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  1. › wiki › Nicola_TeslaNikola Tesla - Wikipedia

    5 days ago · Later called the Tesla coil, it would be used to produce high-voltage, low-current, high frequency alternating-current electricity. He would use this resonant transformer circuit in his later wireless power work. Citizenship. On 30 July 1891, aged 35, Tesla became a naturalized citizen of the United States.

    • Austrian (1856–1891), American (1891–1943)
    • 7 January 1943 (aged 86), New York City, U.S.
    • Wireless Communication Theories and Methods Previous to Radio
    • Development of Electromagnetism
    • Pre-Hertz Radio Wave Detection
    • Development of Radio Waves
    • Adaptations of Radio Waves
    • Radio Based Wireless Telegraphy
    • Wireless Telephony
    • Radio Invention Timeline
    • See Also
    • Further Reading

    Before the discovery of electromagnetic waves and the development of radio communication there were many wireless telegraph systems proposed and tested. In April 1872 William Henry Ward received U.S. Patent 126,356 for a wireless telegraphy system where he theorized that convection currents in the atmosphere could carry signals like a telegraph wire. A few months after Ward received his patent, Mahlon Loomis of West Virginia received U.S. Patent 129,971 for a similar "wireless telegraph" in July 1872. The patented system claimed to utilize atmospheric electricityto eliminate the overhead wire used by the existing telegraph systems. It did not contain diagrams or specific methods and it did not refer to or incorporate any known scientific theory. In the United States, Thomas Edison, in the mid-1880s, patented an electromagnetic induction system he called "grasshopper telegraphy", which allowed telegraphic signals to jump the short distance between a running train and telegraph wires...

    Various scientists proposed that electricity and magnetism were linked. Around 1800 Alessandro Volta developed the first means of producing an electric current. In 1802 Gian Domenico Romagnosi may have suggested a relationship between electricity and magnetism but his reports went unnoticed. In 1820 Hans Christian Ørsted performed a simple and today widely known experiment on electric current and magnetism. He demonstrated that a wire carrying a current could deflect a magnetized compass needle. Ørsted's work influenced André-Marie Ampèreto produce a theory of electromagnetism. Several scientists speculated that light might be connected with electricity or magnetism. In 1831, Michael Faraday began a series of experiments in which he discovered electromagnetic induction. The relation was mathematically modelled by Faraday's law, which subsequently became one of the four Maxwell equations. Faraday proposed that electromagnetic forces extended into the empty space around the conductor,...

    The earliest known record of an effect attributable to radio waves is the effect observed by George Adamswho in the early 1780s noticed sparks between charged and uncharged conductors when a Leyden jar was discharged nearby. During 1789-91, Luigi Galvani noticed that a spark generated nearby caused a convulsion in a frog's leg being touched by a scalpel.In different experiments, he noticed contractions in frogs' legs caused by lightning and a luminous discharge from a charged Leyden jar that disappeared over time and was renewed whenever a spark occurred nearby. Joseph Henryobserved magnetised needles from lightning in the early 1840s. In 1852 Samuel Alfred Varleynoticed a remarkable fall in the resistance of masses of metallic filings under the action of atmospheric electrical discharges. Towards the end of 1875, while experimenting with the telegraph, Thomas Edison noted a phenomenon that he termed "etheric force", announcing it to the press on November 28. He abandoned this resea...

    The Branly detector

    In 1890, Édouard Branly demonstrated what he later called the "radio-conductor," which Lodge in 1893 named the coherer, the first sensitive device for detecting radio waves. Shortly after the experiments of Hertz, Branly discovered that loose metal filings, which in a normal state have a high electrical resistance, lose this resistance in the presence of electric oscillations and become practically conductors of electricity. This Branly showed by placing metal filings in a glass box or tube,...

    Lodge's demonstrations

    British physicist and writer Sir Oliver Lodge came close to being the first to prove the existence of Maxwell's electromagnetic waves. In a series of spring 1888 experiments conducted with a Leyden jar connected to a length of wire with spaced spark gaps he noticed he was getting different size sparks and a glow pattern along the wire that seemed to be a function of wavelength.Before he could present his own findings he learned of Hertz' series of proofs on the same subject. On 1 June 1894, a...

    J. C. Bose

    In November 1894, the Indian physicist, Jagadish Chandra Bose, demonstrated publicly the use of radio waves in Calcutta, but he was not interested in patenting his work. Bose ignited gunpowder and rang a bell at a distance using electromagnetic waves,confirming that communication signals can be sent without using wires. He sent and received radio waves over distance but did not commercially exploit this achievement. Bose demonstrated the ability of the signal to travel from the lecture room,...

    Popov's lightning detector

    In 1894-95 the Russian physicist Alexander Stepanovich Popov conducted experiments developing a radio receiver, an improved version of coherer-based design by Oliver Lodge. His design with coherer auto-tapping mechanism was designed as a lightning detector to help the forest service track lightning strikes that could start fires. His receiver proved to be able to sense lightning strikes at distances of up to 30 km. Popov built a version of the receiver that was capable of automatically record...

    Tesla's boat

    In 1898 Nikola Tesla developed a radio/coherer based remote-controlled boat, with a form of secure communication between transmitter and receiver, which he demonstrated in 1898. Tesla called his invention a "teleautomaton" and he hoped to sell it as a guided naval torpedo.


    Guglielmo Marconi studied at the Leghorn Technical School, and acquainted himself with the published writings of Professor Augusto Righi of the University of Bologna. In 1894, Sir William Preece delivered a paper to the Royal Institution in London on electric signalling without wires. In 1894 at the Royal Institution lectures, Lodge delivered "The Work of Hertz and Some of His Successors". Marconi is said to have read, while on vacation in 1894, about the experiments that Hertz did in the 188...


    Ferdinand Braun's major contributions were the introduction of a closed tuned circuit in the generating part of the transmitter, and its separation from the radiating part (the antenna) by means of inductive coupling, and later on the usage of crystals for receiving purposes. Braun experimented at first at the University of Strasbourg. Braun had written extensively on wireless subjects and was well known through his many contributions to the Electrician and other scientific journals. In 1899,...

    Stone Stone

    John Stone Stone labored as an early telephone engineer and was influential in developing wireless communication technology, and holds dozens of key patentsin the field of "space telegraphy". Patents of Stone for radio, together with their equivalents in other countries, form a very voluminous contribution to the patent literature of the subject. More than seventy United States patents have been granted to this patentee alone. In many cases these specifications are learned contributions to th...


    In late 1886, Reginald A. Fessenden began working directly for Thomas Edison at the inventor's new laboratory in West Orange, New Jersey. Fessenden quickly made major advances, especially in receiver design, as he worked to develop audio reception of signals. The United States Weather Bureau began, early in 1900, a systematic course of experimentation in wireless telegraphy, employing him as a specialist. Fessenden evolved the heterodyneprinciple here where two signals combined to produce a t...


    In November 1904, the English physicist John Ambrose Fleming invented the two-electrode vacuum-tube rectifier, which he called the Fleming oscillation valve. for which he obtained GB patent 24850 and U.S. Patent 803,684. This "Fleming Valve" was sensitive and reliable, and so it replaced the crystal diode used in receivers used for long-distance wireless communication. It had an advantage, that it could not be permanently injured or set out of adjustment by any exceptionally strong stray sign...

    De Forest

    Lee De Forest had an interest in wireless telegraphy and he invented the Audion in 1906. He was president and secretary of the De Forest Radio Telephone and Telegraph Company (1913). The De Forest System was adopted by the United States Government, and had been demonstrated to other Governments including those of Great Britain, Denmark, Germany, Russia, and British Indies, all of which purchased De Forest apparatus previous to the Great War. De Forest is one of the fathers of the "electronic...

    Below is a brief selection of important events and individuals related to the development of radio, from 1860 to 1910.


    1. Edwin Howard Armstrong, Greenleaf Whittier Pickard, Ernst Alexanderson, Archie Frederick Collins, Alexander Stepanovich Popov, Roberto Landell de Moura


    1. Radio communication system, Timeline of radio, Oldest radio station, Birth of public radio broadcasting, Crystal radio


    1. Radio People, Radio Pioneers, Discovery and invention controversies

    Anderson, L.I., "Priority in the Invention of Radio: Tesla vs. Marconi", Antique Wireless Association Monograph No. 4, March, 1980.
    Anderson, L.I., "John Stone Stone on Nikola Tesla's Priority in Radio and Continuous-Wave Radiofrequency Apparatus", The AWA Review, Vol. 1, 1986, pp. 18–41.
    Brand, W.E., "Rereading the Supreme Court: Tesla's Invention of Radio", Antenna, Volume 11 No. 2, May 1998, Society for the History of Technology
    Lauer, H., & Brown, H. L. (1919). Radio engineering principles. New York: McGraw-Hill book company; [etc., etc.]
  2. 6 days ago · Zero-point energy ( ZPE) is the lowest possible energy that a quantum mechanical system may have. Unlike in classical mechanics, quantum systems constantly fluctuate in their lowest energy state as described by the Heisenberg uncertainty principle. As well as atoms and molecules, the empty space of the vacuum has these properties.

  3. › wiki › Cbs_LogoCBS - Wikipedia

    Sep 13, 2021 · CBS is an American commercial broadcast television and radio network.It serves as the flagship property of the CBS Entertainment Group division of ViacomCBS.The network is headquartered at the CBS Building in New York City, with major production facilities and operations at the CBS Broadcast Center in New York City, and CBS Television City and the CBS Studio Center in Los Angeles.

    • United States
    • January 15, 1929; 92 years ago
  4. Examples of high power-to-weight ratios can often be found in turbines. This is because of their ability to operate at very high speeds. For example, the Space Shuttle 's main engines used turbopumps (machines consisting of a pump driven by a turbine engine) to feed the propellants (liquid oxygen and liquid hydrogen ) into the engine's ...

  5. Sep 17, 2021 · High frequency AC sounds very similar to standard AC, but gives an impression of increased purity to the sound. The main disadvantage of HF AC is some difficulty in measuring the output voltage and getting it right - while electronic transformers are easy to modify, the calculation might be elusive to most DIYers.

  6. › frequenze-pmr-75FREQUENZE PMR PDF

    Sep 16, 2021 · Ultra high frequencyWikipedia. Radio spectrum Television technology Wireless. Atmospheric moisture reduces, or attenuatesthe strength of UHF signals over long distances, and the attenuation increases with frequency. Breakfast Club Power C band K u band L band S band. Wikimedia Commons has media related to Frequenae radios.

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