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Guglielmo Marconi: Application of Radio Waves to Communication, 1918

The Next Threshold

The next technical challenge was to increase the distance for transmission across seas and oceans. In December 1897, signals traveled up to 29 kilometers from a station on the Isle of Wight out to ferry boats in the English Channel, a locale know for treacherous weather conditions. On March 27, 1899, the bad weather was shown inconsequential as the first international transmission was made from South Foreland, near Dover, to the village of Wimereaux, near Boulogne. Now the navies of France, Britain, and the United States became very interested in the new technology and its strategic importance. Successful trials of ship-to-ship communication during maneuvers followed, and during the Boer War, which broke out in October of that year, ship-based wireless was put to valuable use.

At the turn of the century, the Marconi Company began to have some commercial success and the goal of passing the next threshold—transatlantic communication—was declared. This commitment was a daring undertaking for the young company but Marconi immediately pressed ahead. Land for the eastern station was found on a headland at Poldhu in the far southwest of England and land for the western station on a cliff-top near South Wellfleet on Cape Cod, close to the easternmost point in the United States. This arrangement provided a clear path for wireless transmission across the ocean. Work began on the powerful transmitters and enormous masts required for the project. A 25 kw power plant was built at Poldhu together with a system of 20 200-foot masts arranged in a 200-foot diameter circle. The same installation was built in Cape Cod. Before the systems could be tested, they fell victim to the fierce weather in their exposed locations: first the almost completed Poldhu aerial toppled and the masts at Cape Cod collapsed a month later. As usual, with Marconi's determination, rebuilding of a new, stronger aerial at Poldhu began immediately.

Another problem, that of signal interference, had to be overcome before transmissions across the ocean could be feasible. The high power necessary for longer range caused the signal to be diffused and interfere with other exchanges taking place between ships and shore. Marconi's patent number 7777 enabling selective wavelength tuning removed this problem.

Concerns grew about the signal power required for Poldhu-to-Cape Cod transmission, a distance of 4,000 km, and the decision was made to reduce this distance by moving the western terminal north to Newfoundland, Canada, an unimpeded 2,880 km from Poldhu. A station was built on Signal Hill, St. John's. On December 12, 1901, in the midst of a gale, with kites and aerials in danger of damage, Marconi detected and his assistant George Kemp confirmed the faint clicks of Poldhu's first transatlantic signal. This was an extremely memorable moment.

Marconi's success was celebrated in Canada and the United States. With financial incentives offered by the Canadian government, Marconi built his next, more powerful station in Glace Bay, Cape Breton. Transatlantic wireless service was established in December 1902.