Source of information :- wikipedia.org
Wednesday, July 20, 2016
Tribute to Guglielmo Marconi on his 79th death anniversary
Guglielmo Marconi, (25 April 1874 – 20 July 1937) was an Italian inventor and electrical engineer known for his pioneering work on long-distance radio transmission and for his development of Marconi's law and a radio telegraph system. He is often credited as the inventor of radio, and he shared the 1909 Nobel Prize in Physics with Karl Ferdinand Braun "in recognition of their contributions to the development of wireless telegraphy".Marconi was an entrepreneur, businessman, and founder of The Wireless Telegraph & Signal Company in the United Kingdom in 1897 (which became the Marconi Company). He succeeded in making a commercial success of radio by innovating and building on the work of previous experimenters and physicists. In 1929, the King of Italy ennobled Marconi as a Marchese (marquis).
Marconi was born into the Italian nobility as Guglielmo Giovanni Maria Marconi in Bologna on 25 April 1874, the second son of Giuseppe Marconi (an Italian aristocratic landowner from Porretta Terme) and his Irish/Scots wife Annie Jameson (daughter of Andrew Jameson of Daphne Castle in County Wexford, Ireland and granddaughter of John Jameson, founder of whiskey distillers Jameson & Sons). Between the ages of two and six, Marconi and his elder brother Alfonso were brought up by his mother in the English town of Bedford. After returning to Italy, at age 18 University of Bologna physicist Augusto Righi, neighbour of Marconi who had done research on Heinrich Hertz's work, permitted Marconi to attend lectures at the university and use the lab and library as well. Marconi received further education in Florence at the Istituto Cavallero and, later, in Livorno. Marconi did not do well in school, according to Robert McHenry, though historian Giuliano Corradi characterizes him in his biography as a true genius. Marconi was to Maria Christina in 1927.
During his early years, Marconi had an interest in science and electricity and in the early 1890s he began working on the idea of "wireless telegraphy"—i.e., the transmission of telegraph messages without connecting wires as used by the electric telegraph. This was not a new idea; numerous investigators and inventors had been exploring wireless telegraph technologies and even building systems using electric conduction, electromagnetic induction and optical (light) signalling for over 50 years, but none had proven technically and commercially successful. A relatively new development came from Heinrich Hertz, who demonstrated beginning in 1888 that one could produce and detect electromagnetic radiation—now generally known as radio waves, at the time more commonly called "Hertzian waves" or "aetheric waves".
There was a great deal of interest in radio waves in the physics community but the explorations were more along the lines of discerning the nature of the phenomenon. Physicists generally looked on radio as an invisible form of light, a short range phenomenon that could only be detected on line of sight making it unsuitable for communication. Hertz's death in 1894 brought published reviews of his earlier discoveries including a demonstration on the transmission and detection of radio waves by the British physicist Oliver Lodge and an article about Hertz's work by Marconi's teacher, Augusto Righi. Righi's article renewed interest in developing a wireless telegraphy system based on radio waves on the part of Marconi, a line of inquiry that he noted other inventors did not seem to be pursuing.
Marconi, just twenty years old, began to conduct experiments, building much of his own equipment in the attic of his home at the Villa Griffone in Pontecchio, Italy with the help of his butler Mignani. In the summer of 1894, he built a storm alarm made up of a battery, acoherer (an early detector that changed resistance when exposed to radio waves), and an electric bell, which went off if there was lightning. Soon after he was able to make a bell ring on the other side of the room by pushing a telegraphic button on a bench.
One night in December 1894, Guglielmo woke his mother and invited her into his secret workshop and showed her the experiment that he had created. The next day, he also showed his work to his father, who gave his son all of the money he had in his wallet when he was certain that there were no wires, so that Guglielmo could buy more materials.Marconi read through the literature and picked up on the ideas of physicists who were experimenting with radio waves, but did a great deal to develop devices, such as portable transmitters and receiver systems, that could work over long distances, turning what was essentially a laboratory experiment into a useful communication system. Marconi came up with a functional system with many components:
A relatively simple oscillator or spark-producing radio transmitter;
A wire or metal sheet capacity area suspended at a height above the ground;
A coherer receiver, which was a modification of Edouard Branly's original device with refinements to increase sensitivity and reliability;A telegraph key to operate the transmitter to send short and long pulses, corresponding to the dots-and-dashes of Morse code; and A telegraph register activated by the coherer which recorded the received Morse code dots and dashes onto a roll of paper tape.In the summer of 1895, Marconi moved his experimentation outdoors and continued to experiment on his father's estate in Bologna. He tried different arrangements and shapes of antenna but even with improvements he was only able to transmit signals up to one-half mile, a distance Oliver Lodge had predicted in 1894 as the maximum transmission distance for radio waves.
A breakthrough came that summer when Marconi found that much greater range could be achieved after he raised the height of his antenna and, borrowing from a technique used in wired telegraphy, grounding his transmitter and receiver. With these improvements the system was capable of transmitting signals up to 2 miles (3.2 km) and over hills. The monopole antenna reduced the frequency of the waves compared to the dipole antennas used by Hertz, and radiated vertically polarized radio waves which could travel longer distances. By this point, he concluded that a device could become capable of spanning greater distances, with additional funding and research, and would prove valuable both commercially and militarily. Marconi's experimental apparatus proved to be the first engineering-complete, commercially successful radio transmission system.
PB Parivar offers tribute to this great scientist on his 79th death anniversary.
Source of information :- wikipedia.org