History of radio 

With the telegraph and the telephone, the man could communicate over long distances, even across the seas by submarine cables, but only between the points that came with these cables. But there were still cut off the boats, vehicles, sparsely populated, and so on. Overcoming these difficulties began to be possible with a series of discoveries during the development of electricity, had appeared several theories to explain many kinds of electrical phenomena, it was believed at first that the electrical action occurred at a distance on the various bodies and could experience it. But the discovery of electricity led to any doubt that mysterious action. Faraday did not believe that action adistancia and in 1835, writing about a perfected form of voltaic battery, noted that the electrical current is propagated as if there were discrete particles of electricity.Faraday's ideas were forgotten and his compatriot Maxwell picked them thirty years later, to translate them into mathematical language, drawing from them the most momentous consequences. James Clerk Maxwell in 1867 presented his electromagnetic theory (Electricity and Magnetism) at the Royal Society of London. This theory, obtained by pure mathematical calculation, predicted the possibility of creating electromagnetic waves and their propagation in space. These waves propagate through space at speeds of 300 thousand kilometers per segundo.Las first attempts to confirm this theory were made by Professor Fitzgerald, of Dublin, but gave no practical results until the German physicist Hertz, who was unaware of the Fitzgerald's investigation, undertook the same task. The German Heinrich Hertz in 1887, experimentally confirmed Maxwell's theory, and studying radiating electromagnetic waves with its oscillator and a resonator, made the first wireless transmission, what thereafter would be named in his honor waves hertzianas.Este experiment served to confirm the ideas of Maxwell and hinted the possibility of producing electric waves at a distance and capture them by suitable apparatus. It was therefore the first attempt to radio via electromagnetic waves, and the first practical result of which was to germinate experimentos.El full range of discovery Hertz, although allowed to prove the existence of electromagnetic waves and their properties Fates those of light waves, confirming Maxwell's theory brilliantly, had no immediate practical results, because the resonator, which revealed the presence of waves, could only run a short distance from the apparatus that producía.En Calzecchi Onesti 1884 found electrical conductivity that make the iron filings in the presence of electromagnetic waves, or wave French hertzianasEl Branly, in 1890, built his primitive choesor (coherer), which allowed the presence of radio waves, ie to detect and that would be used by all researchers then wanted wireless communication (wireless). The Branly coherer consists of a glass tube in which iron filings are something tight, metal poles between two communicating with an electric battery. The resistance of the filings is too high to pass the battery power, but in the presence of Hertzian waves that conductivity increases and the current through the device can be seen ringing a bell Branly eléctrico.Con apparatus could be captured radio waves at distances much greater than the Hertz resonator, but anyway, still could not be obtained in practical applications. The Russian Popov believed found in the Branly tube a sensitive device to reveal the progress of the storm, as the shock of the storm clouds cause the formation of waves, can be revealed by the Russian cohesor.El Popov (1859-1905 ) found the best system to radiate (send) and catch the waves: antenna, consisting of wire. After perfecting this device, Popov added to the system receiving a wire extended vertically so that the rise in the atmosphere, might better capture the electrical oscillations. This wire was attached by one end to one pole of the coherer, while the other end communicated with earth so that any potential difference that exists between the poles, caused by the passage of an electromagnetic wave from the clouds stormy, rang the bell of the device, which more or less frequent tapping idea of ​​giving up the tempestad.De Thus was born the first antenna, named because, to hold the wire developed by Popov, had used a support look like the masts or antennas buques.El March 24, 1896 made the first wireless communication signals. These early transmissions were made up of single pulses, obtained by powerful electric current discharge capacitors or stored in Leyden jars. A coil of conductive wire, located a few meters from the discharge, producing a discharge between its ends lower oscillator abiertos.El Hertz, Branly detector antenna Popov and were, therefore, the three essential elements in establishing a system of radio, but also requires a structure which could operate safely for having been able to get comerciales.Nadie applications, until in 1895, Marconi conducted experiments that provided the final title of inventor of radiocomunicación.Este phenomenon began to show Electrical resonance was studied by Marconi, which in Bologna (Italy) in 1896 and only 20 years old getting his first press prácticos.Empleando a vertical wire or "antenna" instead of rings cut and using a "detector" or device allowing weak signals to discover, soon managed to establish communication over distances of 2400 m.Paulatinamente was increasing the scope of its transmissions, until in 1896 obtubo requested and the first patent for a system of telegraphy inalámbrica.Pero can actually say that Era of the Wireless Telegraphy began a raw day, December 12, 1901 at 24:30 and after raising the receiving antenna with balloons and kites to 120 mts. height, in abandoned barracks in St. John's (Canada) where Marconi assisted by Messrs. Paget and Kemp, managed to capture a series of three points, the Morse code letter S, a signal had to travel the 3,600 miles separating Marconi (Poldhu) Cornwall, Great Britain (England). This signal was the culmination of many years of experimentación.Después Event Marconi Transatlantic in 1901, the United States there has been a rapid development in self-testing devices and TSF (wireless telegraphy). By the year 1900 he began using crystal detector for the detection GALENA replacing the Branly coherer, galena was much more sensitive, but even inestable.En 1897, OJ English Lodge invented the tuning system, which allows using the same receiver to receive different emisiones.En 1897, using a transmitter consisting of a large induction coil, and raising the transmitter and receiver antennas using kites (kites), increased the scope of 14.5 km team also showed that transmission could be on the sea, establishing communication between two ships of the Italian Navy, at distances of 19 km above the figure gives an idea of ​​their first contact receptor.El radio in France took place in 1898 between the Eiffel Tower and the Pantheon (4 km) in 1899 again Paris. researcher and inventor Guglielmo Marconi managed to send a radio message across the English Channel linking Dover with Wimereux (46 km). This is the year 1899, occurred the first demonstration of the value of communications by radio to give more security to travel in the sea when the ship's "RF Mathews" was saved after the crash of a light boat, thanks to call for help by radiotelegrafía.Con voltages only a few hundred volts could get a signal streaming or sustained, which rapidly reversed spark transmitters. What is more, the continuous signal was easily modulated by carbon microphones, the kind that is still commonly used in phones today, and allowed the transmission of this voz.Fue Dr. Lee DeForest which launched the first emissions speech and music radio, using the bulb of the invention to generate electromagnetic waves rather than sparks.His broadcasts from his home in California were rather experimental until finally, in 1920, the Westinghouse Electric and Manufacturing Co., established in the first season radiofusora Pittsburgh office: the famous "KDKA." Radiotelegraphy This led to the telephony, there would be a vast field of possibilities to the great human adventure in communications.