Engineers
- 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". New Scientist. Retrieved 2008-09-06.
- "Electromagnetism". IEEE History Center. 2011. Retrieved 2011-06-20.
- Nahin, P.J., Spectrum, IEEE, Volume 29, Issue 3, March 1992 Page(s):45–
- "Wireless telegraphy". Scientific American, June 19, 1897, page 386. Uses the term to connote "aether's conduction".
- "The Slaby system of wireless duplex telegraphy". Scientific American, March 9, 1901, pages 146-147. Uses the term to connote "aether's conduction".
- Christopher H. Sterling (ed.). Encyclopedia of Radio, Volume 1. Page 831
- Thomas H. Lee. The Design of CMOS Radio-Frequency Integrated Circuits. Page 33-34.
- Carson, Mary Kay (2007) Alexander Graham Bell: Giving Voice To The World, Sterling Biographies, New York, NY 10016: Sterling Publishing Co., Inc.. pp. 76-78. ISBN 978-1-4027-3230-0. OCLC 182527281
- Phillipson, Donald J.C., and Neilson, Laura Bell, Alexander Graham, The Canadian Encyclopedia online. Retrieved 2009-08-06
- History of the Radio Industry in the United States to 1940 by Carole E. Scott, State University of West Georgia
- Collegio Pio-Latino-Americano Pontificio
- Dias, A., & Raposo, L. (1907). The Brazil of to-day: A book of commercial, political and geographical information on Brazil; impressions of voyage, descriptive and picturesque data about the principal cities, prominent men and leading events of our days, with illustrations and statistics. Nivelles: Lanneau & Despret, printers.
- Arthur Dias, in his book "The Brazil of to-day", refers to de Moura, describing, among other things, the following:
[. . . ] as soon as they arrived in São Paulo in 1893, began making preliminary experiments in order to achieve its purpose of conveying the voice of humans to a distance of 8, 10 or 12 miles, without wires.
- "Father Roberto Landell de Moura". highfields-arc.co.uk.
- U.S. Patent 771,917 and U.S. Patent 775,337.
- U.S. Patent 775,846 claims a set of Hertz wave antennae, a source of cathodic waves, and a source of actinic waves, means whereby the changes of a pre-arranged code may be impressed upon one or more sets of the waves, and means to direct them toward a distant station.
- Feddersen, Bernhard Wilhelm, geb. 26. März 1832 in Schleswig, Sohn des vorhergenannten B. Feddersen, No. 475, studirte Naturwissenschaften und war eine Zeitlang Assistent im naturwissenschaftlichen Institut unter Prof. Karstens Leitung, wurde 1858 dr. philos. in Kiel; zur Zeit Privatdocent in Leipzig. (tr., Feddersen, Bernhard Wilhelm, born 26 March 1832 in Schleswig, the son of the aforementioned B. Feddersen, no. 475, studied science and was for a time assistant in a scientific institute under Prof. Karsten's line was, in 1858 dr. philos in Kiel, at the time Privatdocent in Leipzig.) (Lexicon of the Schleswig-Holstein-Lauenburg and Eutin manner between writers from 1829 to mid-1866. Edward Alberti (1867).)
- Von Bezold, Poggendorff's Annalen, 140, p. 541.
- "Scientific Serials". Nature 3 (63): 216–217. 12 January 1871. Bibcode:1871Natur...3..216.. doi:10.1038/003216a0.
- Journal Franklin Institute, April 1876.
- Fitzgerald "On a method of producing Electromagnetic Disturbances of comparatively short wave lengths". Report of British Association, 1883.
- Prof. D. E. Hughes' Research in Wireless Telegraphy, The Electrician, Volume 43, 1899, pages 35, 40-41, 93, 143-144, 167, 217, 401, 403, 767
- A History of Wireless Telegraphy (2nd edition, revised), J.J. Fahie, 1899, pages 289-316:
- A History of Wireless Telegraphy by J.J.Fahie, 1901.
- Wireless telegraphy: a popular exposition By George William von Tunzelmann. The Office of "Knowledge", 1902. Pages 60–65.
- SOME POSSIBILITIES OF ELECTRICITY, The Fortnightly Review, Volume 57, William Crookes, February 1, 1892, pages 174-176
- The Story of Wireless Telegraphy by A. T. Story
- Anon (January 26, 1900). "Obituary: David Edward Hughes". The ELECTRICIAN (London): 457–458. Retrieved June 29, 2009., The Electrician, Volume 45
- Anon. "88. David Edward Hughes". 100 Welsh Heroes. Culturenet Cymru. Retrieved June 30, 2009.
- Globe, May 12, 1899.
- Massie, W. W., & Underhill, C. R. (1911). Wireless telegraphy and telephony popularly explained. New York: D. Van Nostrand.
- "Annalen der Physik und Chemie". Sparkmuseum.com. Retrieved 2012-04-15.
- Hertz, H. (1893). Electric waves: Being researches on the propagation of electric action with finite velocity through space. Dover Publications.
- Electric waves; being research on the propagation of electric action with finite velocity through space by Heinrich Rudolph Hertz, Daniel Evan Jones 1 Review Macmillan and co., 1893. Pages1 - 5
- "Hertzian Waves (1901)". Retrieved 2008-08-11.
- "Hertz wave". Tfcbooks.com. Retrieved 2010-01-31.
- Eugenii Katz, "Heinrich Rudolf Hertz". Biographies of Famous Electrochemists and Physicists Contributed to Understanding of Electricity, Biosensors & Bioelectronics.
- Donahoe's Magazine, March, 1893.
- Variations of Conductivity under Electrical Influences, By Edouard Branly. Minutes of proceedings of the Institution of Civil Engineers, Volume 103 By Institution of Civil Engineers (Great Britain) Page 481 (Contained in, Comptes rendus de I'Acade'mie des Sciences, Paris, vol. cii., 1890, p. 78.)
- On the Changes in Resistance of Bodies under Different Electrical Conditions. By E. Branly. Minutes of proceedings, Volume 104 By Institution of Civil Engineers (Great Britain). 1891. Page 416 (Contained in, Comptes Rendus de l'Academie des Sciences, Paris, 1891, vol. exit., p. 90.)
- Experiments on the conductivity of insulating bodies, By M. Edouard Branly, M.D. Philosophical magazine. Taylor & Francis., 1892. Page 530 (Contained in, Comples Rendus de l' Academic des Sciences, 24 Nov. 1890 and 12 Jan. 1891, also, Bulletin de la Societi internationals d'electriciens, no. 78, May 1891)
- Increase of Resistance of Radio-conductors. E. Branly. (Comptes Rendus, 130. pp. 1068-1071, April 17, 1900.)
- "Wireless Telegraphy". Modern Engineering Practice VII. American School of Correspondence. 1903. p. 10.
- although Dr. Branly himself termed it a radio-conductor.
- Maver's wireless telegraphy: theory and practice By William Maver (jr.)
- United States Naval Institute (1902). Proceedings: Volume 28, Part 2. Page 443.
- Rupert Stanley (1914). "Detectors". Text-book on wireless telegraphy 1. Longmans, Green. p. 217.
- "Nikola Tesla". ieeeghn.org
- U.S. Patent 447,921, Tesla, Nikola, "Alternating Electric Current Generator".
- Tesla: man out of time By Margaret Cheney. Page 357.
- Journal of the Franklin Institute, Volume 136 By Persifor Frazer, Franklin Institute (Philadelphia, Pa.)
- Fleming, J. A. (1919). The principles of electric wave telegraphy and telephony. London: Longmans, Green. Page 232.
- A. Oberbeck, "Ueber den Vcrlauf der Klcctrischen Schwingungen bei den Tesla'schen Versuchen," (tr., Over the course of the electric vibrations of Tesla's experiments) Wied. Ann. der Physii., 1895, vol. 55, p. B23.
- G. W. Pierce, "On Experiments on Resonance in Wireless Telegraph Circuits, Physical Review, vol. 24, February 1902, p. 152.
- Those two patents were issued in early 1900.
- 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.)
- These are known as electric circuit controllers.
- U.S. Patent 609,245, U.S. Patent 609,246, U.S. Patent 609,247, U.S. Patent 609,250, U.S. Patent 609,251, and U.S. Patent 611,719
- Corum, K. L., and J. F. Corum, "Tesla's Colorado Springs Receivers (A Short Introduction)".
- 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".
- Trevert, E. (1904). The A.B.C. of wireless telegraphy: A plain treatise on Hertzian wave signaling; embracing theory, methods of operation, and how to build various pieces of the apparatus employed. Lynn, Mass: Bubier Pub. Co. Page 23.
- ""The True Wireless" by Nikola Tesla". Tfcbooks.com. 1932-09-11. Retrieved 2012-04-15.
- In La, F. R. M., La, F. R. M., Handy, W. M., & Higgins, C. (1906). The making of America. Chicago: Making of America Pg 163
- "Experiments on the Discharge of Leyden Jars." By Oliver J. Lodge, F.R.S. Received May 2, 1891.
- The principles of electric wave telegraphy By John Ambrose Fleming
- Proceedings, Volume 14 By Royal Institution of Great Britain. Pg 321+
- History of Communications-Electronics in the United States Navy, Captain Linwood S. Howeth, USN (Retired), 1963, pages 15-23: CHAPTER II Birth of Science of Radio and Development of Usable Components
- Sir Oliver Lodge Invented Radio - Not Marconi".
- In 1895, the Royal Society recognized this scientific breakthrough at a special ceremony at Oxford University. For more information, see Past Years: An Autobiography, New York: Charles Scribner's Sons, p231.
- Wiedemann's Annalen, vol. xlii. p. 142 (Jan. 1801)
- Archives des Sciences Physiques et Naturelles Geneve, 1890, t. xxiii, p. 113
- On the sudden acquisition of conduction power by a series of discrete metallic particles, By Oliver Lodge. Proceedings: Volume 23 Institution of Electrical Engineers (1895). Page 252. (Contained in, Philosophical Magazine, Vol. 37, No. 224, p. 94.)
- Peter Rowlands (ed.) and J. Patrick Wilson (ed.) "Oliver Lodge and the Invention of Radio" ISBN 1-873694-02-4
- Sir O. J. Lodge, "The Work of Hertz", Proceedings Royal Institution, June 1, 1904, Vol. 14, page 321.
- Transactions, Volume 27, Part 1 By American Institute of Electrical Engineers. Page Pg 558+
- Filings coherer in hydrogen under reduced pressure
- This in a note added July, 1894
- The connection of the coherer to a grounded conductor; i.e., a gas pipe system.
- The method of making the coherer so connected respond by setting up oscillations in a separate grounded system, i.e., a hot-water pipe system, in another part of the building.
- The method of detecting distant thunder storms by connecting the coherer to a grounded gas pipe system
- speaking galvanometer
- Papers by command, Volume 8 By Great Britain. Parliament. House of Commons. Page 151.
- "Jagadish Chandra Bose". www.ieeeghn.org.
- "Jagadish Chandra Bose" (PDF). Pursuit and Promotion of Science: The Indian Experience (Chapter 2). Indian National Science Academy. 2001. pp. 22–25. Retrieved 200ref>Massie, W. W., 7-03-12.
- "Jagadish Chandra Bose, ieeeghn.org.
- Sir Patrick Geddes. The life and work of Sir Jagadis C. Bose. Longmans, Green, 1920. 61 - 65.
- 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.
- The life and work of Sir Jagadis C. Bose By Sir Patrick Geddes. "The Response of Plants to Wireless Stimulation"
- The Wireless Age, Volume 5. Page 709 - 713.
- The Electrical engineer, Volume 23. Page 159.
- Wireless telegraphy By Jonathan Adolf Wilhelm Zenneck. Pg 175
- The Electrical magazine and engineering monthly, Volume 1 edited by Theodore John Valentine Feilden (1904). Page 508.
- The Electrical magazine and engineering monthly, Volume 1 edited by Theodore John Valentine Feilden. Page 508.
- Marconi had adopted this way of increasing the available energy, the potentials attainable by his now familiar arrangement being exceedingly high, but the method is wasteful owing to the length of spark gap used.
- This method was described by Braun some time ago.
- "The Nobel Prize in Physics 1909 Guglielmo Marconi, Ferdinand Braun". Nobelprize.org. 1918-04-20. Retrieved 2012-04-15.
- M. Radovsky (2001). Alexander Popov Inventor of Radio. Page 44
- "Alexander Popov in Chicago." Soviet Life (Oct. 1985): 27-28.
- A.S. Popov. "On the relation between metal powder and electric oscillations".Zh. Russ. Fiz.-Khim. Obshchestva (Physics, pt 1) 1895, 27, pp 259-260.
- A.S. Popov. "Apparatus for the detection and recording of electrical oscillations." Zh. Russ. Fiz.-Khim. Obshchestva (Physics, pt 1) 1896, 28, pp 1-14
- "An Application of the Coherer." The Electrician, 1897.
- Journal Russian Physico-Chemical Society, Voi.27. April 25, 1895
- Transactions, Volume 27, Part 1 By American Institute of Electrical Engineers. Pg 558-559.
- "Early Radio Transmission Recognized as Milestone". IEEE. Retrieved July 16, 2006.
- D.T. Emerson, "The work of Jagadis Chandra Bose: 100 years of mm-wave research". National Radio Astronomy Observatory, February 1998.
- "Popov's Contribution to the Development of Wireless Communication, 1895". IEEE History Center, IEEE Milestone.
- "Russia's Popov: Did he "invent" radio?". The First Electronic Church of America.
- A. S. Popov, " Apparatus for detection and registration of electrical vibrations ", Journal Russian Physico-Chemical Society, Vol. 28, Dec. 1895.
- "Л.Н.Никольский. Кто "изобрел" радио?". Oldradioclub.ru. Retrieved 2012-04-15.
- Research by professor Ángel Faus credits Baviera with inventing the radio in 1902 and patenting it in England, Germany, Belgium, and Spain. see The Spaniard Julio Cervera Baviera, and not Marconi, was the inventor of the radio, according to professor Ángel Faus. University of Navarra.
- Miessner, B. F. (1916). Radiodynamics: The wireless control of torpedoes and other mechanisms. New York: D. Van Nostrand Co. Page 31-32
- "Electric signalling without wires", paper by W. H. Preece
- Journal of the Society of Arts, Volume 42 By Society of Arts (Great Britain). 1894. Pg 274+
- Haydn's dictionary of dates and universal information relating to all ages and nations By Joseph Haydn, Benjamin Vincent. G. P. Putnam's sons, 1904. page 413.
- The Wireless age. (1914). N.Y. [New York] City: Macroni Pub. Corp'n (Wireless Press). "Wireless as a Commercial Fact, From the Inventor's Testimony in the United States Court in Brooklyn. G. Marconi, Part III". Page 75.(cf. "I read parts of a book by Martin, entitled "Inventions, Researches and Writings of Nikola Tesla," published in 1894".)
- 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?"
- The dispute over patent rights between the Marconi Company and Tesla began in August, 1914, when the Marconi Company sued Fritz Lowenstein, a German engineer, alleging that certain wireless apparatus sold by him to the United States Navy was made in violation of the Marconi U.S. Patent 763,772. It was announced then 'that Tesla would testify for Lowenstein, alleging that the Lowenstein devices were developed from Tesla patents U.S. Patent 645,576 and U.S. Patent 649,621, which were granted prior to the Marconi patent. In the present suit, Tesla bases his action on the allegation that his two patents were granted in 1900, and that the Marconi patent was not granted until 1904. (Wireless world, Volume 3 By Wireless Society of London. s.n., 1915)
- WH Preece, "Signalling through Space without Wires," Proc. Roy. Inst. Lond., 1897, vol. xv. p. 467.
- Report of the Board of Regents By Smithsonian Institution. Board of Regents, United States National Museum, Smithsonian Institution. 1899. Pg 249+
- The principles of electric wave telegraphy By Sir John Ambrose Fleming Pg. 429
- source: Elements of radiotelegraphy By Ellery W. Stone
- Apparatus similar to that used by Marconi in 1897.
- Wireless telegraphy and telephony without wires By Charles Robert Gibson. Pg 79
- James Erskine-Murray (1907). A handbook of wireless telegraphy: its theory and practice, for the use of electrical engineers, students, and operators. Crosby Lockwood and Son. Page 39
- The Electrical review, Volume 40. IPC Electrical-Electronic Press, 1897. Page 715. Retrieved 2012-04-15.
- The Electrical world, Volume 29 Page 822. Retrieved 2012-04-15.
- Earlier, in 1885, a wired telephonic system was established here also. See, The Electrical review, Volume 17. Pg 81
- A summary of his work on wireless telegraphy up to the beginning of 1899 is given in a paper read by Marconi to the Institution of Electrical Engineers on March 2, 1899. See Journal of the li st. Elee. Eng., 1899, vol. 28, p. 273.
- The principles of electric wave telegraphy By Sir John Ambrose Fleming. Page 431-432.
- The Electrical engineer (1899). Volume 23. Pg 307, 342, 361, 368
- Journal of the Society of Arts, Volume 47 By Society of Arts (Great Britain). 1899. Page 519+
- A story of wireless telegraphy By Alfred Thomas Story. Pg 161
- Wireless telegraphy: its origins, development, inventions, and apparatus By Charles Henry Sewall, pg 144
- 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..
- 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. Retrieved 2008-08-09.
- "Marconi's Error: The First Transatlantic Wireless Telegraphy in 1901"
- In December, 1902, he established wireless telegraphic communication between Canada (Cape Breton) and England, the first message inaugurating the system being transmitted from the Governor General of Canada to King Edward VII, and a few weeks later a message inaugurating wireless connection between America (Cape Cod, Massachusetts) and Cornwall, England was transmitted from the President of the United States to the King of England. (Encyclopaedia of ships and shipping edited by Herbert B. Mason. The Shipping Encyclopaedia, 1908.)
- "Note on a Magnetic Detector of Electric Waves, which can be employed as a Eeceiver for Space Telegraphy." By G. Marconi, M.I.E.E. Communicated by Dr. J. A. Fleming, F.E.S. Received June 10, Read June 12, 1902. Proceedings of the Royal Society of London, Volume 70 By Royal Society (Great Britain). Pg 341
- Journal of the Society of Arts, Volume 51 By Society of Arts (Great Britain). Pg 761
- How to become a wireless operator. American technical society, 1918. Pg 202
- New Marconi Wireless Telegraph Apparatus. The Electrical world and engineer, Volume 40. Pg 91.
- "Marconi at Mizen Head Visitor Centre Ireland Visitor Attractions". Mizenhead.net. Retrieved 2012-04-15.
- The Inland printer, Volume 38 pg 389
- An almanack for the year of our Lord [...], Volume 39 By Joseph Whitaker, 1907.
- The Marconi company Departments 1912 - 1970 Martin Bates, accessed 2010-10-04
- United States., & Smith, W. A. (1912). "Titanic" disaster: Hearing before a subcommittee of the Committee on Commerce, United States Senate : Sixty-second Congress, second session, pursuant to S. Res. 283, directing the Committee to investigate the causes leading to the wreck of the White Star liner "Titanic" ... : [April 19-May 25, 1912]. Washington [D.C.: G.P.O.]
- "U.S. Supreme Court". Retrieved 2012-04-23.
- United States Naval Institute proceedings, Volume 25 By United States Naval Institute. Page 857
- Notes On The Marconi Wireless Telegraphy By Lieut. JB Blish, USN
- Locomotive engineers journal, Volume 44 By Brotherhood of Locomotive Engineers (U.S.). Pg 77
- The ship was sold for scrap in 1905.
- Ballard, G. A., Admiral (1980). The Black Battlefleet. Annapolis, MD: Naval Institute Press. ISBN 0-87021-924-3. pp. 158–59
- Captain Henry Jackson developed the tuned receiver.
- Fleming, J. A. (1906). The principles of electric wave telegraphy. London: Longmans, Green, and Co. Page 520.
- Wireless telegraphy: its history, theory and practice By Archie Frederick Collins. Page 164
- Maver's wireless telegraphy: theory and practice By William Maver (jr.). Page 126.
- Text-book on wireless telegraphy, Volume 1 By Rupert Stanley. Longmans, Green, 1919. Pg 300.
- filed December 15, 1899
- Wireless telegraphy: its origins, development, inventions, and apparatus By Charles Henry Sewall. page 114
- Wireless telegraphy: its origins, development, inventions, and apparatus By Charles Henry Sewall. pages 66–71.
- R. A. Fessenden (1909). "Wireless Telephony". Transactions of the American Institute of Electrical Engineers (New York: American Institute of Electrical Engineers). 27, Part 1.
- such as were employed by the Marconi Company
- While the telephone was used as a recorder of signals, he said he could also get good service from a siphon recorder.
- Assisted by H. R. Hadfield, J. W. Lee, F. P. Mansbendel, G. Davis, M. L. Wesco, A. Stein, Jr., H. Sparks, and Guv Hill.
- The regular operating frequency would be 81.7 kilohertz
- contained in U.S. Patent 793,649
- contained in U.S. Patent 793,649, U.S. Patent 706,747, U.S. Patent 706,742, U.S. Patent 727,747
- Governing by resonance was invented and patented by Kempster B. Miller, U.S. Patent 559,187, Feb. 25, 1896.
- contained in U.S. Patent 793,652
- An amusing instance may be mentioned as illustrating the incredulity with which the wireless telephone was received. Some of the local papers having published an account of the experiments with the schooner above referred to the following appeared under the heading "Current News and Notes" in the columns of a prominent technical journal, Nov. 10, 1906.
"A New Fish Story. — It is stated from Massachusetts that the wireless telephone has successfully entered into the deep sea fishing industry. For the last week experiments have been conducted by the wireless telegraph station at Brant Rock, which is equipped with a wireless telephone, with a small vessel stationed in the fleet of the South Shore fishermen, twelve miles out in Massachusetts Bay. Recently, it is asserted, the fishermen wished to learn the prices ruling in the Boston market. The operator on the wireless fitted boat called up Brant Rock and telephoned the fishermen's request. The land operator asked Boston by wire and the answer was forwarded back to the fishermen. This is a rather fishy fish story".
The doubt expressed was, however, only natural. Fessenden remembered the astonishment displayed by one of the company's new operators some months previously on placing the receiving telephone to his head while the vessel was almost out of sight of land and hearing the operator at the land station call his name and begin to talk to him.
- "Long Distance Wireless Telephony," The Electrician, Oct. 4, 1907.
- Fleming Valve patent U.S. Patent 803,684
- It was also called a thermionic valve, vacuum diode, kenotron, thermionic tube, or Fleming valve.
- The wonders of wireless telegraphy explained in simple terms for the non-technical reader By John Ambrose Fleming. Society for promoting Christian knowledge, 1914. Page 149.
- J. A. Fleming, Proc. Roy. Soc, Jan., 1905, p. 476
- The thermionic vacuum tube and its applications By Hendrik Johannes Van der Bijl
- "Misreading the Supreme Court: A Puzzling Chapter in the History of Radio". November 1998, Mercurians.org.
- "The Audion: A New Receiver for Wireless Telegraphy". Transactions of the American Institute of Electrical Engineers By American Institute of Electrical Engineers. Pg 735
- The Audion—Detector and Amplifier. Proceedings of the Institute of Radio Engineers, Volume 2 By Institute of Radio Engineers. Pg 15
- Statement of Dr. Lee de Forest, Radio Telephone Company, A Brief on the Proposed Resolution for Federal Regulation of Wireless. United States. (1910). Hearings before a subcommittee of the Committee on Naval Affairs of the House of Representatives on H.J. Resolution 95: A bill to regulate and control the use of wireless telegraphy and wireless telephony. Washington: Gov. Print. Off. Pg 75
- Industrial plant was located at 1391 Sedgwick Avenue in Bronx Borough, New York City.
- [[Charles Gilbert (treasurer)|]] was the treasurer of the company.
- Weiss, G., & Leonard, J. W. (1920). America's maritime progress. New York: New York marine news Co. Pg 254
- Anderson, L.I., "Priority in the Invention of Radio: Tesla vs. Marconi", Antique Wireless Association Monograph No. 4, March, 1980.
- Anderson, L.I., "John Stone Stone on Nikola Tesla's Priority in Radio and Continuous-Wave Radiofrequency Apparatus", The A.W.A. (Antique Wireless Association) Review, Vol. 1, 1986, pp. 18–41.
- Brand, W.E., "Rereading the Supreme Court: Tesla's Invention of Radio", Antenna, Volume 11 No. 2, May 1998, Society for the History of Technology
- Lauer, H., & Brown, H. L. (1919). Radio engineering principles. New York: McGraw-Hill book company; [etc., etc.]
- Rockman, H. B. (2004). Intellectual property law for engineers and scientists. New York [u.a.: IEEE Press].
- United States Court case
- "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.
- Books and articles
- listed by date, earliest first
- Telegraphing across space, Electric wave method. The Electrical engineer. (1884). London: Biggs & Co. (ed., the article is broke up, it begins on p. 466 and continues on p. 493.)
- Fahie, J. J. (1900). A history of wireless telegraphy, 1838-1899: including some bare-wire proposals for subaqueous telegraphs. Edinburgh: W. Blackwood and Sons.
- Thompson, S. P., Homans, J. E., & Tesla, N. (1903). Polyphase electric currents and alternate-current motors. "Wireless Telegraphy". The library of electrical science, v. 6. New York: P.F. Collier & Son.
- Sewall, C. H. (1904). Wireless telegraphy: its origins, development, inventions, and apparatus. New York: D. Van Nostrand.
- Trevert, E. (1904). The A.B.C. of wireless telegraphy; a plain treatise on Hertzian wave signaling; embracing theory, methods of operation, and how to build various pieces of the apparatus employed. Lynn, Mass: Bubier Pub.
- Collins, A. F. (1905). Wireless telegraphy; its history, theory and practice. New York: McGraw Pub.
- Mazzotto, D., & Bottone, S. R. (1906). Wireless telegraphy and telephony. London: Whittaker & Co.
- Erskine-Murray, J. (1907). A handbook of wireless telegraphy: Its theory and practice, for the use of electrical engineers, students, and operators. London: Crosby Lockwood and Son. (ed., also available in the Van Nostrand (1909) version).
- Murray, J. E. (1907). A handbook of wireless telegraphy. New York: D. Van Nostrand Co.; [etc.]
- Simmons, H. H. (1908). "Wireless telegraphy", Outlines of electrical engineering. London: Cassell and Co.
- Fleming, J. A. (1908). The principles of electric wave telegraphy. London: New York and Co.
- Twining, H. L. V., & Dubilier, W. (1909). Wireless telegraphy and high frequency electricity; a manual containing detailed information for the construction of transformers, wireless telegraph and high frequency apparatus, with chapters on their theory and operation. Los Angeles, Cal: The author.
- Bottone, S. R. (1910). Wireless telegraphy and Hertzian waves. London: Whittaker & Co.
- Bishop, L. W. (1911). The wireless operators' pocketbook of information and diagrams. Lynn, Mass: Bubier Pub. Co.; [etc., etc.].
- Massie, W. W., & Underhill, C. R. (1911). Wireless telegraphy and telephony popularly explained. New York: D. Van Nostrand.
- Ashley, C. G., & Hayward, C. B. (1912). Wireless telegraphy and wireless telephony: an understandable presentation of the science of wireless transmission of intelligence. Chicago: American School of Correspondence.
- Stanley, R. (1914). Text book on wireless telegraphy. London: Longmans, Green.
- Thompson, S. P. (1915). Elementary lessons in electricity and magnetism. New York: Macmillan
- Bucher, E. E. (1917). Practical wireless telegraphy: A complete text book for students of radio communication. New York: Wireless Press, Inc.
- American Institute of Electrical Engineers. (1919). Transactions of the American Institute of Electrical Engineers. New York: American Institute of Electrical Engineers. (ed., Contains Radio Telephony — By E. B. Craft and E. H. Colpitts (Illustrated). Page 305)
- Stanley, R. (1919). Text-book on wireless telegraphy. London: Longmans, Green.
- Chisholm, H. (1910). The encyclopædia britannica: A dictionary of arts, sciences, literature and general information. Cambridge, Eng: At the University press. "Telegraph", "Part II - Wireless Telegraphy".
- American Technical Society. (1914). Cyclopedia of applied electricity: A general reference work on direct-current generators and motors, storage batteries, electrochemistry, welding, electric wiring, meters, electric light transmission, alternating-current machinery, telegraphy, etc. Volume 7. Wireless Telegraphy and Telephony By C. G. Ashley Page 147. Chicago: American technical society.
- Colby, F. M., Williams, T., & Wade, H. T. (1922). "Wireless Telegraphy", The New international encyclopaedia. New York: Dodd, Mead and Co.
- "Wireless telegraphy", The Encyclopaedia Britannica. (1922). London: Encyclopædia Britannica.
- Gutenberg project
- The New Physics and Its Evolution. Chapter VII : A Chapter in the History of Science: Wireless telegraphy by Lucien Poincaré, eBook #15207, released February 28, 2005.
- Comparative Study of the Hertz, Marconi and Tesla Low-Frequency Wireless Systems
- Howeth, Captain H.S. History of Communications – Electronics in the United States Navy, published 1963, GPO, 657 pages. Free online public domain US government published book.
- Wunsch, A.D., "Misreading the Supreme Court,” Antenna, Volume 11 No. 1, November 1998, Society for the History of Technology
- Katz, Randy H., "Look Ma, No Wires": Marconi and the Invention of Radio". History of Communications Infrastructures* Timeline: First Thirty Years of Radio, 1895-1925.
- White, Thomas H. (November 1, 2012). "Nikola Tesla: The Guy Who DIDN'T "Invent Radio"".