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2430:. Since without the spark no current could flow in the primary circuit, this effectively uncoupled the secondary from the primary circuit, allowing the secondary resonant circuit and antenna to oscillate completely free of the primary circuit after that (until the next spark). This produced output power centered on a single frequency instead of two frequencies. It also eliminated most of the energy loss in the spark, producing very lightly damped, long "ringing" waves, with decrements of only 0.08 to 0.25 (a Q of 12-38) and consequently a very "pure", narrow bandwidth radio signal. Another advantage was the rapid quenching allowed the time between sparks to be reduced, allowing higher spark rates of around 1000 Hz to be used, which had a musical tone in the receiver which penetrated radio static better. The quenched gap transmitter was called the "singing spark" system.
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2525:: In the earlier rotary gaps, the motor was not synchronized with the frequency of the AC transformer, so the spark occurred at random times in the AC cycle of the voltage applied to the capacitor. The problem with this was the interval between the sparks was not constant. The voltage on the capacitor when a moving electrode approached the stationary electrode varied randomly between zero and the peak AC voltage. The exact time when the spark started varied depending on the gap length the spark could jump, which depended on the voltage. The resulting random phase variation of successive damped waves resulted in a signal that had a "hissing" or "rasping" sound in the receiver.
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3014:, slowly replaced the spark transmitter in high-power radiotelegraphy stations. However spark transmitters remained popular in two way communication stations because most continuous wave transmitters were not capable of a mode called "break in" or "listen in" operation. With a spark transmitter, when the telegraph key was up between Morse symbols the carrier wave was turned off and the receiver was turned on, so the operator could listen for an incoming message. This allowed the receiving station, or a third station, to interrupt or "break in" to an ongoing transmission. In contrast, these early CW transmitters had to operate continuously; the
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so that a round-the-clock radio watch could be kept. US President Taft and the public heard reports of chaos on the air the night of the disaster, with amateur stations interfering with official naval messages and passing false information. In response
Congress passed the 1912 Radio Act, in which licenses were required for all radio transmitters, maximum damping of transmitters was limited to a decrement of 0.2 to get old noisy non-syntonic transmitters off the air, and amateurs were mainly restricted to the unused frequencies above 1.5 MHz and output power of 1 kilowatt.
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until the stored energy is dissipated, permitting practical operation only up to around 60 signals per second. If active measures are taken to break the arc (either by blowing air through the spark or by lengthening the spark gap), a much shorter "quenched spark" may be obtained. A simple quenched spark system still permits several oscillations of the capacitor circuit in the time taken for the spark to be quenched. With the spark circuit broken, the transmission frequency is solely determined by the antenna resonant circuit, which permits simpler tuning.
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770:, the capacitor was charged by AC from a high-voltage transformer as above, and discharged by a spark gap consisting of electrodes spaced around a wheel which was spun by an electric motor, which produced sparks as they passed by a stationary electrode. The spark rate was equal to the rotations per second times the number of spark electrodes on the wheel. It could produce spark rates up to several thousand hertz, and the rate could be adjusted by changing the speed of the motor. The rotation of the wheel was usually synchronized to the AC
716:
contact, opening the switch and cutting off the primary current. Then the magnetic field collapses, creating a pulse of high voltage in the secondary winding, and the interrupter arm springs back to close the contact again, and the cycle repeats. Each pulse of high voltage charged up the capacitor until the spark gap fired, resulting in one spark per pulse. Interrupters were limited to low spark rates of 20–100 Hz, sounding like a low buzz in the receiver. In powerful induction coil transmitters, instead of a vibrating interrupter, a
2394:. The oscillating radio frequency energy was passed rapidly back and forth between the primary and secondary resonant circuits as long as the spark continued. Each time the energy returned to the primary, some was lost as heat in the spark. In addition, unless the coupling was very loose the oscillations caused the transmitter to transmit on two separate frequencies. Since the narrow passband of the receiver's resonant circuit could only be tuned to one of these frequencies, the power radiated at the other frequency was wasted.
1363:
2197:, which lost funding and was abandoned unfinished after Marconi's success). Marconi's original round 400-wire transmitting antenna collapsed in a storm 17 September 1901 and he hastily erected a temporary antenna consisting of 50 wires suspended in a fan shape from a cable between two 160 foot poles. The frequency used is not known precisely, as Marconi did not measure wavelength or frequency, but it was between 166 and 984 kHz, probably around 500 kHz. He received the signal on the coast of St. John's,
1746:(coil) between the sides of his dipole antennas, which resonated with the capacitance of the antenna to make a tuned circuit. Although his complicated circuit did not see much practical use, Lodge's "syntonic" patent was important because it was the first to propose a radio transmitter and receiver containing resonant circuits which were tuned to resonance with each other. In 1911 when the patent was renewed the Marconi Company was forced to buy it to protect its own syntonic system against infringement suits.
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737:, when the capacitor was fully charged. Since the AC sine wave has two peaks per cycle, ideally two sparks occurred during each cycle, so the spark rate was equal to twice the frequency of the AC power (often multiple sparks occurred during the peak of each half cycle). The spark rate of transmitters powered by 50 or 60 Hz mains power was thus 100 or 120 Hz. However higher audio frequencies cut through interference better, so in many transmitters the transformer was powered by a
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of the above prior patents, Marconi in his 26 April 1900 "four circuit" or "master tuning" patent on his system claimed rights to the inductively coupled transmitter and receiver. This was granted a
British patent, but the US patent office twice rejected his patent as lacking originality. Then in a 1904 appeal a new patent commissioner reversed the decision and granted the patent, on the narrow grounds that Marconi's patent by including an antenna
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2794:. In the US prior to 1912 there was no government regulation of radio, and a chaotic "wild west" atmosphere prevailed, with stations transmitting without regard to other stations on their frequency, and deliberately interfering with each other. The expanding numbers of non-syntonic broadband spark transmitters created uncontrolled congestion in the airwaves, interfering with commercial and military wireless stations.
2639:, one of the most powerful spark transmitters ever built. During World War I it transmitted telegram traffic at 200 words per minute on 21.5 kHz to receivers in Belmar, New Jersey. The roar of the spark could reportedly be heard a kilometer away. On 22 September 1918 it transmitted the first wireless message from Britain to Australia, a distance of 15,200 km (9,439 miles). In 1921 it was replaced by
1149:, and largely failed to foresee its possibilities as a communication technology. Due to the influence of Maxwell's theory, their thinking was dominated by the similarity between radio waves and light waves; they thought of radio waves as an invisible form of light. By analogy with light, they assumed that radio waves only traveled in straight lines, so they thought radio transmission was limited by the visual
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677:. As long as the key is pressed the spark gap fires repetitively, creating a string of pulses of radio waves, so in a receiver the keypress sounds like a buzz; the entire Morse code message sounds like a sequence of buzzes separated by pauses. In low-power transmitters the key directly breaks the primary circuit of the supply transformer, while in high-power transmitters the key operates a heavy duty
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equipment that was still being used on older ships. The
Convention prohibited licensing of new land spark transmitters after 1929. Damped wave radio emission, called Class B, was banned after 1934 except for emergency use on ships. This loophole allowed shipowners to avoid replacing spark transmitters, which were kept as emergency backup transmitters on ships through World War II.
1762:. The energy in each spark, and thus the power output, was no longer limited by the capacitance of the antenna but by the size of the capacitor in the resonant circuit. In order to increase the power very large capacitor banks were used. The form that the resonant circuit took in practical transmitters was the inductively-coupled circuit described in the next section.
1604:). During each spark the energy stored in the antenna was quickly radiated away as radio waves, so the oscillations decayed to zero quickly. The radio signal consisted of brief pulses of radio waves, repeating tens or at most a few hundreds of times per second, separated by comparatively long intervals of no output. The power radiated was dependent on how much
988:
4371:, Applied: 2 June 1896, full specification: 2 March 1897, accepted: 2 July 1897. British patents allowed the full specification to be submitted after the application. Marconi's monopole antenna did not appear in his initial June 1896 application but in his March 1897 specification. Corresponding US patent 586193, Marconi, Guglielmo,
2143:. This would require a major scale-up in power, a risky gamble for his company. Up to that time his small induction coil transmitters had an input power of 100 - 200 watts, and the maximum range achieved was around 150 miles. To build the first high power transmitter, Marconi hired an expert in electric power engineering, Prof.
1796:
4920:"Crookes’s article was read very widely—and more than that, attended to and remembered—both in Europe and in the United States; there is hardly one figure important in the early days of radio who does not at some point in his memoirs or correspondence refer to the article of 1892 as having made a difference."
1809:
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George
Fitzgerald as early as 1892 described a spark oscillator as similar to the oscillations produced when a cork pops out of a winebottle, and said what was needed was a continuous electromagnetic "whistle". He realized that if the resistance of a tuned circuit were made zero or negative it would
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s call as its radio operator had gone to bed. This was held responsible for most of the 1500 deaths. Existing international regulations required all ships with more than 50 passengers to carry wireless equipment, but after the disaster subsequent regulations mandated ships have enough radio officers
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gap. A quenched gap consisted of a stack of wide cylindrical electrodes separated by thin insulating spacer rings to create many narrow spark gaps in series, of around 0.1–0.3 mm (0.004–0.01 in). The wide surface area of the electrodes terminated the ionization in the gap quickly by cooling
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Marconi at first paid little attention to syntony, but by 1900 developed a radio system incorporating features from these systems, with a two circuit transmitter and two circuit receiver, with all four circuits tuned to the same frequency, using a resonant transformer he called the "jigger". In spite
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used also had no resonant circuits, so they had no way of selecting one signal from others besides the broad resonance of the antenna, and responded to the transmissions of all transmitters in the vicinity. An example of this interference problem was an embarrassing public debacle in August 1901 when
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of the transmitter, which is the number of sinusoidal oscillations per second in each damped wave. Since the transmitter produces one pulse of radio waves per spark, the output power of the transmitter was proportional to the spark rate, so higher rates were favored. Spark transmitters generally used
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to zero. When the oscillating electric current in the primary circuit has decreased to a point where it is insufficient to keep the air in the spark gap ionized, the spark stops, opening the resonant circuit, and stopping the oscillations. In a transmitter with two resonant circuits, the oscillations
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for deep body heating. High oscillating voltages of hundreds of thousands of volts at frequencies of 0.1 - 1 MHz from a Tesla coil were applied directly to the patient's body. The treatment was not painful, because currents in the radio frequency range do not cause the physiological reaction of
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Knowledgeable sources today doubt whether
Marconi actually received this transmission. Ionospheric conditions should not have allowed the signal to be received during the daytime at that range. Marconi knew the Morse code signal to be transmitted was the letter 'S' (three dots). He and his assistant
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provided the means for tuning the four circuits to the same frequency, whereas in the Tesla and Stone patents this was done by adjusting the length of the antenna. This patent gave
Marconi a near monopoly of syntonic wireless telegraphy in England and America. Tesla sued Marconi's company for patent
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of the circuit so the oscillations were less damped. Another advantage was the frequency of the transmitter was no longer determined by the length of the antenna but by the resonant circuit, so it could easily be changed by adjustable taps on the coil. The antenna was brought into resonance with the
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The transmitter works in a rapid repeating cycle in which the capacitor is charged to a high voltage by the transformer and discharged through the coil by a spark across the spark gap. The impulsive spark excites the resonant circuit to "ring" like a bell, producing a brief oscillating current which
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in synchronism with the cycles of the AC voltage to the transformer, so the spark occurred at the same points of the voltage sine wave each cycle. Usually it was designed so there was one spark each half cycle, adjusted so the spark occurred at the peak voltage when the capacitor was fully charged.
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Marconi's achievement received worldwide publicity, and was the final proof that radio was a practical communication technology. The scientific community at first doubted
Marconi's report. Virtually all wireless experts besides Marconi believed that radio waves traveled in straight lines, so no one
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The inductively coupled or "syntonic" spark transmitter was the first type that could communicate at intercontinental distances, and also the first that had sufficiently narrow bandwidth that interference between transmitters was reduced to a tolerable level. It became the dominant type used during
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so the moving electrode passed by the stationary one at the peak of the sine wave, initiating the spark when the capacitor was fully charged, which produced a musical tone in the receiver. When tuned correctly in this manner, the need for external cooling or quenching airflow was eliminated, as was
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steps the input voltage up to the high voltage needed. The sinusoidal voltage from the transformer is applied directly to the capacitor, so the voltage on the capacitor varies from a high positive voltage, to zero, to a high negative voltage. The spark gap is adjusted so sparks only occur near the
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audiences and aviation authorities were complaining of the disruption to radio reception that noisy legacy marine spark transmitters were causing. But shipping interests vigorously fought a blanket prohibition on damped waves, due to the capital expenditure that would be required to replace spark
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can only have low damping (high Q, narrow bandwidth) if it is a "closed" circuit, with no energy dissipating components. But such a circuit does not produce radio waves. A resonant circuit with an antenna radiating radio waves (an "open" tuned circuit) loses energy quickly, giving it high damping
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The speed at which signals may be transmitted is naturally limited by the time taken for the spark to be extinguished. If, as described above, the conductive plasma does not, during the zero points of the alternating current, cool enough to extinguish the spark, a 'persistent spark' is maintained
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waves (CW), had theoretical advantages over damped waves for radio transmission. Because their energy is essentially concentrated at a single frequency, in addition to causing almost no interference to other transmitters on adjacent frequencies, continuous wave transmitters could transmit longer
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and reinforced each other. The result was essentially a continuous sinusoidal wave, whose amplitude varied with a ripple at the spark rate. This system was necessary to give
Marconi's transoceanic stations a narrow enough bandwidth that they didn't interfere with other transmitters on the narrow
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repeatedly breaks the circuit that provides current to the primary winding, causing the coil to generate pulses of high voltage. When the primary current to the coil is turned on, the primary winding creates a magnetic field in the iron core which pulls the springy interrupter arm away from its
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This troublesome backflow of energy to the primary circuit could be prevented by extinguishing (quenching) the spark at the right instant, after all the energy from the capacitors was transferred to the antenna circuit. Inventors tried various methods to accomplish this, such as air blasts and
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were developed, which were less expensive and produced continuous waves which had a greater range, produced less interference, and could also carry audio, making spark transmitters obsolete by 1920. The radio signals produced by spark-gap transmitters are electrically "noisy"; they have a wide
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and others. It consisted of multiple electrodes equally spaced around a disk rotor spun at high speed by a motor, which created sparks as they passed by a stationary electrode. By using the correct motor speed, the rapidly separating electrodes extinguished the spark after the energy had been
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of the radiated signal, it would occupy a smaller range of frequencies around its center frequency, so that the signals of transmitters "tuned" to transmit on different frequencies would no longer overlap. A receiver which had its own resonant circuit could receive a particular transmitter by
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of the coil when the capacitor voltage reaches zero the current doesn't stop but keeps flowing, charging the capacitor plates with an opposite polarity, until the charge is stored in the capacitor again, on the opposite plates. Then the process repeats, with the charge flowing in the opposite
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to carry sound. The problem was no techniques were known for generating them. The efforts described above to reduce the damping of spark transmitters can be seen as attempts to make their output approach closer to the ideal of a continuous wave, but spark transmitters could not produce true
1916:. The advantage of the inductively coupled circuit was that the "loosely coupled" transformer transferred the oscillating energy of the tank circuit to the radiating antenna circuit gradually, creating long "ringing" waves. A second advantage was that it allowed a large primary capacitance
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The cycle begins when current from the transformer charges up the capacitor, storing positive electric charge on one of its plates and negative charge on the other. While the capacitor is charging the spark gap is in its nonconductive state, preventing the charge from escaping through the
857:". Maxwell proposed that light consisted of electromagnetic waves of short wavelength, but no one knew how to confirm this, or generate or detect electromagnetic waves of other wavelengths. By 1883 it was theorized that accelerated electric charges could produce electromagnetic waves, and
2507:
216:
Pictorial diagram of a simple spark-gap transmitter from a 1917 boy's hobby book, showing examples of the early electronic components used. It is typical of the low-power transmitters homebuilt by thousands of amateurs during this period to explore the exciting new technology of
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1957:) attached to an elevated wire monopole antenna transmitted radio waves, which were received across the room by a similar wire antenna attached to a receiver consisting of a second grounded resonant transformer tuned to the transmitter's frequency, which lighted a
2260:("static") in their earphones for the clicks of the transmitter. Marconi made many subsequent transatlantic transmissions which clearly establish his priority, but reliable transatlantic communication was not achieved until 1907 with more powerful transmitters.
1293:, mainly by combining and tinkering with the inventions of others. Starting at age 21 on his family's estate in Italy, between 1894 and 1901 he conducted a long series of experiments to increase the transmission range of Hertz's spark oscillators and receivers.
1403:. The length of the antenna determined the wavelength of the waves produced and thus their frequency. Longer, lower frequency waves have less attenuation with distance. As Marconi tried longer antennas, which radiated lower frequency waves, probably in the
865:. Fitzgerald in a brief note published in 1883 suggested that electromagnetic waves could be generated practically by discharging a capacitor rapidly; the method used in spark transmitters, however there is no indication that this inspired other inventors.
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gas, eroded the spark electrodes, and could be a fire hazard. Despite its drawbacks, most wireless experts believed along with
Marconi that the impulsive "whipcrack" of a spark was necessary to produce radio waves that would communicate long distances.
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The first application of radio was on ships, to keep in touch with shore, and send out a distress call if the ship were sinking. The
Marconi Company built a string of shore stations and in 1904 established the first Morse code distress call, the letters
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to carry sound. Due to the development of the first high-power transmitting tubes by the end of World War I, in the 1920s tube transmitters replaced the arc converter and alternator transmitters, as well as the last of the old noisy spark transmitters.
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and capacitor in the primary circuit of the induction coil produced a continuous string of damped waves. Hertz often just used a pushbutton switch, which created a single spark and pulse of radio waves when pushed, resulting in a single spark in his
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the "spark" era. A drawback of the plain inductively coupled transmitter was that unless the primary and secondary coils were very loosely coupled it radiated on two frequencies. This was remedied by the quenched-spark and rotary gap transmitters
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The energy in the resonant circuit is limited to the amount of energy originally stored in the capacitor. The radiated radio waves, along with the heat generated by the spark, uses up this energy, causing the oscillations to decrease quickly in
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The largest spark transmitters were powerful transoceanic radiotelegraphy stations with input power of 100 - 300 kW. Beginning about 1910, industrial countries built global networks of these stations to exchange commercial and diplomatic
1961:. This system, patented by Tesla 2 September 1897, 4 months after Lodge's "syntonic" patent, was in effect an inductively coupled radio transmitter and receiver, the first use of the "four circuit" system claimed by Marconi in his 1900 patent
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He was unable to communicate beyond a half-mile until 1895, when he discovered that the range of transmission could be increased greatly by replacing one side of the Hertzian dipole antenna in his transmitter and receiver with a connection to
1593:(also called LC circuits, tank circuits, or tuned circuits), the spark gap was in the antenna, which functioned as the resonator to determine the frequency of the radio waves. These were called "unsyntonized" or "plain antenna" transmitters.
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attempted to report the New York Yacht Race to newspapers from ships with their untuned spark transmitters. The Morse code transmissions interfered, and the reporters on shore failed to receive any information from the garbled signals.
2569:. These were discharged sequentially by multiple rotary discharger wheels on the same shaft to create overlapping damped waves shifted progressively in time, which were added together in the oscillation transformer so the output was a
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produce continuous oscillations, and tried to make an electronic oscillator by exciting a tuned circuit with negative resistance from a dynamo, what would today be called a parametric oscillator, but was unsuccessful. G. Fitzgerald,
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sinking 14 April 1912 increased public appreciation for the role of radio, but the loss of life brought attention to the disorganized state of the new radio industry, and prompted regulation which corrected some abuses. Although the
5024:(1) the idea of inductive coupling between the driving and the working circuits (2) the importance of tuning both circuits, i.e. the idea of an 'oscillation transformer' (3) the idea of a capacitance loaded open secondary circuit
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funded his experiments. Marconi applied for a patent on his radio system 2 June 1896, often considered the first wireless patent. In May 1897 he transmitted 14 km (8.7 miles), on 27 March 1899 he transmitted across the
1011:
2782:", many of them teenage boys, who used their homebuilt sets recreationally to contact distant amateurs and chat with them by Morse code, and relay messages. Low-power amateur transmitters ("squeak boxes") were often built with "
1620:" antennas characteristic of the "spark" era. The only other way to increase the energy stored in the antenna was to charge it up to very high voltages. However the voltage that could be used was limited to about 100 kV by
976:
711:(Ruhmkorff coil) was used in low-power transmitters, usually less than 500 watts, often battery-powered. An induction coil is a type of transformer powered by DC, in which a vibrating arm switch contact on the coil called an
312:. The advantage of this circuit was that the oscillating current persisted in the antenna circuit even after the spark stopped, creating long, ringing, lightly damped waves, in which the energy was concentrated in a narrower
1080:
were applied between the two sides of the antenna. Each pulse stored electric charge in the capacitance of the antenna, which was immediately discharged by a spark across the spark gap. The spark excited brief oscillating
1259:, limiting their power output. Therefore, these devices were not capable of long distance transmission; their reception range with the primitive receivers employed was typically limited to roughly 100 yards (100 meters).
817:
had come close to discovering radio in 1875; he had generated and detected radio waves which he called "etheric currents" experimenting with high-voltage spark circuits, but due to lack of time did not pursue the matter.
112:
around 1896. One of the first uses for spark-gap transmitters was on ships, to communicate with shore and broadcast a distress call if the ship was sinking. They played a crucial role in maritime rescues such as the 1912
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The inductively-coupled transmitter had a more complicated output waveform than the non-syntonic transmitter, due to the interaction of the two resonant circuits. The two magnetically coupled tuned circuits acted as a
308:. The antenna and ground were connected to the secondary winding. The capacitance of the antenna resonated with the secondary winding to make a second resonant circuit. The two resonant circuits were tuned to the same
800:
signals without wires. Experiments by a number of inventors had shown that electrical disturbances could be transmitted short distances through the air. However most of these systems worked not by radio waves but by
3893:. The text in full: "This is by utilizing the alternating currents produced when an accumulator is discharged through a small resistance. It would be possible to produce waves of ten meters wavelength, or even less"
388:
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of 15 or greater). Virtually the only spark transmitters which could satisfy this condition were the quenched-spark and rotary gap types above, and they dominated wireless telegraphy for the rest of the spark era.
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It became clear that for multiple transmitters to operate, some system of "selective signaling" had to be devised to allow a receiver to select which transmitter's signal to receive, and reject the others. In 1892
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of damped waves. The speed of the discharger wheel was controlled so that the time between sparks was equal to an integer multiple of the wave period. Therefore, oscillations of the successive wave trains were
1097:, which radiated waves roughly twice the length of the antenna (for example a dipole 1 meter long would generate 150 MHz radio waves). Hertz detected the waves by observing tiny sparks in micrometer spark gaps
1928:. The receiver in most systems also used two inductively coupled circuits, with the antenna an "open" resonant circuit coupled through an oscillation transformer to a "closed" resonant circuit containing the
1525:
communication at increasingly long distances convinced the world that radio, or "wireless telegraphy" as it was called, was not just a scientific curiosity but a commercially useful communication technology.
693:
of the transmitter, the number of sparks and resulting damped wave pulses it produces per second, which determines the tone of the signal heard in the receiver. The spark rate should not be confused with the
5971:
3131:
toy trucks, boats and robots called Radicon, which used a low-power spark transmitter in the controller as an inexpensive way to produce the radio control signals. The signals were received in the toy by a
619:
1802:
Standard Marconi inductively coupled transmitter on ship 1902. Spark gap is in front of induction coil, lower right. The spiral oscillation transformer is in the wooden box on the wall above the Leyden
2951:
Beginning about 1904, continuous wave transmitters were developed using new principles, which competed with spark transmitters. Continuous waves were first generated by two short-lived technologies:
2014:
830:. Neither of these individuals are usually credited with the discovery of radio, because they did not understand the significance of their observations and did not publish their work before Hertz.
3318:
Individual nations enforce this prohibition in their communication laws. In the United States, Federal Communications Commission (FCC) regulations make it a felony to operate a spark transmitter:
2283:
2778:
used to receive them were simple enough that they were widely built by hobbyists. During the first decades of the 20th century this exciting new high tech hobby attracted a growing community of "
1521:, 46 km (28 miles), in fall 1899 he extended the range to 136 km (85 miles), and by January 1901 he had reached 315 km (196 miles). These demonstrations of wireless
1236:
of radio waves. He also measured the speed of radio waves, showing they traveled at the same speed as light. These experiments established that light and radio waves were both forms of Maxwell's
389:
921:
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is radiated as electromagnetic waves by the antenna. The transmitter repeats this cycle at a rapid rate, so the spark appeared continuous, and the radio signal sounded like a whine or buzz in a
209:; the charge flows rapidly back and forth through the spark gap for a brief period, charging the conductors on each side alternately positive and negative, until the oscillations die away.
1157:, and therefore was not capable of longer distance communication. As late as 1894 Oliver Lodge speculated that the maximum distance Hertzian waves could be transmitted was a half mile.
2513:
US Navy 100 kW rotary gap transmitter built by Fessenden in 1913 at Arlington, Virginia. It transmitted on 113 kHz to Europe, and broadcast the US's first radio time signal.
2501:'s 35 kW synchronous rotary spark transmitter, built 1905 at Brant Rock, Massachusetts, with which he achieved the first 2 way transatlantic communication in 1906 on 88 kHz.
2883:
Co. which was dominant outside the British Empire. Marconi transmitters used the timed spark rotary discharger, while Telefunken transmitters used its quenched spark gap technology.
279:. However, this meant that the electromagnetic energy produced by the transmitter was dissipated across a wide band, thereby limiting its effective range to a few kilometers at most.
237:
to 75-100 kilovolts in powerful transmitters) to jump across the spark gap. The transformer charges the capacitor. In low-power transmitters powered by batteries this was usually an
2070:
invalidated the inductive coupling claims of Marconi's patent due to the prior patents of Lodge, Tesla, and Stone, but this came long after spark transmitters had become obsolete.
6352:
4191:
3075:
The 1927 International Radiotelegraph Convention in Washington, D.C. saw a political battle to finally eliminate spark radio. Spark transmitters were obsolete at this point, and
2046:
1841:(low Q, wide bandwidth). There was a fundamental tradeoff between a circuit which produced persistent oscillations which had narrow bandwidth, and one which radiated high power.
1723:
to the frequency of the desired transmitter, analogously to the way one musical instrument could be tuned to resonance with another. This is the system used in all modern radio.
469:
in the secondary circuit and antenna may continue some time after the spark has terminated. Then the transformer begins charging the capacitor again, and the whole cycle repeats.
1655:, which made it impossible for other transmitters to be heard. When multiple transmitters attempted to operate in the same area, their broad signals overlapped in frequency and
1427:
propagation. Marconi did not understand any of this at the time; he simply found empirically that the higher his vertical antenna was suspended, the further it would transmit.
2544:
To reduce interference caused by the "noisy" signals of the burgeoning numbers of spark transmitters, the 1912 US Congress "Act to Regulate Radio Communication" required that "
445:
direction through the coil. This continues, resulting in oscillating currents flowing rapidly back and forth between the plates of the capacitor through the coil and spark gap.
2561:
In 1912 in his high-power stations Marconi developed a refinement of the rotary discharger called the "timed spark" system, which generated what was probably the nearest to a
1030:
Hertz's first oscillator: a pair of one meter copper wires with a 7.5 mm spark gap between them, ending in 30 cm zinc spheres. When 20,000 volt pulses from an induction coil
906:
1105:
was also experimenting with spark oscillators at this time and came close to discovering radio waves before Hertz, but his focus was on waves on wires, not in free space.
448:
The resonant circuit is connected to the antenna, so these oscillating currents also flow in the antenna, charging and discharging it. The current creates an oscillating
183:
between two conductors was the first device known which could generate radio waves. The spark itself doesn't produce the radio waves, it merely serves as a fast acting
2309:
Quenched spark gap from transmitter, left. The handle turns a screw which puts pressure on the stack of cylindrical electrodes, allowing the gap widths to be adjusted.
2863:, radio became a strategic defensive technology, as it was realized a nation without long distance radiotelegraph stations could be isolated by an enemy cutting its
4571:
892:, which were called "Hertzian waves" until about 1910. Hertz was inspired to try spark excited circuits by experiments with "Reiss spirals", a pair of flat spiral
3915:
Translated from German by A. E. Selig. Zenneck describes the Marconi, Braun, and Wien transmitters on p. 173, and the early "lineal" or Hertz oscillators on p. 41.
1768:
381:
2174:, which generated the output. The spark rate was low, perhaps as low as 2 - 3 sparks per second. Fleming estimated the radiated power was around 10 - 12 kW.
1612:
of the antenna. To increase their capacitance to ground, antennas were made with multiple parallel wires, often with capacitive toploads, in the "harp", "cage", "
1255:
The high frequencies produced by Hertzian oscillators could not travel beyond the horizon. The dipole resonators also had low capacitance and couldn't store much
2271:
560:
537:
510:
2583:
band. Timed spark transmitters achieved the longest transmission range of any spark transmitters, but these behemoths represented the end of spark technology.
6772:
2887:
were used to transmit Morse code text at high speed. To achieve a maximum range of around 3000 – 6000 miles, transoceanic stations transmitted mainly in the
300:
of the transformer made one resonant circuit, which generated the oscillating current. The oscillating current in the primary winding created an oscillating
2228:(including Marconi) understood how the waves had managed to propagate around the 300 mile high curve of the Earth between Britain and Newfoundland. In 1902
7224:
4677:
2540:
with the line frequency. The synchronous gap was said to produce a more musical, easily heard tone in the receiver, which cut through interference better.
868:
The division of the history of spark transmitters into the different types below follows the organization of the subject used in many wireless textbooks.
1419:
that followed the contour of the Earth. Under certain conditions they could also reach beyond the horizon by reflecting off layers of charged particles (
3022:
could not operate as long as the transmitter was powered up. Therefore, these stations could not receive messages until the transmitter was turned off.
2923:, which due to their large bandwidth caused interference between transmitters. The spark also made a very loud noise when operating, produced corrosive
1282:
was one of the first people to believe that radio waves could be used for long distance communication, and singlehandedly developed the first practical
813:
claimed to have transmitted an electrical signal through the atmosphere between two 600 foot wires held aloft by kites on mountaintops 14 miles apart.
1541:
throughout the spark era. Inspired by Marconi, in the late 1890s other researchers also began developing competing spark radio communication systems;
6586:
5451:
1415:
waves produced by Hertz's horizontal antennas. These longer vertically polarized waves could travel beyond the horizon, because they propagated as a
2480:
2445:
A second type of spark gap that had a similar quenching effect was the "rotary gap", invented by Tesla in 1896 and applied to radio transmitters by
2422:
it after the current stopped. In the inductively coupled transmitter, the narrow gaps extinguished ("quenched") the spark at the first nodal point (
6571:
3367:
336:, a metal conductor such as an elevated wire, that radiates the power in the oscillating electric currents from the resonant circuit into space as
3397:
1212:
bands. In his various experiments, Hertz produced waves with frequencies from 50 to 450 MHz, roughly the frequencies used today by broadcast
1068:
a common lab power source which produced pulses of high voltage, 5 to 30 kV. In addition to radiating the waves, the antenna also acted as a
4994:
673:
in the primary circuit of the transformer, producing sequences of short (dot) and long (dash) strings of damped waves, to spell out messages in
3805:
1742:, who had been researching electrical resonance for years, patented the first "syntonic" transmitter and receiver in May 1897 Lodge added an
3573:
70:
built the first experimental spark-gap transmitters in 1887, with which he proved the existence of radio waves and studied their properties.
3424:
7932:
7904:
7899:
6924:
5626:. Proceedings of the 1995 International Conference on 100 Years of Radio. London: Institute of Engineering and Technology. pp. 32–34.
1681:
4159:
Signor Marconi's Magic Box: The Most Remarkable Invention Of The 19th Century & The Amateur Inventor Whose Genius Sparked A Revolution
3120:
discovered that RF currents applied to a scalpel could cut and cauterize tissue in medical operations, and spark oscillators were used as
2619:
2456:
473:
The cycle is very rapid, taking less than a millisecond. With each spark, this cycle produces a radio signal consisting of an oscillating
6557:
4822:
3208:
5933:
2147:
of University College, London, who applied power engineering principles. Fleming designed a complicated inductively-coupled transmitter
1920:
to be used which could store a lot of energy, increasing the power output enormously. Powerful transoceanic transmitters often had huge
4856:
4514:
4487:
3099:
The spark gap oscillator was also used in nonradio applications, continuing long after it became obsolete in radio. In the form of the
720:
was used. This could break the current at rates up to several thousand hertz, and the rate could be adjusted to produce the best tone.
1501:
French non-syntonic transmitter used for ship-to-shore communication around 1900. It had a range of about 10 kilometres (6.2 mi).
624:
The transmitter repeats this cycle rapidly, so the output is a repeating string of damped waves. This is equivalent to a radio signal
4554:
2139:
Marconi decided in 1900 to attempt transatlantic communication, which would allow him to dominate Atlantic shipping and compete with
6876:
5972:
Improvements relating to the production, regulation, and utilization of electric currents of high frequency, and apparatus therefore
1836:
In developing these syntonic transmitters, researchers found it impossible to achieve low damping with a single resonant circuit. A
1268:
I could scarcely conceive it possible that application to useful purposes could have escaped the notice of such eminent scientists.
2131:
1533:. and radio communication began to be used commercially around 1900. His first large contract in 1901 was with the insurance firm
568:
133:(RFI) that can disrupt other radio transmissions. This type of radio emission has been prohibited by international law since 1934.
4938:
4876:
Wireless telegraphy and wireless telephony: An understandable presentation of the science of wireless transmission of intelligence
4716:
Wireless Telegraphy and Wireless Telephony: An understandable presentation of the science of wireless transmission of intelligence
275:
The earliest spark-gap transmitters before 1897 did not have a resonant circuit; the antenna performed this function, acting as a
73:
A fundamental limitation of spark-gap transmitters is that they generate a series of brief transient pulses of radio waves called
5422:
7926:
5781:
2907:
antennas up to several miles long with large capacitive toploads, to achieve adequate efficiency. The antenna required a large
2104:
Marconi's transmitting station at Poldhu, Cornwall, showing the original 400-wire vertical inverted cone aerial which collapsed
2665:
was agreed on. The first significant marine rescue due to radiotelegraphy was the 23 January 1909 sinking of the luxury liner
2098:
7921:
7911:
7891:
7693:
6104:
6054:
5319:
3320:
3235:
2603:
1407:
band around 2 MHz, he found that he could transmit further. Another advantage was that these vertical antennas radiated
17:
2468:
2345:
A powerful quenched-spark transmitter in Australia. The 6 cylinders in front of the Leyden jars are the quenched spark gaps.
1624:
which caused charge to leak off the antenna, particularly in wet weather, and also energy lost as heat in the longer spark.
880:
in 1887 built the first experimental spark gap transmitters during his historic experiments to demonstrate the existence of
8004:
6864:
5865:
7058:
4036:
198:
in the conductors of the attached circuit. The conductors radiate the energy in this oscillating current as radio waves.
7983:
7916:
7762:
6739:
5624:
Fessenden and Marconi: Their differing technologies and transatlantic experiments during the first decade of this century
3262:
1932:. A radio system with a "two circuit" (inductively coupled) transmitter and receiver was called a "four circuit" system.
665:
In order to transmit information with this signal, the operator turns the transmitter on and off rapidly by tapping on a
6897:
6382:
4539:
3292:
2565:
that sparks could produce. He used several identical resonant circuits in parallel, with the capacitors charged by a DC
2450:
transferred to the secondary. The rotating wheel also kept the electrodes cooler, important in high-power transmitters.
1726:
During the period 1897 to 1900 wireless researchers realized the advantages of "syntonic" or "tuned" systems, and added
1340:
Marconi's first monopole antenna transmitter, 1895. One side of spark gap grounded, the other attached to a metal plate
8019:
7688:
6623:
6528:
5895:
5841:
5814:
5561:
5432:
5292:
5201:
5171:
5131:
5104:
4634:. Proceedings of the 1995 International Conference on 100 Years of Radio. London: Institute of Engineering Technology.
4581:
4524:
4497:
4461:
4429:
4345:
4318:
4201:
4167:
4140:
4078:
4046:
3864:
3815:
3785:
3468:
3434:
3407:
3377:
3245:
3218:
2838:
2426:) when the primary current momentarily went to zero after all the energy had been transferred to the secondary winding
4921:
2123:
7782:
4647:
4108:
4016:
717:
5719:
5309:
4785:
1943:
in 1891. At a March 1893 St. Louis lecture he had demonstrated a wireless system that, although it was intended for
1860:
The solution found by a number of researchers was to use two resonant circuits in the transmitter, with their coils
1596:
The average power output of these transmitters was low, because due to its low capacitance the antenna was a highly
1085:
of current between the sides of the antenna. The antenna radiated the energy as a momentary pulse of radio waves; a
7567:
7115:
6917:
6712:
2920:
2546:
the logarithmic decrement per oscillation in the wave trains emitted by the transmitter shall not exceed two tenths
1086:
486:
74:
6776:
2591:
982:
Hertz's 450 MHz transmitter; a 26 cm dipole with spark gap at focus of a sheet metal parabolic reflector
7678:
4419:
4335:
4068:
1233:
6678:
3139:
Spark gap oscillators are still used to generate high-frequency high voltage needed to initiate welding arcs in
2891:(VLF) band, from 50 kHz to as low as 15 – 20 kHz. At these wavelengths even the largest antennas were
2110:
1380:
Later researchers found that multiple parallel wires were a better way to increase capacitance. "Cage antennas"
7673:
2127:
Circuit of Poldhu transmitter. Fleming's curious dual spark gap design was not used in subsequent transmitters.
93:
radio transmission. So spark-gap transmitters could not transmit audio, and instead transmitted information by
3879:
Fitzgerald, George "On a method of producing electromagnetic disturbances of comparatively short wavelength",
3350:
7698:
6326:
5831:
5804:
2868:
1947:, had many of the elements of later radio communication systems. A grounded capacitance-loaded spark-excited
1738:(coils of wire) to transmitters and receivers, to make resonant circuits (tuned circuits, or tank circuits).
1715:
1640:
1530:
313:
126:
108:
The first practical spark gap transmitters and receivers for radiotelegraphy communication were developed by
6859:
4661:
4451:
7973:
7734:
7631:
7174:
6969:
6941:
2245:
1656:
130:
5493:
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4603:
3673:
1396:
and the other side with a long wire antenna suspended high above the ground. These antennas functioned as
749:, that produced AC at a higher frequency, usually 500 Hz, resulting in a spark rate of 1000 Hz.
58:. Spark-gap transmitters were the first type of radio transmitter, and were the main type used during the
7963:
7470:
6910:
6661:
5672:
5191:
5121:
4225:
Electric Waves: Being Researches on the Propagation of Electric Action with Finite Velocity Through Space
3936:
Electric Waves: Being Researches on the Propagation of Electric Action with Finite Velocity Through Space
2369:
1944:
1542:
282:
Most spark transmitters had two resonant circuits coupled together with an air core transformer called a
205:
of circuit conductors, the discharge of a capacitor through a low enough resistance (such as a spark) is
6088:
5454:, filed: 26 April 1900, granted: 13 April 1901. Corresponding US Patent no. 763,772, Guglielmo Marconi,
3092:
were regularly nicknamed "Sparky" long after the devices ceased to be used. Even today, the German verb
2437:
Co., Marconi's rival, acquired the patent rights and used the quenched spark gap in their transmitters.
8009:
7822:
7744:
7683:
7390:
3854:
2820:
which rescued 705 survivors, the rescue operation was delayed four hours because the nearest ship, the
2221:
1988:
in February 1900. Braun made the crucial discovery that low damping required "loose coupling" (reduced
1669:
6417:
6037:
5591:
233:
electricity from the power source, a battery or electric outlet, to a high enough voltage (from a few
7594:
7555:
7400:
7300:
7229:
7162:
6989:
6005:
2867:. Most of these networks were built by the two giant wireless corporations of the age: the British
2864:
2843:
2140:
1816:
1130:
858:
827:
806:
5632:
2212:. Marconi announced the first transatlantic radio transmission took place on 12 December 1901, from
1900:) formed a "closed" resonant circuit which generated the oscillations, while the secondary winding (
1844:
775:
the loss of power directly from the charging circuit (parallel to the capacitor) through the spark.
7953:
7195:
7130:
7083:
7043:
3140:
2597:
Transmitter building, showing the 36 feedlines feeding power to the 3,600 ft. flattop wire antenna.
2198:
6198:
5076:
4904:
4772:
4229:
3775:
3609:
2536:
Thus the spark had a steady frequency equal to a multiple of the AC line frequency, which created
947:
Hertzian spark oscillator, 1902. Visible are antenna consisting of 2 wires ending in metal plates
7792:
7777:
7621:
7572:
7495:
7395:
7073:
6959:
6954:
6646:
5913:
5702:
4880:
4098:
3940:
3910:
3543:
2983:
2872:
2640:
2570:
1786:
Amateur inductively coupled spark transmitter and receiver, 1910. The spark gap is in glass bulb
1631:
Emission bandwidth of a spark gap transmitter showing signal strength versus wavelength in meters
1412:
1324:
Marconi first tried enlarging the dipole antenna with 6×6 foot metal sheet "capacity areas"
802:
372:
5986:
4974:
3030:
3018:
was not turned off between Morse code symbols, words, or sentences but just detuned, so a local
1469:
during a demonstration 1897. The pole supporting the vertical wire antenna is visible at center.
1372:
Marconi found suspending the metal plate "capacity area" high above the ground increased range.
8014:
7714:
7500:
7315:
7260:
7255:
7068:
7033:
5949:
5627:
2919:
Although their damping had been reduced as much as possible, spark transmitters still produced
2249:
2082:
1213:
842:
793:
The invention of the radio transmitter resulted from the convergence of two lines of research.
440:
The charge on the capacitor discharges as a current through the coil and spark gap. Due to the
268:
or tuning coil, connected together. The values of the capacitance and inductance determine the
121:
6615:
6551:
6518:
6437:
5885:
5551:
5282:
5161:
4308:
3886:
3837:
7616:
7420:
7385:
7305:
7285:
7207:
7095:
7016:
6275:
5216:
4808:
4713:
4245:
4157:
3144:
3067:. Vacuum tube oscillators were a far cheaper source of continuous waves, and could be easily
3045:
2190:
1408:
1245:
1146:
1122:
1121:
Hertz and the first generation of physicists who built these "Hertzian oscillators", such as
994:
430:
6949:
6892:
6789:...the number one maintenance item on a TIG machine is cleaning and adjusting the spark gap.
5392:, applied: 3 November 1899, complete specification: 30 June 1900, granted: 22 September 1900
4130:
3458:
2609:
5 ft diameter primary coil of oscillation transformer, consisting of 3 turns of specialized
2240:
atoms in the upper atmosphere, enabling them to return to Earth beyond the horizon. In 1924
900:
capacitor discharged through one spiral, would cause sparks in the gap of the other spiral.
7530:
7490:
7460:
7217:
7152:
6974:
6449:
5731:
2896:
2144:
1981:
1948:
1940:
1865:
1558:
1534:
1397:
1393:
1237:
1229:
1205:
1108:
881:
854:
636:
625:
457:
284:
264:) which stores high-voltage electricity from the transformer, and a coil of wire called an
141:
6503:
5509:
4730:
2355:
2116:
The temporary antenna used in the transatlantic transmission, a fan-shaped 50-wire aerial.
1508:
After failing to interest the Italian government, in 1896 Marconi moved to England, where
1334:
689:
The circuit which charges the capacitors, along with the spark gap itself, determines the
8:
8024:
7540:
7480:
7239:
7201:
6999:
6984:
6880:
6806:
6546:
On the Driving of Electromagnetic Vibrations by Electromagnetic and Electrostatic Engines
6026:, July 27, 1914 edition, Department of Commerce, United States government printing office
3830:
Fitzgerald, George "On the energy lost by radiation from alternating electric currents",
3603:
2964:
2666:
1513:
1435:
1318:
1201:
1197:
1069:
885:
838:
819:
738:
59:
6830:
6640:
6453:
6192:
5735:
4898:
4874:
4766:
4368:
Improvements in transmitting electrical impulses and signals, and in apparatus therefore
4223:
3934:
2850:, Germany was the most powerful radio transmitter in the world when it was built in 1911
1076:) which generated the oscillating currents. High-voltage pulses from the induction coil
512:
of the oscillations, which is the frequency of the emitted radio waves, is equal to the
7767:
7724:
7655:
7525:
7455:
7430:
7365:
7212:
6933:
6854:
6565:
6475:
5757:
5653:
5053:
4950:
3904:
3161:
3076:
3053:
3003:
2991:
2987:
2892:
2888:
2884:
2580:
2498:
2446:
2241:
2194:
1913:
1861:
1720:
1550:
1090:
788:
545:
522:
513:
495:
309:
1908:) and ground, forming an "open" resonant circuit with the capacitance of the antenna (
1627:
1546:
1350:
1021:
in 1894. Its 5-inch resonator ball produced waves of around 12 cm or 2.5 GHz
212:
168:
flowing through a conductor which suddenly change their velocity, thus accelerating.
7807:
7729:
7643:
7626:
7589:
7435:
7265:
7234:
7100:
6994:
6619:
6609:
6524:
5891:
5837:
5810:
5657:
5645:
5557:
5428:
5315:
5288:
5251:
5197:
5167:
5127:
5100:
5045:
4802:
4643:
4577:
4520:
4493:
4457:
4425:
4341:
4314:
4197:
4163:
4136:
4104:
4074:
4042:
4012:
3860:
3811:
3781:
3464:
3430:
3403:
3373:
3321:"Section 2.201: Emission, modulation, and transmission characteristics, footnote (f)"
3241:
3214:
3042:
2532:
1989:
1581:
1475:
1306:
1279:
1134:
823:
784:
482:
418:
305:
109:
7475:
5057:
38:, Austria. The spark gap is inside the box with the transparent cover at top center.
7812:
7772:
7752:
7719:
7648:
7606:
7520:
7375:
7360:
7335:
7310:
7270:
7120:
6979:
6964:
6826:
6520:
The Tentacles of Progress: Technology Transfer in the Age of Imperialism, 1850-1940
6479:
6470:
6465:
6457:
6394:
5945:
5761:
5752:
5747:
5739:
5637:
5037:
4635:
4604:
The Science of Radio: with MATLAB and Electronics Workbench demonstrations, 2nd Ed.
4257:
3674:
The Science of Radio: with MATLAB and Electronics Workbench demonstrations, 2nd Ed.
3156:
3117:
2976:
2960:
2900:
2659:, used until the Second International Radiotelegraphic Convention in 1906 at which
2537:
2403:
2233:
2067:
1985:
1929:
1837:
1711:
1621:
1613:
1590:
1585:
Circuit of Marconi's monopole transmitter and all other transmitters prior to 1897.
1404:
1400:
1252:
of 12 and 60 GHz respectively, using small metal balls as resonator-antennas.
1094:
834:
643:
639:
245:
195:
161:
34:
Low-power inductively coupled spark-gap transmitter on display in Electric Museum,
2859:
traffic with other countries and communicate with their overseas colonies. During
1976:
In addition to Tesla's system, inductively coupled radio systems were patented by
1639:
was that the radio transmissions were electrically "noisy"; they had a very large
7440:
7295:
7063:
7038:
7026:
5424:
Semiconductors and the Information Revolution: Magic Crystals that made IT Happen
4006:
3325:
Code of Federal Regulations, Title 47, Chapter I, Subchapter A, Part 2, Subpart C
3049:
2999:
2932:
2562:
2229:
2081:
In recognition of their achievements in radio, Marconi and Braun shared the 1909
1885:
1699:
1605:
1529:
In 1897 Marconi started a company to produce his radio systems, which became the
1518:
1283:
1256:
998:
655:
333:
297:
249:
191:
145:
94:
90:
86:
78:
6497:
2678:
Radio frequencies used by spark transmitters during the wireless telegraphy era
2155:
firing at different rates, and three resonant circuits, powered by a 25 kW
1608:
could be stored in the antenna before each spark, which was proportional to the
822:
in 1879 had also stumbled on radio wave transmission which he received with his
7638:
7510:
7485:
7445:
7415:
7290:
7125:
7078:
7053:
7011:
6138:
5473:
Tesla: Master of Lightning - companion site for 2000 PBS television documentary
5468:
3128:
3121:
3113:
3089:
3019:
2876:
2821:
2388:
2205:
1966:
1660:
1652:
1566:
1509:
1362:
1290:
1177:
1061:
1043:
877:
850:
846:
742:
708:
453:
449:
426:
361:
301:
238:
176:
67:
55:
4629:
4261:
1852:
is not an actual capacitor but represents the capacitance between the antenna
1060:
attached to the outer ends. The two sides of the antenna were connected to an
1005:
generated 60 GHz (5 mm) waves using 3 mm metal ball resonators.
7998:
7787:
7560:
7550:
7465:
7355:
7350:
7340:
7325:
7147:
7006:
6548:, read at the January 22, 1892 meeting of the Physical Society of London, in
6297:
5649:
5455:
5405:
5335:
5236:
5049:
4373:
3181:
3171:
3166:
3064:
2956:
2814:
2787:
2783:
2779:
2775:
2531:: In this type, invented by Fessenden around 1904, the rotor was turned by a
2399:
2066:
infringement but didn't have the resources to pursue the action. In 1943 the
1958:
1714:(also called tuned circuit or tank circuit) in transmitters would narrow the
1665:
1636:
1597:
1554:
1241:
1217:
1193:
1181:
1138:
1126:
1082:
964:
814:
810:
670:
647:
344:
98:
5389:
Improvements in or related to telegraphy without the use of continuous wires
5041:
1774:
Demonstration inductively coupled spark transmitter 1909, with parts labeled
7665:
7505:
7450:
7380:
7345:
7280:
7179:
7169:
7021:
4246:"On a complete apparatus for the study of the properties of electric waves"
3015:
2968:
2944:
2908:
2791:
2186:
2059:
1977:
1936:
1759:
1739:
1538:
1185:
1142:
1102:
1018:
862:
629:
149:
82:
6438:"Wireless Telegraphy, with special reference to the quenched-spark system"
6248:
6165:
5934:"The New Telefunken Telegraph: A combination of the arc and spark systems"
5720:"Wireless Telegraphy, with special reference to the quenched-spark system"
5641:
5252:"Misreading the Supreme Court: A Puzzling Chapter in the History of Radio"
4639:
3856:
The Science of Radio: with MATLAB and Electronics Workbench demonstrations
3807:
The Science of Radio: with MATLAB and Electronics Workbench demonstrations
3426:
The Science of Radio: with MATLAB and Electronics Workbench demonstrations
2625:
The three 5 ft rotary spark discharger wheels of the "timed spark" system.
2321:
Cross section of portion of quenched spark gap, consisting of metal disks
1819:, Nauen, Germany, showing large 360 Leyden jar 400 μF capacitor bank
456:. These oscillating fields radiate away from the antenna into space as an
7865:
7515:
7425:
7410:
7370:
7330:
7189:
6666:(5th ed.). Philadelphia: Lea and Febiger. pp. 187–188, 197–200.
5358:
5020:
Tesla is entitled to either distinct priority or independent discovery of
3127:
In the 1950s a Japanese toy company, Matsudaya, produced a line of cheap
3060:
3039:
2911:
at the base, 6 – 10 feet tall, to make it resonant with the transmitter.
2860:
2674:
2384:
2257:
1750:
1648:
1609:
1562:
1537:
to equip their ships with wireless stations. Marconi's company dominated
1449:, which recorded the Morse code symbols with an ink line on a paper tape.
1416:
1286:
1225:
1173:
1054:
1026:
729:
712:
517:
253:
226:
206:
172:
47:
6333:. San Francisco, California: Charles Shortridge. 7 July 1912. p. 22
5916:
Wireless Telegraphy, with special reference to the quenched-spark system
5705:
Wireless Telegraphy, with special reference to the quenched-spark system
5028:
Wheeler, L. P. (August 1943). "Tesla's contribution to high frequency".
2631:
Marconi 300 kW transatlantic timed spark transmitter built 1916 at
2162:
turned by a combustion engine. The first spark gap and resonant circuit
1495:
1455:
7870:
7577:
7275:
7184:
7140:
7110:
7088:
4100:
Radio's Conquest of Space: The experimental rise of radio communication
3104:
3100:
2995:
2940:
2935:
2880:
2632:
2434:
2237:
2156:
1953:
1921:
1731:
1570:
1522:
1221:
1165:
1161:
897:
889:
746:
674:
540:
474:
441:
422:
396:
348:
337:
261:
202:
153:
102:
51:
6869:
6216:
2998:) driven by an electric motor at a high enough speed that it produced
2277:
Ship radio room with 1.5 kW Telefunken quenched-spark transmitter
2236:
independently theorized that radio waves were reflected by a layer of
1702:
had given an influential lecture on radio in which he suggested using
7855:
7320:
7135:
6902:
6461:
5867:
Text-book on Wireless Telegraphy, Vol. 1: General Theory and Practice
5743:
3429:(2nd ed.). Springer Science and Business Media. pp. 27–28.
3108:
3068:
2904:
2610:
1935:
The first person to use resonant circuits in a radio application was
1727:
1703:
1644:
1617:
1249:
1209:
1154:
1073:
1047:
1035:
797:
771:
734:
651:
633:
490:
478:
465:
400:
322:
276:
269:
257:
180:
157:
6835:. Translated by Alfred E. Seelig. New York: McGraw-Hill Book Company
329:
in the resonant circuit, discharging the capacitor through the coil.
7850:
7840:
7757:
7582:
7405:
3516:
3011:
3010:
These transmitters, which could produce power outputs of up to one
2972:
2931:
From the beginning, physicists knew that another type of waveform,
2856:
2575:
2549:
2410:
2409:
In 1906, a new type of spark gap was developed by German physicist
2217:
2182:
1790:
next to tuning coil, on top of box containing glass plate capacitor
1754:
1743:
1735:
1601:
1384:
distributed current more equally between wires, reducing resistance
1299:
Evolution of Marconi's monopole antenna from Hertz's dipole antenna
893:
659:
367:
265:
234:
188:
165:
35:
6362:. New York, NY: James Gordon Bennett, Jr. 17 April 1912. p. 2
5836:(2nd ed.). Springer Science and Business Media. p. 972.
2899:(often below 1 ohm), so these transmitters required enormous wire
2842:
Telefunken 100 kW transoceanic quenched spark transmitter at
2189:
was building his own transatlantic radiotelegraphy transmitter on
1112:
Circuit of Hertz's spark oscillator and receiver. The interrupter
1101:
in loops of wire which functioned as resonant receiving antennas.
1093:
of the antenna, which was determined by its length; it acted as a
658:
range, typically 50 to 1000 sparks per second, so in a receiver's
7845:
7830:
7048:
5510:"No. 369 (1943) Marconi Wireless Co. of America v. United States"
3859:(2nd ed.). Springer Science and Business Media. p. 18.
3176:
3143:. Powerful spark gap pulse generators are still used to simulate
3133:
2798:
2202:
2052:
Marconi's inductively coupled transmitter patented 26 April 1900.
1710:) to reduce the bandwidth of transmitters and receivers. Using a
1424:
1150:
1046:
made of a pair of collinear metal rods of various lengths with a
912:
Heinrich Hertz discovering radio waves with his spark oscillator
230:
114:
30:
6191:
Moorcroft, John Harold; Pinto, A.; Curry, Walter Andrew (1921).
5077:
The Inventions, Researches and Writings of Nikola Tesla, 2nd Ed.
4340:(2nd ed.). UK: Cambridge University Press. pp. 37–39.
4073:(2nd ed.). UK: Cambridge University Press. pp. 34–36.
3881:
Report of the British Association for the Advancement of Science
3832:
Report of the British Association for the Advancement of Science
3810:(2nd ed.). Springer Science and Business Media. p. 7.
2020:
Braun's inductively coupled transmitter patented 3 November 1899
1216:. Hertz used them to perform historic experiments demonstrating
347:
to switch the transmitter on and off to communicate messages by
7875:
7835:
7157:
5806:
Communications: An International History of the Formative Years
4788:
The Design of CMOS Radio-Frequency Integrated Circuits, 2nd Ed.
4573:
Communications: An International History of the Formative Years
3096:, literally, "to spark", also means "to send a radio message".
3057:
2566:
2213:
2178:
1189:
1169:
845:. Maxwell's theory predicted that a combination of oscillating
666:
326:
184:
101:, creating pulses of radio waves to spell out text messages in
6594:. Hartford, CN: American Radio Relay league. pp. 123–124.
6139:"The first direct wireless messages from England to Australia"
5969:
British patent GB189620981 Henry Harris Lake for Nikola Tesla
1815:
Telefunken 25 kW long distance transmitter built 1906 at
1693:
of the first "syntonic" radio system, from Lodge's 1897 patent
1647:, but a continuous band of frequencies. They were essentially
1461:
British Post Office officials examining Marconi's transmitter
833:
The other was research by physicists to confirm the theory of
437:). This closes the circuit between the capacitor and the coil.
7860:
7797:
7105:
6553:
The Scientific Writings of the late George Francis Fitzgerald
3888:
The Scientific Writings of the Late George Francis Fitzgerald
3839:
The Scientific Writings of the Late George Francis Fitzgerald
3460:
The Continuous Wave: Technology and American Radio, 1900-1932
2924:
2847:
2636:
1168:
high-frequency waves with which they could duplicate classic
826:
detector, however he was persuaded that what he observed was
678:
614:{\displaystyle f={\frac {1}{2\pi }}{\sqrt {\frac {1}{LC}}}\,}
452:
around the antenna, while the voltage creates an oscillating
63:
6611:
The History of Communications - Electronics in the U.S. Navy
6277:
The History of Communications - Electronics in the U.S. Navy
4804:
The History of Communications - Electronics in the U.S. Navy
796:
One was efforts by inventors to devise a system to transmit
256:
when excited by the spark. A resonant circuit consists of a
7802:
6887:
3774:
Sarkar, T. K.; Mailloux, Robert; Oliner, Arthur A. (2006).
3297:(2nd ed.). New York: McGraw-Hill Book Co. pp. 6–9
2209:
221:
A practical spark gap transmitter consists of these parts:
6291:
6289:
6287:
5788:. This author misspells the word "quenched" as "squenched"
3352:
Contact at Sea: A History of Maritime Radio Communications
2244:
demonstrated the existence of this layer, now called the "
1376:
He found that a simple elevated wire worked just as well.
296:
transmitter. The spark gap and capacitor connected to the
97:; the operator switched the transmitter on and off with a
4873:
Ashley, Charles Grinnell; Hayward, Charles Brian (1912).
3327:. US Government Publishing Office website. 1 October 2007
2661:
2462:
A typical rotary spark gap used in low-power transmitters
2088:
1420:
1042:
See circuit diagram. Hertz's transmitters consisted of a
434:
4979:. London: The Electrician Publishing Co. pp. 50–58.
4857:
Improvements in Syntonized Telegraphy without Line Wires
4250:
The London, Edinburgh, and Dublin Philosophical Magazine
2939:
distances with a given output power. They could also be
1753:, storing oscillating electrical energy, increasing the
66:, from 1887 to the end of World War I. German physicist
6523:. New York: Oxford University Press. pp. 126–130.
6284:
5809:. Institute of Electrical Engineers. pp. 361–362.
4971:
Lodge's explanation of his syntonic radio system is in
4576:. Institute of Electrical Engineers. pp. 313–329.
4513:
Dosi, Giovanni; Teece, David J.; Chytry, Josef (2004).
4041:. Springer Science and Business Media. pp. 51–53.
4038:
Heinrich Hertz: Classical Physicist, Modern Philosopher
2895:, a tiny fraction of a wavelength tall, and so had low
1643:. These transmitters did not produce waves of a single
1328:, 1895 Metal sheets and spark balls not shown to scale.
1053:
between their inner ends and metal balls or plates for
809:, which had too short a range to be practical. In 1866
5830:
Bard, Allen J.; Inzelt, György; Scholz, Fritz (2012).
5163:
Intellectual Property Law for Engineers and Scientists
4337:
The Design of CMOS Radio-Frequency Integrated Circuits
4070:
The Design of CMOS Radio-Frequency Integrated Circuits
3366:
Serway, Raymond; Faughn, Jerry; Vuille, Chris (2008).
1160:
To investigate the similarity between radio waves and
662:
the signal sounds like a steady tone, whine, or buzz.
6055:"The Marconi Timed-Spark Continuous-Wave Transmitter"
3510:
3508:
3506:
3504:
3502:
3500:
2994:, was a huge rotating alternating current generator (
2177:
The transmitter was built in secrecy on the coast at
571:
548:
525:
498:
6556:. London: Longmans, Green and Co. pp. 277–281.
6321:
6319:
6210:
6208:
6145:. VK2DYM's military radio and radar information site
5475:. PBS.org, Public Broadcasting Service website. 2000
5382:
5380:
3773:
3498:
3496:
3494:
3492:
3490:
3488:
3486:
3484:
3482:
3480:
3206:
3107:
it was used until the 1940s in the medical field of
3038:
All these early technologies were superseded by the
1200:. Their short antennas generated radio waves in the
1164:, these researchers concentrated on producing short
6190:
5975:
filed: 22 September 1896, granted: 21 November 1896
5386:British patent no. 189922020 Karl Ferdinand Braun,
4815:
4220:, Vol. 36, December 13, 1988, p. 769, reprinted in
4034:
3842:. London: Hodges, Figgis, and Co. pp. 128–129.
3237:
Academic Press Dictionary of Science and Technology
2170:powering the second spark gap and resonant circuit
2166:generated the high voltage to charge the capacitor
1600:oscillator (in modern terminology, it had very low
1356:
Re-creation of Marconi's first monopole transmitter
316:, creating less interference to other transmitters.
6422:. New York: Wireless Press, Inc. pp. 288–307.
6042:. New York: Wireless Press, Inc. pp. 274–275.
5870:. London: Longmans Green and Co. pp. 200–204.
5596:. London: Longmans Green and Co. pp. 449–454.
5408:, filed: 8 February 1900, granted: 2 December 1902
3927:Hertz, H., "On very rapid electric oscillations",
3365:
2518:There were two types of rotary spark transmitter:
2208:with a 400 ft. wire antenna suspended from a
1651:sources radiating energy over a large part of the
684:
613:
554:
531:
504:
6316:
6205:
5458:, filed: 10 November 1900, granted: 28 June 1904.
5452:Improvements in apparatus for wireless telegraphy
5377:
5359:"Nikola Tesla: The Guy Who DIDN'T "Invent Radio""
5338:, filed: 1 February 1898, granted: 16 August 1898
5240:, filed: 2 September 1897; granted: 20 March 1900
4823:"Reporting the yacht races by wireless telegraph"
3477:
3034:Marconi 2 kilowatt ship spark transmitter, 1920.
1749:The resonant circuit functioned analogously to a
1441:Marconi in 1901 with his early spark transmitter
1153:like existing optical signalling methods such as
927:Hertz's drawing of one of his spark oscillators.
7996:
6860:Fessenden and the Early History of Radio Science
6775:. Lincoln Electric website. 2006. Archived from
6765:
6093:. New York: Wireless Press, Inc. pp. 73–75.
5991:. London: Ernst Benn, Ltd. pp. 25, 138–148.
5829:
4361:
4359:
4357:
4008:Wireless: From Marconi's Black-box to the Audion
3548:. London: Longmans Green and Co. pp. 15–16.
2986:transmitter, developed between 1906 and 1915 by
2224:, a distance of 2100 miles (3400 km).
1589:The primitive transmitters prior to 1897 had no
6491:
6489:
6000:
5998:
5446:
5444:
5400:
5398:
5230:
5228:
5126:. Barnes and Noble Publishing. pp. 65–70.
4512:
4377:, filed 7 December 1896, accepted: 13 July 1897
3372:(8th ed.). Cengage Learning. p. 714.
3207:Hempstead, Colin; Worthington, William (2005).
2556:
2248:" or "E-layer", for which he received the 1947
1489:Induction coil, telegraph key, and battery box.
248:(tuned circuits or tank circuits) which create
6877:"The Sounds of a Spark Transmitter with audio"
6502:. Scientific American Publishing Co. pp.
6353:"President Moves to Stop Mob Rule of Wireless"
6345:
5196:. Greenwood Publishing Group. pp. 21–23.
4879:. American School of Correspondence. pp.
4850:
4848:
4722:
4413:
4411:
4409:
4407:
4405:
4403:
4302:
4300:
4298:
4035:Baird, D.; Hughes, R.I.; Nordmann, A. (2013).
3891:. London: Hodges, Figgis, and Co. p. 129.
3402:. Cambridge University Press. pp. 16–17.
3240:. Gulf Professional Publishing. p. 2045.
2263:
2004:Tesla's inductively coupled power transmitter
1089:. The frequency of the waves was equal to the
896:with their conductors ending in spark gaps. A
728:In higher power transmitters powered by AC, a
417:When the voltage on the capacitor reaches the
6918:
6898:Spark gap transmitter history & operation
6249:"Section 12: Pioneering Amateurs (1900-1912)"
6097:
6024:Radio Communication Laws of the United States
6012:. United States Congress. 1912. pp. 6–14
5879:
5877:
5777:
5775:
5773:
5771:
5545:
5543:
5541:
5539:
5537:
5535:
5533:
5531:
4872:
4860:filed: May 10, 1897, granted: August 10, 1898
4516:Understanding Industrial and Corporate Change
4445:
4443:
4441:
4401:
4399:
4397:
4395:
4393:
4391:
4389:
4387:
4385:
4383:
4354:
4296:
4294:
4292:
4290:
4288:
4286:
4284:
4282:
4280:
4278:
3452:
3450:
3448:
3446:
3124:generators or "Bovies" as late as the 1980s.
3088:One legacy of spark-gap transmitters is that
1145:, were mainly interested in radio waves as a
650:used during the wireless telegraphy era. The
6570:: CS1 maint: multiple names: authors list (
6486:
6431:
6429:
5995:
5450:British patent no. 7777, Guglielmo Marconi,
5441:
5395:
5328:
5225:
4671:
4669:
4365:British patent 189612039 Marconi, Guglielmo
4185:
4183:
4181:
4179:
2649:
1262:
7933:Global telecommunications regulation bodies
6603:
6601:
6537:
6495:
6383:"Marconi´s 200kW transatlantic transmitter"
5963:
5909:
5907:
5859:
5857:
5855:
5853:
5784:The Worldwide History of Telecommunications
5698:
5696:
5694:
5334:US Patent no. 609,154 Oliver Joseph Lodge,
5237:System of transmission of electrical energy
5096:Biographical Encyclopedia of American Radio
5088:
5086:
5072:On light and other high frequency phenomena
4988:
4986:
4903:. New York: Moffat, Yard, and Co. pp.
4900:Wireless Telegraphy: An Elementary Treatise
4845:
4557:The Worldwide History of Telecommunications
4453:The Worldwide History of Telecommunications
4196:. The Rosen Publishing Group. p. 159.
3873:
3824:
3391:
3389:
3344:
3342:
3201:
3199:
3197:
2185:, UK. Marconi was pressed for time because
1992:) between the primary and secondary coils.
1017:Microwave spark oscillator demonstrated by
766:In a transmitter with a "rotary" spark gap
516:of the resonant circuit, determined by the
433:to a very low level (usually less than one
62:or "spark" era, the first three decades of
7969:
6925:
6911:
6773:"TIG Welding Series: The Power to Perform"
6374:
6242:
6240:
6238:
6184:
6010:Public 264 S. 6412 approved 13 August 1912
5950:10.1038/scientificamerican06191909-390supp
5874:
5768:
5617:
5615:
5613:
5611:
5609:
5607:
5605:
5603:
5593:The Principles of Electric Wave Telegraphy
5585:
5583:
5581:
5579:
5577:
5575:
5573:
5528:
5155:
5153:
5151:
5149:
5147:
5145:
5143:
4868:
4866:
4771:. New York: McGraw-Hill Book Co. pp.
4760:
4758:
4756:
4754:
4752:
4709:
4707:
4705:
4703:
4623:
4621:
4619:
4617:
4615:
4613:
4548:
4481:
4479:
4477:
4475:
4473:
4438:
4380:
4275:
4092:
4090:
3909:. New York: McGraw Hill Book Co. pp.
3884:
3835:
3769:
3767:
3765:
3763:
3761:
3759:
3757:
3755:
3753:
3751:
3749:
3747:
3745:
3743:
3741:
3739:
3737:
3735:
3733:
3731:
3729:
3727:
3725:
3723:
3721:
3719:
3717:
3715:
3713:
3711:
3709:
3707:
3705:
3703:
3608:. New York: John Wiley and Sons. pp.
3567:
3565:
3563:
3561:
3559:
3557:
3555:
3545:The Principles of Electric Wave Telegraphy
3443:
2827:, only a few miles away, did not hear the
2486:1 kilowatt rotary spark transmitter, 1914.
2440:
2325:separated by thin insulating mica washers
1965:. However, Tesla was mainly interested in
6893:Radio Technology in common use circa 1914
6872:The new England Wireless and Steam Museum
6804:
6713:"Flotsam & Jetsam – Control by Radio"
6510:
6469:
6426:
6380:
6136:
6130:
6086:
6080:
5883:
5798:
5796:
5794:
5751:
5631:
5549:
5352:
5350:
5348:
5346:
5344:
5166:. John Wiley and Sons. pp. 196–199.
4965:
4666:
4597:
4595:
4593:
4456:. John Wiley and Sons. pp. 207–209.
4449:
4306:
4189:
4176:
4155:
4149:
3923:
3921:
3799:
3797:
3701:
3699:
3697:
3695:
3693:
3691:
3689:
3687:
3685:
3683:
3601:
3595:
3395:
3348:
3260:
1635:A more significant drawback of the large
610:
6731:
6598:
6516:
6409:
6267:
6006:"An act to regulate radio communication"
5931:
5904:
5850:
5711:
5691:
5670:
5664:
5416:
5414:
5404:US Patent no. 714,756, John Stone Stone
5185:
5183:
5092:
5083:
4983:
4896:
4890:
4854:British patent GB189711575 Lodge, O. J.
4675:
4030:
4028:
4000:
3998:
3996:
3994:
3992:
3990:
3988:
3986:
3984:
3982:
3980:
3978:
3976:
3974:
3903:Zenneck, Jonathan Adolf Wilhelm (1915).
3637:
3635:
3633:
3631:
3629:
3627:
3625:
3623:
3621:
3619:
3535:
3386:
3339:
3286:
3284:
3263:"The spark era - the beginning of radio"
3254:
3194:
3029:
2837:
2361:Ordinary inductively coupled transmitter
2329:to make multiple microscopic spark gaps
2130:
2122:
2032:Stone's inductively coupled transmitter
1912:). Both circuits were tuned to the same
1884:" transmitter. See circuit diagram. The
1843:
1680:
1676:
1626:
1580:
1423:) in the upper atmosphere, later called
1107:
1025:
997:in 1894 was the first person to produce
628:with a steady frequency, so it could be
366:
211:
29:
6825:
6738:Findlay, David A. (September 1, 1957).
6737:
6704:
6653:
6632:
6435:
6295:
6235:
6214:
6157:
6052:
6046:
6029:
5927:
5925:
5717:
5621:
5600:
5589:
5570:
5502:
5210:
5159:
5140:
5064:
5027:
5012:
4992:
4936:
4930:
4924:Syntony and Spark: The origins of radio
4863:
4794:
4749:
4728:
4700:
4627:
4610:
4492:. John Wiley and Sons. pp. 30–33.
4470:
4421:Syntony and Spark: The Origins of Radio
4244:Bose, Jagadish Chandra (January 1897).
4193:The Britannica Guide to Sound and Light
4124:
4122:
4120:
4087:
4062:
4060:
4058:
3972:
3970:
3968:
3966:
3964:
3962:
3960:
3958:
3956:
3954:
3902:
3896:
3571:
3552:
3541:
3514:
3210:Encyclopedia of 20th-Century Technology
2975:atmosphere to excite oscillations in a
2959:(Poulsen arc) transmitter, invented by
1848:Inductively coupled spark transmitter.
871:
837:proposed in 1864 by Scottish physicist
14:
7997:
6932:
6710:
6659:
6638:
6607:
6578:
6549:
6415:
6273:
6166:"Section 12: Radio at Sea (1891-1922)"
6053:Coursey, Phillip R. (September 1919).
6035:
5978:
5863:
5791:
5487:
5341:
5249:
5243:
5074:", in Thomas Cummerford Martin (1894)
5022:" three concepts in wireless theory: "
4914:
4800:
4764:
4731:"Aerials, Attachments, and Audibility"
4590:
4563:
4533:
4485:
4417:
4210:
4096:
3918:
3846:
3794:
3680:
3665:
3581:The history of QST Vol. 1 - Technology
3456:
3290:
3233:
2089:First transatlantic radio transmission
1969:and never developed a practical radio
699:one of three types of power circuits:
477:wave that increases rapidly to a high
382:Audio of Massie spark gap transmission
136:
6906:
6740:"Radio Controlled Toys Use Spark Gap"
6670:
6584:
6246:
6163:
5984:
5802:
5671:Margolis, Laurie (11 December 2001).
5622:Belrose, John S. (5 September 1995).
5420:
5411:
5356:
5307:
5301:
5193:Radio: The Life Story of a Technology
5189:
5180:
4976:Signaling through space without wires
4972:
4937:Crookes, William (February 1, 1892).
4569:
4489:Array and Phased Array Antenna Basics
4221:
4025:
3932:
3931:, Vol. 31, p. 421, 1887 reprinted in
3852:
3803:
3641:
3616:
3422:
3416:
3359:
3314:
3312:
3281:
3227:
2193:, in a bid to be first (this was the
1904:) was connected to the wire antenna (
1831:
861:had calculated the output power of a
752:
654:of repetition (spark rate) is in the
421:of the spark gap, the air in the gap
7979:
6676:
6588:The Radio Amateur's Handbook, 1st Ed
6105:"Great Wireless Stations: Carnarvon"
5922:
5823:
5516:. Findlaw.com website. June 21, 1943
5514:United States Supreme Court decision
5357:White, Thomas H. (1 November 2012).
5274:
5234:US Patent No. 645576, Nikola Tesla,
4779:
4506:
4327:
4243:
4237:
4234:translated to English by D. E. Jones
4117:
4055:
4004:
3951:
3948:translated to English by D. E. Jones
3653:. American Radio Relay League: 29–32
2474:Small rotary spark transmitter, 1918
2297:oscillation transformer, Leyden jars
1481:Marconi's transmitter in July 1897.
1172:experiments with radio waves, using
1034:was applied, it produced waves at a
733:maximum voltage, at peaks of the AC
6813:. New York: Wiley. pp. 275–363
5461:
5280:
5119:
5113:
4993:Marconi, Guglielmo (May 24, 1901).
4939:"Some Possibilities of Electricity"
4628:Thrower, K. R. (5 September 1995).
4333:
4128:
4066:
2914:
2790:from early automobiles such as the
2672:, in which 1500 people were saved.
761:
371:Demonstration of the restored 1907
325:which acts as a voltage-controlled
160:, can be generated by time-varying
24:
6798:
6381:Pickworth, George (January 1994).
5250:Wunsch, A. David (November 1998).
3355:. The Gregg Press. pp. 26–30.
3309:
1862:inductively (magnetically) coupled
1569:in Germany who in 1903 formed the
1531:Marconi Wireless Telegraph Company
853:could travel through space as an "
354:
25:
8036:
6848:
6811:Principles of Radio Communication
6253:United States Early Radio History
6194:Principles of Radio Communication
6170:United States Early Radio History
5456:Apparatus for wireless telegraphy
5363:United States Early Radio History
5093:Sterling, Christopher H. (2013).
4678:"United States Radio Development"
4676:Marriott, Robert H. (June 1917).
3605:Principles of Radio Communication
3523:. C. F. Codella's private website
3291:Terman, Frederick Emmons (1937).
723:
702:
681:that breaks the primary circuit.
156:, electromagnetic waves of radio
77:; they are unable to produce the
7978:
7968:
7959:
7958:
7947:
7568:Free-space optical communication
6663:Electrotherapy and Light Therapy
6639:Strong, Frederick Finch (1908).
6560:from the original on 2014-07-07.
6296:Codella, Christopher F. (2016).
6215:Codella, Christopher F. (2016).
6197:. John Wiley and Sons. pp.
6172:. T. H. White's personal website
6143:Australian Amateur Radio History
5932:von Arco, Georg (19 June 1909).
5590:Fleming, John Archibald (1906).
5365:. T. H. White's personal website
4765:Jansky, Cyril Methodius (1919).
4729:Codella, Christopher F. (2016).
3542:Fleming, John Archibald (1906).
3515:Codella, Christopher F. (2016).
3261:Champness, Rodney (April 2010).
2618:
2602:
2590:
2506:
2491:
2479:
2467:
2455:
2368:
2354:
2338:
2314:
2302:
2282:
2270:
2256:could have mistaken atmospheric
2109:
2097:
2045:
2025:
2013:
1997:
1888:of the oscillation transformer (
1808:
1795:
1779:
1767:
1576:
1494:
1474:
1454:
1434:
1361:
1349:
1333:
1317:
1305:
1010:
987:
975:
940:
920:
905:
888:in 1864, in which he discovered
386:
6888:The Sparks Telegraph Key Review
6805:Morecroft, John Harold (1921).
6711:Parker, John (September 2017).
6645:. New York: Rebman Co. p.
6496:Lescarboura, Austin C. (1922).
5287:. McFarland. pp. 111–113.
5099:. Routledge. pp. 382–383.
4897:Kennelly, Arthur Edwin (1906).
4833:(15): 596–597. October 12, 1901
4374:Transmitting electrical signals
4228:. Dover Publications. pp.
4135:. McFarland. pp. 4–6, 13.
3939:. Dover Publications. pp.
3234:Morris, Christopher G. (1992).
3213:. Routledge. pp. 649–650.
3205:"Radio Transmitters, Early" in
3025:
2875:to link the possessions of the
1240:, differing only in frequency.
685:Charging circuit and spark rate
260:(in early days a type called a
6585:Handy, Frances Edward (1926).
6436:Leggett, Bernard John (1921).
6280:. U.S. Navy. pp. 69, 117.
5938:Scientific American Supplement
5718:Leggett, Bernard John (1921).
5427:. Academic Press. p. 37.
4995:"Syntonic Wireless Telegraphy"
3642:Hyder, Harry R. (March 1992).
3463:. Princeton University Press.
2289:Tuned circuit of transmitter.
1924:capacitor banks filling rooms
13:
1:
6419:Practical Wireless Telegraphy
6118:(78): 301–307. September 1919
6087:Goldsmith, Alfred N. (1918).
6039:Practical Wireless Telegraphy
4768:Principles of Radiotelegraphy
4162:. Da Capo Press. p. 52.
3644:"The final days of ham spark"
3583:. American Radio Relay League
3574:"How spark transmitters work"
3396:Ellingson, Steven W. (2016).
3187:
2151:with two cascaded spark gaps
272:of the radio waves produced.
120:disaster. After World War I,
7954:Telecommunication portal
7735:Telecommunications equipment
6677:Carr, Joseph J. (May 1990).
6550:Larmor, Joseph, Ed. (1902).
6517:Headrick, Daniel R. (1988).
5406:Method of electric signaling
5314:. Dockside Consultants Inc.
5311:Lightning: Fire from the Sky
4450:Huurdeman, Anton A. (2003).
3883:, 1883, p.405, reprinted in
3349:Schroeder, Peter B. (1967).
2813:distress calls summoned the
2557:Marconi's timed spark system
1573:Co., Marconi's chief rival.
304:that induced current in the
131:radio frequency interference
7:
8005:History of radio technology
7471:Alexander Stepanovich Popov
6327:"To Check Wireless Anarchy"
6304:. Codella's private website
6223:. Codella's private website
5160:Rockman, Howard B. (2004).
4737:. Codella's private website
4519:. OUP Oxford. p. 251.
4486:Visser, Hubregt J. (2006).
4216:Hertz, H., "On radiation",
3885:Fitzgerald, George (1902).
3836:Fitzgerald, George (1902).
3602:Morecroft, John H. (1921).
3150:
2774:Spark transmitters and the
2745:Moderate size land stations
2548:" (this is equivalent to a
2264:Quenched-spark transmitters
1945:wireless power transmission
718:mercury turbine interrupter
10:
8041:
7175:Telecommunications history
6679:"Early radio transmitters"
5833:Electrochemical Dictionary
5803:Burns, Russell W. (2004).
5123:Tesla, Master of Lightning
4570:Burns, Russell W. (2004).
4418:Aitken, Hugh G.J. (1985).
4103:. Murray Hill Books, Inc.
3457:Aitken, Hugh G.J. (2014).
2865:submarine telegraph cables
2702:
2433:The German wireless giant
2375:Quenched-spark transmitter
2141:submarine telegraph cables
2135:View of Poldhu transmitter
782:
778:
745:with its shaft turning an
8020:Electric power conversion
7942:
7884:
7821:
7783:Public Switched Telephone
7743:
7707:
7664:
7605:
7595:telecommunication circuit
7556:Fiber-optic communication
7539:
7301:Francis Blake (telephone)
7248:
7096:Optical telecommunication
6940:
6855:Alternator, Arc and Spark
6416:Bucher, Elmer E. (1917).
6247:White, Thomas H. (2003).
6164:White, Thomas H. (2003).
6137:MacKinnon, Colin (2004).
6036:Bucher, Elmer E. (1917).
5988:Radio: Beam and Broadcast
5890:. IET. pp. 194–197.
5556:. IET. pp. 192–194.
5496:Radio: Beam and Broadcast
5284:Wireless Radio: A History
4949:: 174–176. Archived from
4542:Radio: Beam and Broadcast
4424:. Princeton Univ. Press.
4313:. IET. pp. 186–190.
4262:10.1080/14786449708620959
4156:Weightman, Gavin (2009).
4132:Wireless Radio: A History
3399:Radio Systems Engineering
3083:
2844:Nauen Transmitter Station
2677:
2222:Signal Hill, Newfoundland
2008:patented 2 September 1897
1817:Nauen Transmitter Station
1368:Early vertical antennas.
1312:Hertz's dipole oscillator
1263:Non-syntonic transmitters
807:electromagnetic induction
632:in a radio receiver by a
539:of the capacitor and the
27:Type of radio transmitter
7694:Orbital angular-momentum
7131:Satellite communications
6970:Communications satellite
6870:Massie Spark Transmitter
6660:Kovács, Richard (1945).
5864:Rupert, Stanley (1919).
5782:Huurdeman, Anton (2003)
5308:Smith, Craig B. (2008).
5217:Cheney, Margaret (2011)
4682:Proceedings of the I.R.E
4555:Huurdeman, Anton (2003)
4222:Hertz, Heinrich (1893).
4190:Gregersen, Erik (2011).
4097:Donald, McNicol (1946).
3933:Hertz, Heinrich (1893).
3141:gas tungsten arc welding
2871:, which constructed the
2246:Kennelly–Heaviside layer
2040:patented 8 February 1900
1984:, in November 1899, and
1823:and vertical spark gaps
1485:4 ball Righi spark gap,
171:An electrically charged
122:vacuum tube transmitters
7573:Molecular communication
7396:Gardiner Greene Hubbard
7225:Undersea telegraph line
6960:Cable protection system
6642:High Frequency Currents
6471:2027/mdp.39015063598398
6298:"The first regulations"
5914:Bernard Leggett (1921)
5884:Beauchamp, Ken (2001).
5753:2027/mdp.39015063598398
5703:Bernard Leggett (1921)
5550:Beauchamp, Ken (2001).
5421:Orton, John W. (2009).
5042:10.1109/EE.1943.6435874
4714:Ashley, Hayward (1912)
4334:Lee, Thomas H. (2004).
4307:Beauchamp, Ken (2001).
4067:Lee, Thomas H. (2004).
3853:Nahin, Paul J. (2001).
3804:Nahin, Paul J. (2001).
3780:. John Wiley and Sons.
3423:Nahin, Paul J. (2001).
2984:Alexanderson alternator
2873:Imperial Wireless Chain
2641:Alexanderson alternator
2441:Rotary gap transmitters
1872:); this was called an "
1870:oscillation transformer
1214:television transmitters
1001:; his spark oscillator
803:electrostatic induction
375:spark gap transmitter
373:Massie Wireless Station
290:oscillation transformer
229:, to transform the low-
46:is an obsolete type of
7715:Communication protocol
7501:Charles Sumner Tainter
7316:Walter Houser Brattain
7261:Edwin Howard Armstrong
7069:Information revolution
6865:Brief history of spark
6719:. MyTimeMedia Ltd., UK
6614:. U.S. Navy. pp.
6608:Howeth, L. S. (1963).
6393:(1718). Archived from
6274:Howeth, L. S. (1963).
6255:. earlyradiohistory.us
5219:Tesla: Man Out Of Time
5030:Electrical Engineering
4973:Lodge, Oliver (1900).
4943:The Fortnightly Review
4807:. U.S. Navy. pp.
4801:Howeth, L. S. (1963).
4601:Nahin, Paul J. (2001)
4005:Hong, Sungook (2010).
3671:Nahin, Paul J. (2001)
3048:, invented in 1912 by
3035:
2851:
2250:Nobel Prize in Physics
2136:
2128:
2083:Nobel Prize in physics
1892:) with the capacitor (
1857:
1694:
1632:
1616:", "inverted-L", and "
1586:
1413:horizontally polarized
1411:waves, instead of the
1278:Italian radio pioneer
1276:
1248:around 1894 generated
1118:
1039:
615:
556:
533:
506:
409:
218:
175:discharged through an
39:
7689:Polarization-division
7421:Narinder Singh Kapany
7386:Erna Schneider Hoover
7306:Jagadish Chandra Bose
7286:Alexander Graham Bell
7017:online video platform
5985:Morse, A. H. (1925).
5887:History of Telegraphy
5553:History of Telegraphy
5469:"Who invented radio?"
5190:Regal, Brian (2005).
4953:on September 29, 2018
4310:History of Telegraphy
3834:, 1883, reprinted in
3572:Kennedy, Hal (1990).
3046:electronic oscillator
3033:
2841:
2759:Transoceanic stations
2191:Long Island, New York
2134:
2126:
1847:
1684:
1677:Syntonic transmitters
1659:with each other. The
1630:
1584:
1445:and coherer receiver
1266:
1246:Jagadish Chandra Bose
1238:electromagnetic waves
1147:scientific phenomenon
1123:Jagadish Chandra Bose
1111:
1029:
995:Jagadish Chandra Bose
882:electromagnetic waves
783:Further information:
616:
557:
534:
507:
370:
292:. This was called an
215:
142:Electromagnetic waves
44:spark-gap transmitter
33:
18:Spark gap transmitter
7531:Vladimir K. Zworykin
7491:Almon Brown Strowger
7461:Charles Grafton Page
7116:Prepaid mobile phone
7044:Electrical telegraph
5120:Uth, Robert (1999).
4922:Aitken, Hugh (2014)
4909:selective signaling.
4885:selective signaling.
4786:Lee, Thomas H. 2004
3063:invented in 1906 by
2897:radiation resistance
2145:John Ambrose Fleming
2063:(J in circuit above)
1982:Karl Ferdinand Braun
1949:resonant transformer
1941:resonant transformer
1926:(see pictures above)
1866:resonant transformer
1758:tuned circuit using
1559:Karl Ferdinand Braun
1409:vertically polarized
1198:diffraction gratings
872:Hertzian oscillators
855:electromagnetic wave
569:
546:
523:
496:
458:electromagnetic wave
285:resonant transformer
201:Due to the inherent
7481:Johann Philipp Reis
7240:Wireless revolution
7202:The Telephone Cases
7059:Hydraulic telegraph
6832:Wireless Telegraphy
6717:Model Boats website
6686:Popular Electronics
6499:Radio for Everybody
6454:1921Natur.107..390.
5736:1921Natur.107..390.
5642:10.1049/cp:19950787
5336:Electric Telegraphy
5281:Coe, Lewis (2006).
4640:10.1049/cp:19950799
4218:Wiedemann's Annalen
4129:Coe, Lewis (2006).
3929:Wiedemann's Annalen
3906:Wireless Telegraphy
3777:History of Wireless
3267:Silicon Chip Online
2965:negative resistance
2885:Paper tape machines
1939:, who invented the
1874:inductively coupled
1514:General Post Office
1176:components such as
1070:harmonic oscillator
886:James Clerk Maxwell
843:Maxwell's equations
839:James Clerk Maxwell
820:David Edward Hughes
626:amplitude modulated
294:inductively-coupled
137:Theory of operation
60:wireless telegraphy
7679:Frequency-division
7656:Telephone exchange
7526:Charles Wheatstone
7456:Jun-ichi Nishizawa
7431:Innocenzo Manzetti
7366:Reginald Fessenden
7101:Optical telegraphy
6934:Telecommunications
6807:"Spark Telegraphy"
6331:San Francisco Call
5673:"Faking the waves"
3162:Invention of radio
3054:Alexander Meissner
3036:
3004:very low frequency
2992:Ernst Alexanderson
2988:Reginald Fessenden
2948:continuous waves.
2893:electrically short
2889:very low frequency
2852:
2447:Reginald Fessenden
2385:coupled oscillator
2242:Edward V. Appleton
2195:Wardenclyffe Tower
2137:
2129:
1980:in February 1898,
1914:resonant frequency
1858:
1832:Inductive coupling
1721:resonant frequency
1695:
1633:
1587:
1551:Reginald Fessenden
1119:
1091:resonant frequency
1040:
1038:of roughly 50 MHz.
789:Invention of radio
753:Quenched spark gap
611:
552:
529:
514:resonant frequency
502:
485:to zero, called a
410:
310:resonant frequency
219:
85:(sound) in modern
40:
8010:Radio electronics
7992:
7991:
7730:Store and forward
7725:Data transmission
7639:Network switching
7590:Transmission line
7436:Guglielmo Marconi
7401:Internet pioneers
7266:Mohamed M. Atalla
7235:Whistled language
6883:on July 18, 2011.
6827:Zenneck, Jonathan
6448:(2691): 299–305.
6387:Electronics World
6302:Ham Radio History
6221:Ham Radio History
5321:978-0-615-24869-1
4735:Ham Radio History
4631:History of tuning
3521:Ham Radio History
3294:Radio Engineering
3056:, which used the
2963:in 1904 used the
2879:, and the German
2809:radio operator's
2776:crystal receivers
2772:
2771:
2533:synchronous motor
2428:(see lower graph)
2201:using an untuned
1990:mutual inductance
1896:) and spark gap (
1591:resonant circuits
1535:Lloyd's of London
1401:monopole antennas
1280:Guglielmo Marconi
1273:Guglielmo Marconi
1135:Frederick Trouton
1131:George Fitzgerald
1064:(Ruhmkorff coil)
955:, induction coil
876:German physicist
859:George Fitzgerald
824:carbon microphone
785:Timeline of radio
608:
607:
591:
555:{\displaystyle L}
532:{\displaystyle C}
505:{\displaystyle f}
419:breakdown voltage
391:
306:secondary winding
246:resonant circuits
241:(Ruhmkorff coil).
196:electric currents
162:electric currents
110:Guglielmo Marconi
48:radio transmitter
16:(Redirected from
8032:
7982:
7981:
7972:
7971:
7962:
7961:
7952:
7951:
7950:
7823:Notable networks
7813:Wireless network
7753:Cellular network
7745:Types of network
7720:Computer network
7607:Network topology
7521:Thomas A. Watson
7376:Oliver Heaviside
7361:Philo Farnsworth
7336:Daniel Davis Jr.
7311:Charles Bourseul
7271:John Logie Baird
6980:Data compression
6975:Computer network
6927:
6920:
6913:
6904:
6903:
6884:
6879:. Archived from
6844:
6842:
6840:
6822:
6820:
6818:
6792:
6791:
6786:
6784:
6769:
6763:
6762:
6760:
6758:
6744:
6735:
6729:
6728:
6726:
6724:
6708:
6702:
6701:
6699:
6697:
6683:
6674:
6668:
6667:
6657:
6651:
6650:
6636:
6630:
6629:
6605:
6596:
6595:
6593:
6582:
6576:
6575:
6569:
6561:
6541:
6535:
6534:
6514:
6508:
6507:
6493:
6484:
6483:
6473:
6462:10.1038/107390b0
6433:
6424:
6423:
6413:
6407:
6406:
6404:
6402:
6378:
6372:
6371:
6369:
6367:
6357:
6349:
6343:
6342:
6340:
6338:
6323:
6314:
6313:
6311:
6309:
6293:
6282:
6281:
6271:
6265:
6264:
6262:
6260:
6244:
6233:
6232:
6230:
6228:
6217:"The Squeak Box"
6212:
6203:
6202:
6188:
6182:
6181:
6179:
6177:
6161:
6155:
6154:
6152:
6150:
6134:
6128:
6127:
6125:
6123:
6109:
6101:
6095:
6094:
6084:
6078:
6077:
6075:
6073:
6059:
6050:
6044:
6043:
6033:
6027:
6021:
6019:
6017:
6002:
5993:
5992:
5982:
5976:
5967:
5961:
5960:
5958:
5956:
5929:
5920:
5911:
5902:
5901:
5881:
5872:
5871:
5861:
5848:
5847:
5827:
5821:
5820:
5800:
5789:
5779:
5766:
5765:
5755:
5744:10.1038/107390b0
5715:
5709:
5700:
5689:
5688:
5686:
5684:
5668:
5662:
5661:
5635:
5619:
5598:
5597:
5587:
5568:
5567:
5547:
5526:
5525:
5523:
5521:
5506:
5500:
5491:
5485:
5484:
5482:
5480:
5465:
5459:
5448:
5439:
5438:
5418:
5409:
5402:
5393:
5384:
5375:
5374:
5372:
5370:
5354:
5339:
5332:
5326:
5325:
5305:
5299:
5298:
5278:
5272:
5271:
5269:
5267:
5247:
5241:
5232:
5223:
5214:
5208:
5207:
5187:
5178:
5177:
5157:
5138:
5137:
5117:
5111:
5110:
5090:
5081:
5068:
5062:
5061:
5016:
5010:
5009:
5007:
5005:
4990:
4981:
4980:
4969:
4963:
4962:
4960:
4958:
4934:
4928:
4918:
4912:
4911:
4894:
4888:
4887:
4870:
4861:
4852:
4843:
4842:
4840:
4838:
4827:Electrical World
4819:
4813:
4812:
4798:
4792:
4783:
4777:
4776:
4762:
4747:
4746:
4744:
4742:
4726:
4720:
4711:
4698:
4697:
4695:
4693:
4673:
4664:
4660:
4658:
4656:
4625:
4608:
4599:
4588:
4587:
4567:
4561:
4552:
4546:
4537:
4531:
4530:
4510:
4504:
4503:
4483:
4468:
4467:
4447:
4436:
4435:
4415:
4378:
4363:
4352:
4351:
4331:
4325:
4324:
4304:
4273:
4272:
4270:
4268:
4241:
4235:
4233:
4214:
4208:
4207:
4187:
4174:
4173:
4153:
4147:
4146:
4126:
4115:
4114:
4094:
4085:
4084:
4064:
4053:
4052:
4032:
4023:
4022:
4002:
3949:
3947:
3945:heinrich hertz .
3925:
3916:
3914:
3900:
3894:
3892:
3877:
3871:
3870:
3850:
3844:
3843:
3828:
3822:
3821:
3801:
3792:
3791:
3771:
3678:
3669:
3663:
3662:
3660:
3658:
3648:
3639:
3614:
3613:
3599:
3593:
3592:
3590:
3588:
3578:
3569:
3550:
3549:
3539:
3533:
3532:
3530:
3528:
3512:
3475:
3474:
3454:
3441:
3440:
3420:
3414:
3413:
3393:
3384:
3383:
3363:
3357:
3356:
3346:
3337:
3336:
3334:
3332:
3316:
3307:
3306:
3304:
3302:
3288:
3279:
3278:
3276:
3274:
3258:
3252:
3251:
3231:
3225:
3224:
3203:
3157:History of radio
3118:William T. Bovie
2977:resonant circuit
2967:of a continuous
2961:Valdemar Poulsen
2915:Continuous waves
2833:
2675:
2622:
2606:
2594:
2510:
2495:
2483:
2471:
2459:
2425:
2404:magnetic blowout
2392:(see top graphs)
2372:
2358:
2342:
2318:
2306:
2286:
2274:
2234:Oliver Heaviside
2113:
2101:
2068:US Supreme Court
2049:
2029:
2017:
2001:
1986:John Stone Stone
1838:resonant circuit
1812:
1799:
1783:
1771:
1712:resonant circuit
1622:corona discharge
1557:in America, and
1498:
1478:
1458:
1438:
1365:
1353:
1337:
1321:
1309:
1274:
1095:half-wave dipole
1014:
999:millimeter waves
991:
979:
944:
924:
909:
835:electromagnetism
762:Rotary spark gap
739:motor–alternator
644:crystal detector
620:
618:
617:
612:
609:
606:
595:
594:
592:
590:
579:
561:
559:
558:
553:
538:
536:
535:
530:
511:
509:
508:
503:
393:
392:
164:, consisting of
146:electric charges
144:are radiated by
79:continuous waves
50:which generates
21:
8040:
8039:
8035:
8034:
8033:
8031:
8030:
8029:
7995:
7994:
7993:
7988:
7948:
7946:
7938:
7880:
7817:
7739:
7703:
7660:
7609:
7601:
7542:
7535:
7441:Robert Metcalfe
7296:Tim Berners-Lee
7244:
7064:Information Age
6936:
6931:
6875:
6851:
6838:
6836:
6816:
6814:
6801:
6799:Further reading
6796:
6795:
6782:
6780:
6771:
6770:
6766:
6756:
6754:
6742:
6736:
6732:
6722:
6720:
6709:
6705:
6695:
6693:
6681:
6675:
6671:
6658:
6654:
6637:
6633:
6626:
6606:
6599:
6591:
6583:
6579:
6563:
6562:
6542:
6538:
6531:
6515:
6511:
6494:
6487:
6434:
6427:
6414:
6410:
6400:
6398:
6379:
6375:
6365:
6363:
6360:New York Herald
6355:
6351:
6350:
6346:
6336:
6334:
6325:
6324:
6317:
6307:
6305:
6294:
6285:
6272:
6268:
6258:
6256:
6245:
6236:
6226:
6224:
6213:
6206:
6189:
6185:
6175:
6173:
6162:
6158:
6148:
6146:
6135:
6131:
6121:
6119:
6107:
6103:
6102:
6098:
6090:Radio Telephony
6085:
6081:
6071:
6069:
6057:
6051:
6047:
6034:
6030:
6015:
6013:
6004:
6003:
5996:
5983:
5979:
5968:
5964:
5954:
5952:
5930:
5923:
5912:
5905:
5898:
5882:
5875:
5862:
5851:
5844:
5828:
5824:
5817:
5801:
5792:
5780:
5769:
5730:(2691): 51–55.
5716:
5712:
5701:
5692:
5682:
5680:
5669:
5665:
5633:10.1.1.205.7281
5620:
5601:
5588:
5571:
5564:
5548:
5529:
5519:
5517:
5508:
5507:
5503:
5492:
5488:
5478:
5476:
5467:
5466:
5462:
5449:
5442:
5435:
5419:
5412:
5403:
5396:
5385:
5378:
5368:
5366:
5355:
5342:
5333:
5329:
5322:
5306:
5302:
5295:
5279:
5275:
5265:
5263:
5248:
5244:
5233:
5226:
5215:
5211:
5204:
5188:
5181:
5174:
5158:
5141:
5134:
5118:
5114:
5107:
5091:
5084:
5069:
5065:
5017:
5013:
5003:
5001:
4999:The Electrician
4991:
4984:
4970:
4966:
4956:
4954:
4935:
4931:
4919:
4915:
4895:
4891:
4871:
4864:
4853:
4846:
4836:
4834:
4821:
4820:
4816:
4799:
4795:
4784:
4780:
4763:
4750:
4740:
4738:
4727:
4723:
4712:
4701:
4691:
4689:
4674:
4667:
4654:
4652:
4650:
4626:
4611:
4600:
4591:
4584:
4568:
4564:
4553:
4549:
4538:
4534:
4527:
4511:
4507:
4500:
4484:
4471:
4464:
4448:
4439:
4432:
4416:
4381:
4364:
4355:
4348:
4332:
4328:
4321:
4305:
4276:
4266:
4264:
4242:
4238:
4215:
4211:
4204:
4188:
4177:
4170:
4154:
4150:
4143:
4127:
4118:
4111:
4095:
4088:
4081:
4065:
4056:
4049:
4033:
4026:
4019:
4003:
3952:
3926:
3919:
3901:
3897:
3878:
3874:
3867:
3851:
3847:
3829:
3825:
3818:
3802:
3795:
3788:
3772:
3681:
3670:
3666:
3656:
3654:
3646:
3640:
3617:
3600:
3596:
3586:
3584:
3576:
3570:
3553:
3540:
3536:
3526:
3524:
3513:
3478:
3471:
3455:
3444:
3437:
3421:
3417:
3410:
3394:
3387:
3380:
3369:College Physics
3364:
3360:
3347:
3340:
3330:
3328:
3319:
3317:
3310:
3300:
3298:
3289:
3282:
3272:
3270:
3259:
3255:
3248:
3232:
3228:
3221:
3204:
3195:
3190:
3153:
3090:radio operators
3086:
3077:broadcast radio
3050:Edwin Armstrong
3028:
3002:current in the
3000:radio frequency
2917:
2869:Marconi Company
2831:
2697:
2692:
2687:
2652:
2650:The "spark" era
2647:
2646:
2645:
2644:
2628:
2627:
2626:
2623:
2615:
2614:
2607:
2599:
2598:
2595:
2563:continuous wave
2559:
2514:
2511:
2502:
2496:
2487:
2484:
2475:
2472:
2463:
2460:
2443:
2423:
2380:
2379:
2378:
2377:
2376:
2373:
2364:
2363:
2362:
2359:
2346:
2343:
2334:
2319:
2310:
2307:
2298:
2287:
2278:
2275:
2266:
2230:Arthur Kennelly
2121:
2120:
2119:
2118:
2117:
2114:
2106:
2105:
2102:
2091:
2053:
2050:
2041:
2030:
2021:
2018:
2009:
2002:
1886:primary winding
1878:coupled circuit
1834:
1827:
1813:
1804:
1800:
1791:
1784:
1775:
1772:
1700:William Crookes
1679:
1661:radio receivers
1606:electric charge
1579:
1547:Eugène Ducretet
1543:Alexander Popov
1519:English Channel
1512:of the British
1506:
1505:
1504:
1503:
1502:
1499:
1491:
1490:
1479:
1471:
1470:
1459:
1451:
1450:
1439:
1389:
1388:
1387:
1386:
1385:
1366:
1358:
1357:
1354:
1346:
1345:
1338:
1330:
1329:
1322:
1314:
1313:
1310:
1301:
1300:
1284:radiotelegraphy
1275:
1272:
1265:
1022:
1015:
1006:
1003:(in box, right)
992:
983:
980:
971:
959:, auto battery
945:
936:
925:
916:
910:
874:
851:magnetic fields
791:
781:
764:
755:
726:
705:
687:
599:
593:
583:
578:
570:
567:
566:
547:
544:
543:
524:
521:
520:
497:
494:
493:
460:; a radio wave.
429:, reducing its
408:
407:
406:
405:
404:
394:
387:
384:
357:
355:Operation cycle
298:primary winding
250:radio frequency
225:A high-voltage
192:radio frequency
139:
95:radiotelegraphy
54:by means of an
28:
23:
22:
15:
12:
11:
5:
8038:
8028:
8027:
8022:
8017:
8012:
8007:
7990:
7989:
7987:
7986:
7976:
7966:
7956:
7943:
7940:
7939:
7937:
7936:
7929:
7924:
7919:
7914:
7909:
7908:
7907:
7902:
7894:
7888:
7886:
7882:
7881:
7879:
7878:
7873:
7868:
7863:
7858:
7853:
7848:
7843:
7838:
7833:
7827:
7825:
7819:
7818:
7816:
7815:
7810:
7805:
7800:
7795:
7790:
7785:
7780:
7775:
7770:
7765:
7760:
7755:
7749:
7747:
7741:
7740:
7738:
7737:
7732:
7727:
7722:
7717:
7711:
7709:
7705:
7704:
7702:
7701:
7696:
7691:
7686:
7681:
7676:
7674:Space-division
7670:
7668:
7662:
7661:
7659:
7658:
7653:
7652:
7651:
7646:
7636:
7635:
7634:
7624:
7619:
7613:
7611:
7603:
7602:
7600:
7599:
7598:
7597:
7587:
7586:
7585:
7575:
7570:
7565:
7564:
7563:
7553:
7547:
7545:
7537:
7536:
7534:
7533:
7528:
7523:
7518:
7513:
7511:Camille Tissot
7508:
7503:
7498:
7493:
7488:
7486:Claude Shannon
7483:
7478:
7476:Tivadar Puskás
7473:
7468:
7463:
7458:
7453:
7448:
7446:Antonio Meucci
7443:
7438:
7433:
7428:
7423:
7418:
7416:Charles K. Kao
7413:
7408:
7403:
7398:
7393:
7391:Harold Hopkins
7388:
7383:
7378:
7373:
7368:
7363:
7358:
7353:
7348:
7343:
7338:
7333:
7328:
7323:
7318:
7313:
7308:
7303:
7298:
7293:
7291:Emile Berliner
7288:
7283:
7278:
7273:
7268:
7263:
7258:
7252:
7250:
7246:
7245:
7243:
7242:
7237:
7232:
7230:Videotelephony
7227:
7222:
7221:
7220:
7215:
7205:
7198:
7193:
7187:
7182:
7177:
7172:
7167:
7166:
7165:
7160:
7155:
7145:
7144:
7143:
7133:
7128:
7126:Radiotelephone
7123:
7118:
7113:
7108:
7103:
7098:
7093:
7092:
7091:
7081:
7076:
7071:
7066:
7061:
7056:
7051:
7046:
7041:
7036:
7031:
7030:
7029:
7024:
7019:
7014:
7012:Internet video
7004:
7003:
7002:
6997:
6992:
6987:
6977:
6972:
6967:
6962:
6957:
6952:
6946:
6944:
6938:
6937:
6930:
6929:
6922:
6915:
6907:
6901:
6900:
6895:
6890:
6885:
6873:
6867:
6862:
6857:
6850:
6849:External links
6847:
6846:
6845:
6823:
6800:
6797:
6794:
6793:
6779:on 16 May 2006
6764:
6730:
6703:
6669:
6652:
6631:
6625:978-1365493225
6624:
6597:
6577:
6536:
6530:978-0198021780
6529:
6509:
6485:
6425:
6408:
6373:
6344:
6315:
6283:
6266:
6234:
6204:
6183:
6156:
6129:
6112:Wireless World
6096:
6079:
6062:Wireless World
6045:
6028:
5994:
5977:
5962:
5921:
5903:
5897:978-0852967928
5896:
5873:
5849:
5843:978-3642295515
5842:
5822:
5816:978-0863413278
5815:
5790:
5767:
5710:
5690:
5663:
5599:
5569:
5563:978-0852967928
5562:
5527:
5501:
5486:
5460:
5440:
5434:978-0080963907
5433:
5410:
5394:
5376:
5340:
5327:
5320:
5300:
5294:978-0786426621
5293:
5273:
5242:
5224:
5209:
5203:978-0313331671
5202:
5179:
5173:978-0471697398
5172:
5139:
5133:978-0760710050
5132:
5112:
5106:978-1136993756
5105:
5082:
5063:
5036:(8): 355–357.
5011:
4982:
4964:
4929:
4913:
4889:
4862:
4844:
4814:
4793:
4778:
4748:
4721:
4699:
4665:
4648:
4609:
4589:
4583:978-0863413278
4582:
4562:
4547:
4532:
4526:978-0191533457
4525:
4505:
4499:978-0470871188
4498:
4469:
4463:978-0471205050
4462:
4437:
4431:978-1400857883
4430:
4379:
4353:
4347:978-0521835398
4346:
4326:
4320:978-0852967928
4319:
4274:
4236:
4209:
4203:978-1615303007
4202:
4175:
4169:978-0786748549
4168:
4148:
4142:978-0786426621
4141:
4116:
4109:
4086:
4080:978-0521835398
4079:
4054:
4048:978-9401588553
4047:
4024:
4017:
3950:
3917:
3895:
3872:
3866:978-0387951508
3865:
3845:
3823:
3817:978-0387951508
3816:
3793:
3787:978-0471783015
3786:
3679:
3664:
3615:
3594:
3551:
3534:
3476:
3470:978-1400854608
3469:
3442:
3436:978-0387951508
3435:
3415:
3409:978-1316785164
3408:
3385:
3379:978-0495386933
3378:
3358:
3338:
3308:
3280:
3253:
3247:978-0122004001
3246:
3226:
3220:978-1135455514
3219:
3192:
3191:
3189:
3186:
3185:
3184:
3179:
3174:
3169:
3164:
3159:
3152:
3149:
3129:remote control
3122:electrosurgery
3114:electric shock
3085:
3082:
3027:
3024:
3008:
3007:
2980:
2916:
2913:
2877:British Empire
2788:ignition coils
2780:radio amateurs
2770:
2769:
2766:
2763:
2760:
2756:
2755:
2752:
2749:
2746:
2742:
2741:
2738:
2735:
2732:
2728:
2727:
2724:
2721:
2720:500, 660, 1000
2718:
2714:
2713:
2710:
2707:
2704:
2700:
2699:
2694:
2689:
2684:
2680:
2679:
2651:
2648:
2630:
2629:
2624:
2617:
2616:
2613:one foot thick
2608:
2601:
2600:
2596:
2589:
2588:
2587:
2586:
2585:
2558:
2555:
2542:
2541:
2526:
2523:Nonsynchronous
2516:
2515:
2512:
2505:
2503:
2497:
2490:
2488:
2485:
2478:
2476:
2473:
2466:
2464:
2461:
2454:
2442:
2439:
2374:
2367:
2366:
2365:
2360:
2353:
2352:
2351:
2350:
2349:
2348:
2347:
2344:
2337:
2335:
2320:
2313:
2311:
2308:
2301:
2299:
2293:quenched gap,
2288:
2281:
2279:
2276:
2269:
2265:
2262:
2115:
2108:
2107:
2103:
2096:
2095:
2094:
2093:
2092:
2090:
2087:
2055:
2054:
2051:
2044:
2042:
2031:
2024:
2022:
2019:
2012:
2010:
2003:
1996:
1967:wireless power
1833:
1830:
1829:
1828:
1814:
1807:
1805:
1801:
1794:
1792:
1788:(center right)
1785:
1778:
1776:
1773:
1766:
1678:
1675:
1653:radio spectrum
1578:
1575:
1567:Georg von Arco
1510:William Preece
1500:
1493:
1492:
1480:
1473:
1472:
1460:
1453:
1452:
1440:
1433:
1432:
1431:
1430:
1429:
1367:
1360:
1359:
1355:
1348:
1347:
1339:
1332:
1331:
1323:
1316:
1315:
1311:
1304:
1303:
1302:
1298:
1297:
1296:
1295:
1270:
1264:
1261:
1218:standing waves
1083:standing waves
1062:induction coil
1044:dipole antenna
1024:
1023:
1016:
1009:
1007:
993:
986:
984:
981:
974:
972:
946:
939:
937:
935:induction coil
926:
919:
917:
911:
904:
878:Heinrich Hertz
873:
870:
780:
777:
763:
760:
754:
751:
743:electric motor
725:
724:AC transformer
722:
709:induction coil
704:
703:Induction coil
701:
686:
683:
642:, such as the
622:
621:
605:
602:
598:
589:
586:
582:
577:
574:
551:
528:
501:
481:and decreases
471:
470:
461:
454:electric field
450:magnetic field
446:
438:
427:electric spark
425:, starting an
415:
395:
385:
380:
379:
378:
377:
376:
362:radio receiver
356:
353:
352:
351:
341:
330:
319:
318:
317:
302:magnetic field
280:
242:
239:induction coil
177:electric spark
148:when they are
138:
135:
81:used to carry
68:Heinrich Hertz
56:electric spark
26:
9:
6:
4:
3:
2:
8037:
8026:
8023:
8021:
8018:
8016:
8015:Electric arcs
8013:
8011:
8008:
8006:
8003:
8002:
8000:
7985:
7977:
7975:
7967:
7965:
7957:
7955:
7945:
7944:
7941:
7934:
7930:
7928:
7925:
7923:
7920:
7918:
7915:
7913:
7910:
7906:
7903:
7901:
7898:
7897:
7895:
7893:
7890:
7889:
7887:
7883:
7877:
7874:
7872:
7869:
7867:
7864:
7862:
7859:
7857:
7854:
7852:
7849:
7847:
7844:
7842:
7839:
7837:
7834:
7832:
7829:
7828:
7826:
7824:
7820:
7814:
7811:
7809:
7806:
7804:
7801:
7799:
7796:
7794:
7791:
7789:
7786:
7784:
7781:
7779:
7776:
7774:
7771:
7769:
7766:
7764:
7761:
7759:
7756:
7754:
7751:
7750:
7748:
7746:
7742:
7736:
7733:
7731:
7728:
7726:
7723:
7721:
7718:
7716:
7713:
7712:
7710:
7706:
7700:
7699:Code-division
7697:
7695:
7692:
7690:
7687:
7685:
7684:Time-division
7682:
7680:
7677:
7675:
7672:
7671:
7669:
7667:
7663:
7657:
7654:
7650:
7647:
7645:
7642:
7641:
7640:
7637:
7633:
7630:
7629:
7628:
7625:
7623:
7620:
7618:
7615:
7614:
7612:
7610:and switching
7608:
7604:
7596:
7593:
7592:
7591:
7588:
7584:
7581:
7580:
7579:
7576:
7574:
7571:
7569:
7566:
7562:
7561:optical fiber
7559:
7558:
7557:
7554:
7552:
7551:Coaxial cable
7549:
7548:
7546:
7544:
7538:
7532:
7529:
7527:
7524:
7522:
7519:
7517:
7514:
7512:
7509:
7507:
7504:
7502:
7499:
7497:
7494:
7492:
7489:
7487:
7484:
7482:
7479:
7477:
7474:
7472:
7469:
7467:
7466:Radia Perlman
7464:
7462:
7459:
7457:
7454:
7452:
7449:
7447:
7444:
7442:
7439:
7437:
7434:
7432:
7429:
7427:
7424:
7422:
7419:
7417:
7414:
7412:
7409:
7407:
7404:
7402:
7399:
7397:
7394:
7392:
7389:
7387:
7384:
7382:
7379:
7377:
7374:
7372:
7369:
7367:
7364:
7362:
7359:
7357:
7356:Lee de Forest
7354:
7352:
7351:Thomas Edison
7349:
7347:
7344:
7342:
7341:Donald Davies
7339:
7337:
7334:
7332:
7329:
7327:
7326:Claude Chappe
7324:
7322:
7319:
7317:
7314:
7312:
7309:
7307:
7304:
7302:
7299:
7297:
7294:
7292:
7289:
7287:
7284:
7282:
7279:
7277:
7274:
7272:
7269:
7267:
7264:
7262:
7259:
7257:
7254:
7253:
7251:
7247:
7241:
7238:
7236:
7233:
7231:
7228:
7226:
7223:
7219:
7216:
7214:
7211:
7210:
7209:
7206:
7204:
7203:
7199:
7197:
7194:
7191:
7188:
7186:
7183:
7181:
7178:
7176:
7173:
7171:
7170:Smoke signals
7168:
7164:
7161:
7159:
7156:
7154:
7151:
7150:
7149:
7148:Semiconductor
7146:
7142:
7139:
7138:
7137:
7134:
7132:
7129:
7127:
7124:
7122:
7119:
7117:
7114:
7112:
7109:
7107:
7104:
7102:
7099:
7097:
7094:
7090:
7087:
7086:
7085:
7082:
7080:
7077:
7075:
7072:
7070:
7067:
7065:
7062:
7060:
7057:
7055:
7052:
7050:
7047:
7045:
7042:
7040:
7037:
7035:
7032:
7028:
7025:
7023:
7020:
7018:
7015:
7013:
7010:
7009:
7008:
7007:Digital media
7005:
7001:
6998:
6996:
6993:
6991:
6988:
6986:
6983:
6982:
6981:
6978:
6976:
6973:
6971:
6968:
6966:
6963:
6961:
6958:
6956:
6953:
6951:
6948:
6947:
6945:
6943:
6939:
6935:
6928:
6923:
6921:
6916:
6914:
6909:
6908:
6905:
6899:
6896:
6894:
6891:
6889:
6886:
6882:
6878:
6874:
6871:
6868:
6866:
6863:
6861:
6858:
6856:
6853:
6852:
6839:September 14,
6834:
6833:
6828:
6824:
6817:September 12,
6812:
6808:
6803:
6802:
6790:
6778:
6774:
6768:
6752:
6748:
6741:
6734:
6718:
6714:
6707:
6691:
6687:
6680:
6673:
6665:
6664:
6656:
6648:
6644:
6643:
6635:
6627:
6621:
6617:
6613:
6612:
6604:
6602:
6590:
6589:
6581:
6573:
6567:
6559:
6555:
6554:
6547:
6540:
6532:
6526:
6522:
6521:
6513:
6505:
6501:
6500:
6492:
6490:
6481:
6477:
6472:
6467:
6463:
6459:
6455:
6451:
6447:
6443:
6439:
6432:
6430:
6421:
6420:
6412:
6397:on 2002-10-20
6396:
6392:
6388:
6384:
6377:
6361:
6354:
6348:
6332:
6328:
6322:
6320:
6303:
6299:
6292:
6290:
6288:
6279:
6278:
6270:
6254:
6250:
6243:
6241:
6239:
6222:
6218:
6211:
6209:
6200:
6196:
6195:
6187:
6171:
6167:
6160:
6144:
6140:
6133:
6117:
6113:
6106:
6100:
6092:
6091:
6083:
6068:(78): 310–316
6067:
6063:
6056:
6049:
6041:
6040:
6032:
6025:
6011:
6007:
6001:
5999:
5990:
5989:
5981:
5974:
5973:
5966:
5951:
5947:
5944:(1746): 390.
5943:
5939:
5935:
5928:
5926:
5919:
5917:
5910:
5908:
5899:
5893:
5889:
5888:
5880:
5878:
5869:
5868:
5860:
5858:
5856:
5854:
5845:
5839:
5835:
5834:
5826:
5818:
5812:
5808:
5807:
5799:
5797:
5795:
5787:
5785:
5778:
5776:
5774:
5772:
5763:
5759:
5754:
5749:
5745:
5741:
5737:
5733:
5729:
5725:
5721:
5714:
5708:
5706:
5699:
5697:
5695:
5678:
5674:
5667:
5659:
5655:
5651:
5647:
5643:
5639:
5634:
5629:
5625:
5618:
5616:
5614:
5612:
5610:
5608:
5606:
5604:
5595:
5594:
5586:
5584:
5582:
5580:
5578:
5576:
5574:
5565:
5559:
5555:
5554:
5546:
5544:
5542:
5540:
5538:
5536:
5534:
5532:
5515:
5511:
5505:
5499:
5497:
5494:Morse (1925)
5490:
5474:
5470:
5464:
5457:
5453:
5447:
5445:
5436:
5430:
5426:
5425:
5417:
5415:
5407:
5401:
5399:
5391:
5390:
5383:
5381:
5364:
5360:
5353:
5351:
5349:
5347:
5345:
5337:
5331:
5323:
5317:
5313:
5312:
5304:
5296:
5290:
5286:
5285:
5277:
5261:
5257:
5253:
5246:
5239:
5238:
5231:
5229:
5222:
5220:
5213:
5205:
5199:
5195:
5194:
5186:
5184:
5175:
5169:
5165:
5164:
5156:
5154:
5152:
5150:
5148:
5146:
5144:
5135:
5129:
5125:
5124:
5116:
5108:
5102:
5098:
5097:
5089:
5087:
5079:
5078:
5073:
5067:
5059:
5055:
5051:
5047:
5043:
5039:
5035:
5031:
5025:
5021:
5015:
5000:
4996:
4989:
4987:
4978:
4977:
4968:
4952:
4948:
4944:
4940:
4933:
4927:
4925:
4917:
4910:
4906:
4902:
4901:
4893:
4886:
4882:
4878:
4877:
4869:
4867:
4859:
4858:
4851:
4849:
4832:
4828:
4824:
4818:
4810:
4806:
4805:
4797:
4791:
4789:
4782:
4774:
4770:
4769:
4761:
4759:
4757:
4755:
4753:
4736:
4732:
4725:
4718:
4717:
4710:
4708:
4706:
4704:
4687:
4683:
4679:
4672:
4670:
4663:
4651:
4649:0-85296-649-0
4645:
4641:
4637:
4633:
4632:
4624:
4622:
4620:
4618:
4616:
4614:
4606:
4605:
4598:
4596:
4594:
4585:
4579:
4575:
4574:
4566:
4560:
4558:
4551:
4545:
4543:
4540:Morse (1925)
4536:
4528:
4522:
4518:
4517:
4509:
4501:
4495:
4491:
4490:
4482:
4480:
4478:
4476:
4474:
4465:
4459:
4455:
4454:
4446:
4444:
4442:
4433:
4427:
4423:
4422:
4414:
4412:
4410:
4408:
4406:
4404:
4402:
4400:
4398:
4396:
4394:
4392:
4390:
4388:
4386:
4384:
4376:
4375:
4370:
4369:
4362:
4360:
4358:
4349:
4343:
4339:
4338:
4330:
4322:
4316:
4312:
4311:
4303:
4301:
4299:
4297:
4295:
4293:
4291:
4289:
4287:
4285:
4283:
4281:
4279:
4263:
4259:
4255:
4251:
4247:
4240:
4231:
4227:
4226:
4219:
4213:
4205:
4199:
4195:
4194:
4186:
4184:
4182:
4180:
4171:
4165:
4161:
4160:
4152:
4144:
4138:
4134:
4133:
4125:
4123:
4121:
4112:
4110:9780405060526
4106:
4102:
4101:
4093:
4091:
4082:
4076:
4072:
4071:
4063:
4061:
4059:
4050:
4044:
4040:
4039:
4031:
4029:
4020:
4018:9780262514194
4014:
4011:. MIT Press.
4010:
4009:
4001:
3999:
3997:
3995:
3993:
3991:
3989:
3987:
3985:
3983:
3981:
3979:
3977:
3975:
3973:
3971:
3969:
3967:
3965:
3963:
3961:
3959:
3957:
3955:
3946:
3942:
3938:
3937:
3930:
3924:
3922:
3912:
3908:
3907:
3899:
3890:
3889:
3882:
3876:
3868:
3862:
3858:
3857:
3849:
3841:
3840:
3833:
3827:
3819:
3813:
3809:
3808:
3800:
3798:
3789:
3783:
3779:
3778:
3770:
3768:
3766:
3764:
3762:
3760:
3758:
3756:
3754:
3752:
3750:
3748:
3746:
3744:
3742:
3740:
3738:
3736:
3734:
3732:
3730:
3728:
3726:
3724:
3722:
3720:
3718:
3716:
3714:
3712:
3710:
3708:
3706:
3704:
3702:
3700:
3698:
3696:
3694:
3692:
3690:
3688:
3686:
3684:
3676:
3675:
3668:
3652:
3645:
3638:
3636:
3634:
3632:
3630:
3628:
3626:
3624:
3622:
3620:
3611:
3607:
3606:
3598:
3582:
3575:
3568:
3566:
3564:
3562:
3560:
3558:
3556:
3547:
3546:
3538:
3522:
3518:
3517:"Spark Radio"
3511:
3509:
3507:
3505:
3503:
3501:
3499:
3497:
3495:
3493:
3491:
3489:
3487:
3485:
3483:
3481:
3472:
3466:
3462:
3461:
3453:
3451:
3449:
3447:
3438:
3432:
3428:
3427:
3419:
3411:
3405:
3401:
3400:
3392:
3390:
3381:
3375:
3371:
3370:
3362:
3354:
3353:
3345:
3343:
3326:
3322:
3315:
3313:
3301:September 14,
3296:
3295:
3287:
3285:
3268:
3264:
3257:
3249:
3243:
3239:
3238:
3230:
3222:
3216:
3212:
3211:
3202:
3200:
3198:
3193:
3183:
3182:Crystal radio
3180:
3178:
3175:
3173:
3172:Antique radio
3170:
3168:
3167:Amateur radio
3165:
3163:
3160:
3158:
3155:
3154:
3148:
3146:
3142:
3137:
3135:
3130:
3125:
3123:
3119:
3115:
3110:
3106:
3102:
3097:
3095:
3091:
3081:
3078:
3073:
3070:
3066:
3065:Lee de Forest
3062:
3059:
3055:
3051:
3047:
3044:
3041:
3032:
3023:
3021:
3017:
3013:
3005:
3001:
2997:
2993:
2989:
2985:
2981:
2978:
2974:
2970:
2966:
2962:
2958:
2957:arc converter
2954:
2953:
2952:
2949:
2946:
2942:
2937:
2934:
2929:
2926:
2922:
2912:
2910:
2906:
2902:
2898:
2894:
2890:
2886:
2882:
2878:
2874:
2870:
2866:
2862:
2858:
2849:
2845:
2840:
2836:
2830:
2826:
2825:
2819:
2818:
2812:
2808:
2803:
2802:
2795:
2793:
2789:
2785:
2781:
2777:
2767:
2765:20,000 - 1600
2764:
2761:
2758:
2757:
2753:
2750:
2747:
2744:
2743:
2739:
2736:
2733:
2730:
2729:
2725:
2723:600, 450, 300
2722:
2719:
2716:
2715:
2711:
2708:
2705:
2701:
2696:Typical power
2695:
2690:
2685:
2682:
2681:
2676:
2673:
2671:
2670:
2664:
2663:
2658:
2643:transmitters.
2642:
2638:
2634:
2621:
2612:
2605:
2593:
2584:
2582:
2577:
2572:
2571:superposition
2568:
2564:
2554:
2551:
2547:
2539:
2534:
2530:
2527:
2524:
2521:
2520:
2519:
2509:
2504:
2500:
2494:
2489:
2482:
2477:
2470:
2465:
2458:
2453:
2452:
2451:
2448:
2438:
2436:
2431:
2429:
2420:
2416:
2413:, called the
2412:
2407:
2405:
2401:
2400:Elihu Thomson
2395:
2393:
2390:
2386:
2371:
2357:
2341:
2336:
2332:
2328:
2324:
2317:
2312:
2305:
2300:
2296:
2292:
2285:
2280:
2273:
2268:
2267:
2261:
2259:
2253:
2251:
2247:
2243:
2239:
2235:
2231:
2225:
2223:
2219:
2215:
2211:
2207:
2204:
2200:
2196:
2192:
2188:
2184:
2180:
2175:
2173:
2169:
2165:
2161:
2158:
2154:
2150:
2149:(see circuit)
2146:
2142:
2133:
2125:
2112:
2100:
2086:
2084:
2079:
2077:
2071:
2069:
2064:
2061:
2048:
2043:
2039:
2036:and receiver
2035:
2028:
2023:
2016:
2011:
2007:
2000:
1995:
1994:
1993:
1991:
1987:
1983:
1979:
1974:
1972:
1971:communication
1968:
1964:
1960:
1959:Geissler tube
1956:
1955:
1950:
1946:
1942:
1938:
1933:
1931:
1927:
1923:
1919:
1915:
1911:
1907:
1903:
1899:
1895:
1891:
1887:
1883:
1879:
1875:
1871:
1867:
1863:
1855:
1851:
1846:
1842:
1839:
1826:
1822:
1818:
1811:
1806:
1798:
1793:
1789:
1782:
1777:
1770:
1765:
1764:
1763:
1761:
1760:loading coils
1756:
1752:
1747:
1745:
1741:
1737:
1733:
1729:
1724:
1722:
1719:"tuning" its
1717:
1713:
1709:
1706:(then called
1705:
1701:
1692:
1689:and receiver
1688:
1683:
1674:
1671:
1670:G. W. Pickard
1667:
1666:Lee de Forest
1662:
1658:
1654:
1650:
1646:
1642:
1638:
1629:
1625:
1623:
1619:
1615:
1611:
1607:
1603:
1599:
1594:
1592:
1583:
1577:Disadvantages
1574:
1572:
1568:
1564:
1560:
1556:
1555:Lee de Forest
1552:
1548:
1544:
1540:
1536:
1532:
1527:
1524:
1520:
1515:
1511:
1497:
1488:
1484:
1477:
1468:
1465:and receiver
1464:
1457:
1448:
1444:
1437:
1428:
1426:
1422:
1418:
1414:
1410:
1406:
1402:
1399:
1395:
1383:
1379:
1375:
1371:
1364:
1352:
1343:
1336:
1327:
1320:
1308:
1294:
1292:
1288:
1285:
1281:
1269:
1260:
1258:
1253:
1251:
1247:
1243:
1242:Augusto Righi
1239:
1235:
1231:
1227:
1223:
1219:
1215:
1211:
1207:
1203:
1199:
1195:
1191:
1187:
1183:
1179:
1175:
1171:
1167:
1163:
1158:
1156:
1152:
1148:
1144:
1140:
1139:Augusto Righi
1136:
1132:
1128:
1127:Lord Rayleigh
1124:
1115:
1110:
1106:
1104:
1100:
1096:
1092:
1088:
1084:
1079:
1075:
1071:
1067:
1063:
1059:
1056:
1052:
1049:
1045:
1037:
1033:
1028:
1020:
1013:
1008:
1004:
1000:
996:
990:
985:
978:
973:
969:
966:
965:telegraph key
962:
958:
954:
950:
943:
938:
934:
930:
923:
918:
915:
908:
903:
902:
901:
899:
895:
891:
887:
884:predicted by
883:
879:
869:
866:
864:
860:
856:
852:
848:
844:
841:, now called
840:
836:
831:
829:
825:
821:
816:
815:Thomas Edison
812:
811:Mahlon Loomis
808:
804:
799:
794:
790:
786:
776:
773:
769:
759:
750:
748:
744:
740:
736:
731:
721:
719:
714:
710:
700:
697:
692:
682:
680:
676:
672:
671:telegraph key
668:
663:
661:
657:
653:
649:
648:Fleming valve
645:
641:
638:
635:
631:
627:
603:
600:
596:
587:
584:
580:
575:
572:
565:
564:
563:
562:of the coil:
549:
542:
526:
519:
515:
499:
492:
488:
484:
483:exponentially
480:
476:
467:
462:
459:
455:
451:
447:
443:
439:
436:
432:
428:
424:
420:
416:
412:
411:
402:
398:
383:
374:
369:
365:
363:
350:
346:
345:telegraph key
342:
339:
335:
331:
328:
324:
320:
315:
311:
307:
303:
299:
295:
291:
287:
286:
281:
278:
274:
273:
271:
267:
263:
259:
255:
251:
247:
243:
240:
236:
232:
228:
224:
223:
222:
214:
210:
208:
204:
199:
197:
193:
190:
186:
182:
178:
174:
169:
167:
163:
159:
155:
151:
147:
143:
134:
132:
128:
123:
119:
118:
111:
106:
104:
100:
99:telegraph key
96:
92:
88:
84:
80:
76:
71:
69:
65:
61:
57:
53:
49:
45:
37:
32:
19:
7666:Multiplexing
7541:Transmission
7506:Nikola Tesla
7496:Henry Sutton
7451:Samuel Morse
7381:Robert Hooke
7346:Amos Dolbear
7281:John Bardeen
7200:
7180:Telautograph
7084:Mobile phone
7039:Edholm's law
7022:social media
6955:Broadcasting
6881:the original
6837:. Retrieved
6831:
6815:. Retrieved
6810:
6788:
6781:. Retrieved
6777:the original
6767:
6757:November 11,
6755:. Retrieved
6750:
6746:
6733:
6721:. Retrieved
6716:
6706:
6694:. Retrieved
6689:
6685:
6672:
6662:
6655:
6641:
6634:
6610:
6587:
6580:
6552:
6545:
6539:
6519:
6512:
6498:
6445:
6441:
6418:
6411:
6399:. Retrieved
6395:the original
6390:
6386:
6376:
6364:. Retrieved
6359:
6347:
6335:. Retrieved
6330:
6306:. Retrieved
6301:
6276:
6269:
6257:. Retrieved
6252:
6225:. Retrieved
6220:
6193:
6186:
6174:. Retrieved
6169:
6159:
6147:. Retrieved
6142:
6132:
6120:. Retrieved
6115:
6111:
6099:
6089:
6082:
6070:. Retrieved
6065:
6061:
6048:
6038:
6031:
6023:
6022:included in
6014:. Retrieved
6009:
5987:
5980:
5970:
5965:
5953:. Retrieved
5941:
5937:
5915:
5886:
5866:
5832:
5825:
5805:
5786:, p. 271-272
5783:
5727:
5723:
5713:
5704:
5681:. Retrieved
5677:The Guardian
5676:
5666:
5623:
5592:
5552:
5518:. Retrieved
5513:
5504:
5495:
5489:
5477:. Retrieved
5472:
5463:
5423:
5388:
5367:. Retrieved
5362:
5330:
5310:
5303:
5283:
5276:
5264:. Retrieved
5259:
5255:
5245:
5235:
5218:
5212:
5192:
5162:
5122:
5115:
5095:
5080:, p. 294-373
5075:
5071:
5070:Tesla, N., "
5066:
5033:
5029:
5023:
5019:
5014:
5002:. Retrieved
4998:
4975:
4967:
4955:. Retrieved
4951:the original
4946:
4942:
4932:
4926:, p. 111-116
4923:
4916:
4908:
4899:
4892:
4884:
4875:
4855:
4835:. Retrieved
4830:
4826:
4817:
4803:
4796:
4787:
4781:
4767:
4739:. Retrieved
4734:
4724:
4715:
4690:. Retrieved
4688:(3): 179–188
4685:
4681:
4653:. Retrieved
4630:
4602:
4572:
4565:
4559:, p. 212-215
4556:
4550:
4541:
4535:
4515:
4508:
4488:
4452:
4420:
4372:
4366:
4336:
4329:
4309:
4265:. Retrieved
4256:(5): 55–88.
4253:
4249:
4239:
4224:
4217:
4212:
4192:
4158:
4151:
4131:
4099:
4069:
4037:
4007:
3944:
3935:
3928:
3905:
3898:
3887:
3880:
3875:
3855:
3848:
3838:
3831:
3826:
3806:
3776:
3672:
3667:
3655:. Retrieved
3650:
3604:
3597:
3585:. Retrieved
3580:
3544:
3537:
3525:. Retrieved
3520:
3459:
3425:
3418:
3398:
3368:
3361:
3351:
3329:. Retrieved
3324:
3299:. Retrieved
3293:
3271:. Retrieved
3266:
3256:
3236:
3229:
3209:
3138:
3126:
3098:
3093:
3087:
3074:
3037:
3026:Obsolescence
3016:carrier wave
3009:
2969:electric arc
2950:
2945:audio signal
2930:
2921:damped waves
2918:
2909:loading coil
2853:
2828:
2823:
2816:
2810:
2806:
2800:
2796:
2792:Ford Model T
2773:
2688:(kilohertz)
2668:
2660:
2656:
2653:
2560:
2545:
2543:
2528:
2522:
2517:
2444:
2432:
2427:
2418:
2414:
2408:
2396:
2391:
2387:, producing
2381:
2330:
2326:
2322:
2294:
2290:
2254:
2226:
2199:Newfoundland
2187:Nikola Tesla
2176:
2172:(S2, C2, T3)
2171:
2167:
2164:(S1, C1, T2)
2163:
2159:
2152:
2148:
2138:
2080:
2075:
2072:
2062:
2060:loading coil
2056:
2037:
2033:
2005:
1978:Oliver Lodge
1975:
1970:
1962:
1952:
1937:Nikola Tesla
1934:
1925:
1917:
1909:
1905:
1901:
1897:
1893:
1889:
1881:
1877:
1873:
1869:
1859:
1853:
1849:
1835:
1824:
1820:
1787:
1748:
1740:Oliver Lodge
1725:
1707:
1696:
1690:
1686:
1685:Transmitter
1634:
1595:
1588:
1539:marine radio
1528:
1507:
1486:
1482:
1466:
1462:
1446:
1442:
1398:quarter-wave
1390:
1381:
1377:
1373:
1369:
1341:
1325:
1287:transmitters
1277:
1267:
1254:
1234:interference
1230:polarization
1186:paraffin wax
1174:quasioptical
1159:
1143:Oliver Lodge
1120:
1113:
1103:Oliver Lodge
1098:
1077:
1065:
1057:
1050:
1041:
1031:
1019:Oliver Lodge
1002:
967:
960:
956:
952:
951:, spark gap
948:
932:
928:
913:
875:
867:
863:loop antenna
832:
795:
792:
767:
765:
756:
727:
706:
695:
690:
688:
664:
623:
472:
358:
293:
289:
283:
254:oscillations
244:One or more
220:
200:
194:oscillating
170:
140:
116:
107:
75:damped waves
72:
43:
41:
7866:NPL network
7578:Radio waves
7516:Alfred Vail
7426:Hedy Lamarr
7411:Dawon Kahng
7371:Elisha Gray
7331:Yogen Dalal
7256:Nasir Ahmed
7190:Teleprinter
7054:Heliographs
6747:Electronics
5683:8 September
4267:January 30,
3061:vacuum tube
3040:vacuum tube
2861:World War I
2824:Californian
2748:187.5 - 333
2734:187.5 - 500
2712:0.25 - 0.5
2698:range (kW)
2529:Synchronous
2258:radio noise
1882:two circuit
1868:(called an
1864:, making a
1856:and ground.
1751:tuning fork
1732:Leyden jars
1649:radio noise
1610:capacitance
1563:Adolf Slaby
1549:in France,
1545:in Russia,
1417:ground wave
1226:diffraction
1162:light waves
1087:damped wave
1055:capacitance
1032:(not shown)
890:radio waves
730:transformer
713:interrupter
630:demodulated
518:capacitance
487:damped wave
338:radio waves
252:electrical
227:transformer
207:oscillatory
173:capacitance
154:Radio waves
150:accelerated
129:, creating
52:radio waves
8025:Telegraphy
7999:Categories
7912:Antarctica
7871:Toasternet
7793:Television
7276:Paul Baran
7208:Television
7192:(teletype)
7185:Telegraphy
7163:transistor
7141:Phryctoria
7111:Photophone
7089:Smartphone
7079:Mass media
6692:(5): 43–46
6366:5 February
6337:5 February
5955:5 December
5918:, p. 60-63
5707:, p. 55-59
5266:3 December
5221:, p. 96-97
4957:August 19,
4719:, p. 34-36
4544:, p. 24-26
3677:, p. 38-43
3657:5 February
3188:References
3136:receiver.
3116:. In 1926
3105:Oudin coil
3101:Tesla coil
2996:alternator
2936:sinusoidal
2933:continuous
2881:Telefunken
2762:15 - 187.5
2751:1600 - 900
2737:1600 - 600
2691:Wavelength
2435:Telefunken
2157:alternator
1954:Tesla coil
1922:Leyden jar
1728:capacitors
1657:interfered
1571:Telefunken
1523:Morse code
1250:microwaves
1222:refraction
1166:wavelength
898:Leyden jar
747:alternator
691:spark rate
675:Morse code
634:rectifying
541:inductance
475:sinusoidal
442:inductance
431:resistance
397:Morse code
349:Morse code
262:Leyden jar
203:inductance
187:to excite
103:Morse code
7896:Americas
7885:Locations
7856:Internet2
7617:Bandwidth
7321:Vint Cerf
7218:streaming
7196:Telephone
7136:Semaphore
7027:streaming
6783:6 January
6566:cite book
6176:2 October
6122:19 August
6072:19 August
5658:218471926
5650:0537-9989
5628:CiteSeerX
5520:March 14,
5050:0095-9197
3109:diathermy
3069:modulated
2941:modulated
2817:Carpathia
2815:RMS
2799:RMS
2768:20 - 500
2706:> 1500
2693:(meters)
2686:Frequency
2633:Carnarvon
2611:litz wire
2538:harmonics
2499:Fessenden
2333:in series
1736:inductors
1716:bandwidth
1704:resonance
1664:Marconi,
1645:frequency
1641:bandwidth
1291:receivers
1210:microwave
1196:and wire
1155:semaphore
1117:receiver.
1074:resonator
1048:spark gap
1036:frequency
931:antenna,
914:(at rear)
894:inductors
828:induction
798:telegraph
772:sine wave
735:sine wave
696:frequency
669:called a
660:earphones
652:frequency
588:π
491:frequency
479:amplitude
466:amplitude
323:spark gap
314:bandwidth
277:resonator
270:frequency
258:capacitor
235:kilovolts
181:spark gap
179:across a
166:electrons
158:frequency
127:bandwidth
7964:Category
7851:Internet
7841:CYCLADES
7758:Ethernet
7708:Concepts
7632:terminal
7583:wireless
7406:Bob Kahn
7249:Pioneers
7074:Internet
6965:Cable TV
6829:(1915).
6753:(9): 190
6723:20 March
6696:21 March
6558:Archived
6401:22 March
6016:14 April
5679:. London
5058:51671246
5004:April 8,
4790:, p. 6-7
4662:archived
3587:27 March
3331:16 March
3273:14 March
3151:See also
3043:feedback
3020:receiver
3012:megawatt
2973:hydrogen
2943:with an
2901:umbrella
2857:telegram
2784:trembler
2709:< 200
2669:Republic
2576:in phase
2550:Q factor
2419:quenched
2411:Max Wien
2295:(center)
2218:Cornwall
2206:receiver
2183:Cornwall
2153:(S1, S2)
1973:system.
1930:detector
1755:Q factor
1744:inductor
1687:(bottom)
1614:umbrella
1602:Q factor
1467:(bottom)
1463:(center)
1271:—
1184:made of
847:electric
741:set, an
640:detector
266:inductor
189:resonant
36:Frastanz
7984:Commons
7974:Outline
7927:Oceania
7846:FidoNet
7831:ARPANET
7644:circuit
7213:digital
6942:History
6480:4075587
6450:Bibcode
6259:26 June
5762:4075587
5732:Bibcode
5498:, p. 30
5479:9 April
5369:20 June
5256:Antenna
4837:8 March
4692:8 March
4655:20 June
4607:, p. 46
3269:: 92–97
3177:Coherer
3134:coherer
2905:flattop
2829:Titanic
2807:Titanic
2801:Titanic
2754:5 - 20
2740:5 - 20
2726:1 - 10
2703:Amateur
2238:ionized
2203:coherer
2076:(below)
2038:(right)
1963:(below)
1825:(right)
1708:syntony
1637:damping
1487:(right)
1443:(right)
1425:skywave
1151:horizon
779:History
768:(below)
423:ionizes
334:antenna
231:voltage
117:Titanic
7922:Europe
7892:Africa
7876:Usenet
7836:BITNET
7773:Mobile
7649:packet
7158:MOSFET
7153:device
6950:Beacon
6622:
6527:
6478:
6442:Nature
6308:22 May
6227:22 May
5894:
5840:
5813:
5760:
5724:Nature
5656:
5648:
5630:
5560:
5431:
5318:
5291:
5200:
5170:
5130:
5103:
5056:
5048:
4907:–180.
4741:22 May
4646:
4580:
4523:
4496:
4460:
4428:
4344:
4317:
4200:
4166:
4139:
4107:
4077:
4045:
4015:
3863:
3814:
3784:
3527:22 May
3467:
3433:
3406:
3376:
3244:
3217:
3094:funken
3084:Legacy
3058:triode
3006:range.
2567:dynamo
2415:series
2214:Poldhu
2179:Poldhu
2034:(left)
2006:(left)
1880:" or "
1821:(rear)
1734:) and
1668:, and
1598:damped
1565:, and
1483:(left)
1447:(left)
1257:charge
1192:, and
1190:sulfur
1182:lenses
1178:prisms
1170:optics
963:, and
929:(A,A')
667:switch
489:. The
327:switch
217:radio.
185:switch
7905:South
7900:North
7861:JANET
7798:Telex
7788:Radio
7627:Nodes
7622:Links
7543:media
7121:Radio
7106:Pager
7034:Drums
7000:video
6995:image
6985:audio
6743:(PDF)
6682:(PDF)
6592:(PDF)
6506:–263.
6476:S2CID
6356:(PDF)
6149:4 May
6108:(PDF)
6058:(PDF)
5758:S2CID
5654:S2CID
5054:S2CID
4775:–167.
4232:–185.
3943:–53.
3647:(PDF)
3612:–279.
3577:(PDF)
2971:in a
2925:ozone
2848:Nauen
2832:'
2717:Ships
2683:Uses
2637:Wales
2389:beats
2291:(top)
1951:(his
1803:jars.
1691:(top)
1394:Earth
1382:(E-F)
1378:(C-F)
1208:, or
1194:pitch
679:relay
656:audio
414:coil.
401:CQ DE
83:audio
64:radio
7917:Asia
7803:UUCP
7763:ISDN
6841:2015
6819:2015
6785:2019
6759:2015
6725:2018
6698:2018
6620:ISBN
6572:link
6525:ISBN
6403:2018
6368:2024
6339:2024
6310:2018
6261:2018
6229:2018
6178:2018
6151:2018
6124:2018
6074:2018
6018:2019
5957:2018
5892:ISBN
5838:ISBN
5811:ISBN
5685:2018
5646:ISSN
5558:ISBN
5522:2017
5481:2018
5429:ISBN
5371:2018
5316:ISBN
5289:ISBN
5268:2018
5198:ISBN
5168:ISBN
5128:ISBN
5101:ISBN
5046:ISSN
5006:2017
4959:2015
4839:2018
4811:–39.
4743:2018
4694:2018
4657:2018
4644:ISBN
4578:ISBN
4521:ISBN
4494:ISBN
4458:ISBN
4426:ISBN
4342:ISBN
4315:ISBN
4269:2018
4198:ISBN
4164:ISBN
4137:ISBN
4105:ISBN
4075:ISBN
4043:ISBN
4013:ISBN
3861:ISBN
3812:ISBN
3782:ISBN
3659:2022
3589:2018
3529:2018
3465:ISBN
3431:ISBN
3404:ISBN
3374:ISBN
3333:2018
3303:2015
3275:2018
3242:ISBN
3215:ISBN
3145:EMPs
3103:and
3052:and
2990:and
2982:The
2955:The
2903:and
2797:The
2731:Navy
2667:RMS
2232:and
2210:kite
2168:(C2)
1918:(C1)
1876:", "
1553:and
1421:ions
1289:and
1244:and
1232:and
1180:and
1141:and
849:and
787:and
399:of "
115:RMS
7808:WAN
7778:NGN
7768:LAN
7049:Fax
6990:DCT
6616:509
6504:259
6466:hdl
6458:doi
6446:107
6391:102
6199:357
5946:doi
5748:hdl
5740:doi
5728:107
5638:doi
5262:(1)
5038:doi
4905:173
4773:165
4636:doi
4258:doi
4230:172
3911:173
3651:QST
3610:275
2822:SS
2811:CQD
2662:SOS
2657:CQD
2581:VLF
2417:or
2402:'s
2331:(S)
2327:(M)
2323:(F)
2220:to
2160:(D)
1374:(B)
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