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Selasa, 11 Februari 2014

Biography of Guglielmo Marconi

Biography of Guglielmo Marconi

        Marconi, Guglielmo (1874-1937). He was the originator of wireless telegraph signals and created means of overcoming many of the hurdles to the commercialization of wireless. He was the first to transmit signals across the ocean without use of cables. Marconi was born in the Italian countryside in somewhat modest circumstances. He had little formal education, though his mother tutored him, and he loved to read from his fathers library about experiments with electricity. Marconi audited courses at the University of Bologna, since he could not gain admittance to the university for credit, and studied under Augusto Righi, a scientist who had worked with electromagnetic waves.
Since Righi was also a neighbor, Marconi would often visit him with questions and ideas. Righi rarely encouraged Marconi’s ideas about a practical system of transmitting information using these electromagnetic waves. Still, Marconi showed a dogged persistence in trying out method after method in his experiments.
In 1895, at the age of 21 after following the experiments of Heinrich Hertz, Marconi devised a system that allowed him to ring a bell two rooms away in his attic workshop purely by striking a telegraph key that created electromagnetic waves. He began producing this effect at longer and longer distances, eventually moving outside and sending the signals several hundred yards.
Early on, distances were overcome simply by using more powerful electrical charges, a condition that would never allow practical wireless communication to travel very far. Marconi eventually found that if part of the transmitter were placed on the ground resistances were cut dramatically and the signal would travel much farther. Thus, Marconi invented the grounded antennae and began sending telegraph signals up to two miles, even through hills and obstacles.
After the Ministry of Post and Telegraph in his home country rejected his initial presentation of the invention, he took it to England. After applying for a patent to protect his idea, he began working to gain British support. Since his mother was Irish, he had several family connections in England and was able to arrange a presentation to William Preece of the British postal system in 1896. Preece became an avid supporter and provided postal system personnel to help Marconi continue to develop his system. By 1899, Marconi had established a wireless link across 32 miles of the English Channel.
The system of wireless as it then existed still allowed for only one person to transmit in an area at a time. Multiple transmissions would be incomprehensible or would cancel each other out. Marconi looked for a way to tune the signal to specific wavelengths. He succeeded in developing a system of tuned multiplex telegraphy in 1900, which allowed multiple messages to be sent on the same transmitter simultaneously with each message received accurately by a different receiver.
Another obstacle to be overcome by Marconi was a belief by many scientists that electromagnetic waves would not be able to follow the curve of the Earth and could, therefore, never transmit signals across the vastness of an ocean. In 1899, Marconi had transmitted signals from ship to shore over a 66 nautical mile span, far more than enough to ensure that the waves were somehow bending around or traveling through the ocean to reach the shoreline. Marconi was convinced that the wireless could span the ocean and he set out to prove it.
He had a powerful transmitting station built in Poldu on the English coast and set sail for St. Johns, Newfoundland. Pretending to be working on contacting passing ships on their transatlantic voyages, he launched a kite with a receiving wire 400 feet into the air. On December 12, 1901, he received the letter “S” several times and had an assistant verify the reception. He then announced to the world what he had done. He had received a message from over 2100 miles across the Atlantic.
Still, many doubted due to the bias of his only witness and the simplicity of the message. So Marconi next outfitted a ship with a sophisticated wireless equipment, a telegraph recorder that would mark the signals on paper tape, and a public listening room so that passengers and crew would be witness to receptions. He received signals over 2000 miles from England. He also found, however, that the signals traveled the distance best at night, a phenomenon he was at a loss to explain.
In 1907, Marconi finally perfected the system of transatlantic wireless and began commercial service between Glace Bay, Nova Scotia, Canada and Clifden, Ireland. His work on wireless brought him the Nobel Prize for physics in 1909.
The early 1910s were full of lawsuits defending his patent rights, which he won, and were financially profitable for Marconi’s British, American, and international companies. World War I intervened, however, and in 1916, the American Marconi Company was forced to merge with General Electric and others by the U.S. government. America wanted to avoid foreign control in wireless properties used by the military, and they pressured the companies to merge and form RCA under control of Americans. Thus, Marconi lost the influence he had established in wireless communication in America.
In Britain, however, Marconi and his companies were influential in the startup of public radio broadcasting and help establish the British Broadcasting Company, later the British Broadcasting Corporation or BBC.
Marconi continued to experiment on improving radio. He eventually was able to send messages in specific directions and around the globe. He also performed experiments with radar and with microwave, proving that microwaves could also travel beyond the horizon of the Earth. In 1924 he set up a system of wireless stations that linked the British colonies around the world with England. He also set up radio service for the Vatican in Rome in 1931 and created the first microwave link so that the Pope’s messages could be broadcast live to the world, though they were given miles from the short wave transmitter. Failing health restricted Marconi’s activity for several of his last 10 years of life. He died of heart failure in 1937.







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