1895 __ Long-distance wireless communication
‣ Comment : Guglielmo Marconi successfully transmits in Pontecchio near Bologna, Italy a "dot-dot-dot" radio signal (the Morse code for letter "S") between two reciprocally invisible points separated by a hill and a distance of a few hundred meters. The radio communication is born. (Matthew T. Ciolek) — In the villa in Pontecchio near Bologna, the twenty-years-old boy transformed the granary in his laboratory, working night and day among rolls of copper wire, brass spheres, Ruhmkorff coils, Morse keys and electric bells, realizing the first elementary radio sets. The first weak signals could reach few hundred meters: from the window of the granary where was placed the transmitter to the hill at the end of the garden where was the receiver, the three points of the letter S travelled the space, reaching the destination, and the farmer waved his handkerchief to show the successful reception. But Marconi wanted to get over the obstacles of the ground and connect two reciprocally invisible points. He took the receiver to the other side of the hill, where Mignani with his gun waited for the ring to sound three times. From the granary Marconi pushed three times the key of the transmitter and heard the answer of a distant gunshot: electromagnetic waves had overtaken the obstacle, radio communications where now possible! It was the month of april 1895. For this experiments Marconi used the oscillators of Hertz and Righi, but the waves where too weak to go too far. He overcame the difficulties connecting to the oscillator an antenna and a ground, thus obtaining more power. (Brunero, Angelo and Andrea Valori. 2001, “The invention of the radio”) — By the time he was nineteen, he had resolved to be the first man to give the world a system of communication based on electromagnetic waves. By trial and error, relying on his own intuition and audacity, Marconi conducted a series of experiments indicating that long-distance wireless communication was possible. One problem remained. Scientific theory of the time asserted that radio waves followed straight lines that would leave the earth's atmosphere and continue into space. Marconi had a hunch, unsupported by any scientific proof, that the waves would be drawn by gravity and follow the curvature of the earth. If he was right, a powerful signal could cross an ocean. Marconi set out to prove that global transmission was possible. He built a transmitter in Poldhu, Cornwall, in England, and a crude receiver in the Cabot Tower in St. John's, Newfoundland. His experiments proved that rigid antennae could not withstand the North Atlantic winds, so he decided that in Newfoundland he would use a kite to raise the aerial high enough to capture the signal from England. (Compiled from various sources) — « I placed a single ear-phone to my ear and started listening… The receiver on the table before me was very crude... [but] I was at last on the point of putting the correctness of all my beliefs to the test... ...Suddenly, there sounded the sharp click of the ‘tapper’... and I listened intently. Unmistakably, the three sharp clicks corresponding to three dots [Morse Code for the letter S] sounded in my ear. ».
‣ Source : Ciolek, T. Matthew (2000), “Global Networking: a Timeline”, electronic publication, Research School of Pacific and Asian Studies, Australian National University, Canberra, 2000.
‣ Urls : http://www.free103point9.org/studycenter/historicaltransmissionworks/ (last visited ) http://www.cisi.unito.it/marconi/radeng.html (last visited )
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