The student executed Groups 2-KCK-12-1 Andreyev D. A.

When in 1887 the experiments the German physicist G.R. Gerts ( ) proved justice of a hypothesis of J. K. Maxwell ( ) about existence of the electromagnetic waves extending with velocity of light (called now radio waves), many inventors in the different countries dealt with an issue of use of these waves for wireless signaling. The considerable contribution was made in it by the French physicist E. Branli ( ), and also the English scientist O. J. Lodge ( ).

The first-ever broadcast was carried out in Russia by the well-known inventor and the scientist A.S. Popov ( ). In 1888 the scientist learned about opening of Hertz and immediately started their reproduction. In 1889 in one of the lectures, Popov for the first time pointed to possibility of use of electromagnetic waves for signaling on distance without wires.

Having examined Branli and Lodge's works, Popov continued to improve details of the transmitter and the receiver entering such important new elements, as the wire attached to the scheme, i.e. a prototype of the reception antenna (1894). At this time his friend and the assistant P. N. Rybkin started working with A.S. Popov ( ). On April 23 (on May 7 on new style) 1895 at meeting of the Russian physical and chemical society Ampere-second. Priests were shown by the device, "been the ancestor of all reception devices spark to "wireless telegraphy".

Having found out that the device reacts to lightning discharges, Popov created the "grozootmetchik" which has been almost used for reception of signals of approach of thunder-storms in meteorological observatory of capital Forest institute, at the Nizhny Novgorod fair and other cases. In the scientist improved the sending device. 12 on March (24), reception of the first-ever radiogramm in the Physical office of the Petersburg university on the Vasilyevsky island was organized. The station of departure was at distance of 250 meters, in Chemical institute. The telegraph transferring alphabetically Morse one letter for another was attached to an intake. The text of this dispatch said: "Heinrich Gerts".

Much the American scientist of the Yugoslavian origin N. Tesla ( ) dealt with a problem of wireless signaling. In he created the special high-voltage high-frequency resonant transformer which has played an exclusive role in further development of radio engineering. In Tesla I transferred radio signals at distance of 32 km. on the vessels moving across Hudson. Since 1901 with radio transmitters sea vessels began to be equipped. In 1905 American Forrest established a radio communication between the train in a way with stations on range of 50 km. In 1907 the reliable radio communication between Europe and America was established. In 1910 the steamship "Tennessee" received the message on a weather forecast from California at distance of 7,5 thousand km, and in 1911 the radio communication on 10 thousand km was reached.

Huge value for further development of telecommunication had emergence at a boundary of XIX and XX centuries of electron tubes. In 1883 Edison found out that the glass flask of a vacuum bulb of an incandescence darkens because of dispersion of a material of a thread. Subsequently it was established that "Edison's effect" emission of electrons by the heated thread of a bulb (the phenomenon of thermionic issue) is the reason of it. In 1904 the English scientist J. E. Fleming ( ) invented the vacuum diode (two electrode lamp) and applied it as the detector (the converter of frequencies of electromagnetic oscillations) in radiotelegraphic receivers. In 1906 the American designer Li de Forrest ( ) created a three- electrode vacuum lamp - the triode (Forrest's audion) which could be used not only as the detector, but also the amplifier of weak electric fluctuations.

4 years later engineers Liben, Reyks and Strauss in Germany designed the triode with a grid in the form of the punched leaf of the aluminum, placed in the cylinder center. However the first devices had weak coefficient of strengthening. Additional researches were necessary to turn the triode in the real amplifier. The regenerative scheme (1912) American radio technicians E.KH. Armstronga ( ) was this new device. It was the sensitive receiver and the first nonmechanical generator of pure continuous sinusoidal signals. Armstrong's regenerative scheme was quickly accepted by the industry. In 1915 between New York and San Francisco transcontinental telecommunication with application of regenerative repeaters was established.

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