Capable of sending Morse code signals through airwaves, Guglielmo Marconi’s wireless telegraph ushered in a revolutionary period in communications that would later include radio broadcasting, television, radio astronomy, and radar.
Communication during the late nineteenth century was firmly based on the electric telegraph, invented by Samuel F. B. Morse in 1838. In both the United States and Europe, telegraph lines strung along poles connected even the most remote settlements. Transatlantic communication had even been possible since 1866, when a cable had been successfully placed across the ocean. Telegraphs could only use the Morse code, a system of dots and dashes devised by Morse, instead of either the alphabet
Guglielmo Marconi (right) and the American chemist Irving Langmuir (1881-1957) in the General Electric Research Laboratory in 1922.
The beginnings of a new system that would eventually lead to both voice and music being broadcast throughout the world without the use of wires were not obvious at first. For decades, physicists had known that electromagnetic waves act at a distance without a physical medium. In 1873, James Clerk Maxwell
Six years later, a young Italian by the name of Guglielmo Marconi came across a report on Hertz’s experiments and decided that here was a method that could be used to communicate Morse code without wires. Using equipment invented by a number of other scientists, he attempted to lengthen the distance the electromagnetic waves could be transmitted. When the distance grew to more than a mile, he tried to attain a patent in his native Italy in 1895. With telegraphy firmly in place on land, the only function the patent officials saw for the device was to allow ships to communicate with each other and the shore. Marconi headed to England, thinking his chances for approval might be better in a country with the largest fleet in the world. While in Great Britain, he received a patent for the wireless telegraph in June, 1896.
Marconi was not satisfied with a device that could only transmit within a one-mile radius, so he continued to improve the wireless telegraph. Over the next few years, the distance increased to four, then seven, and then twelve miles. In 1899, Marconi succeeded in transmitting from England to France across the English Channel, a distance of thirty miles. Marconi focused on maritime events, such as yacht racing, and worked to provide ways for ships to signal distress at sea. He also sought to provide a wireless telegraph in those areas inaccessible to or awkward for telegraph poles, such as on the coast, where winds off the ocean regularly destroyed telegraph lines connected to lighthouses, or across wide rivers, where telegraph lines could not be strung with ease.
Also in 1899, Marconi moved to the United States and set up the Marconi Wireless Telegraph Company of America. He began marketing his device and became quite successful. Competitors quickly arose, however, and one of the early problems of radio communications was interference among competing stations. The different stations needed a way to transmit at different frequencies so that receivers could distinguish the desired signal. Marconi again experimented with devices developed by other inventors until he had a tuner that would radiate strongly with little interference. He received a patent for the mechanism in 1900.
The next step for Marconi was to attempt to broadcast radio waves across even greater distances than before. He was convinced that transatlantic signaling could be accomplished. Prevalent theories deemed this impossible. Radio waves travel at the speed of light in straight lines. After radio waves passed the horizon, they would merely radiate out into space, not follow the curvature of the earth to reach far distant places. Since Marconi was already obtaining distances twice as long as that required to reach the visible horizon, he saw no reason why the distance could not be increased even further.
In order to achieve radio signals across the Atlantic, Marconi built huge power stations with tall antennas, one at Poldhu in Cornwall
Theories abounded concerning radio’s newfound ability to transmit over such long distances. The one most accepted was that a region of the atmosphere must reflect the radio waves, allowing them to extend farther than expected. It was not until the 1920’s that researchers experimented with sending radio waves up into the atmosphere to discover various regions that reflected radio waves in various ways. This layer of the atmosphere is called the ionosphere. During the day, sunlight ionizes molecules within this region and hinders radio transmissions; at night, the effect is lessened.
Marconi might have impressed the world with the first transatlantic radio transmission, but in the meantime he had his hands full trying to keep his company competitive. The radio wave detector of the time was a coherer, a tube of glass full of metallic particles that would cohere when radio waves passed through them. At a tap, they would fall apart again. Marconi designed a magnetic detector in 1902 that could work continuously. His new detector was also faster and longer lasting than a coherer.
Marconi’s invention replaced the telegraph as the sole means of communicating news across long distances and became the most versatile means of communication of the twentieth century, with applications in entertainment, news broadcasts, military detection systems, and astronomy.
Radio as Marconi envisioned it used long waves at high energies to travel. He was certain that long waves were necessary for long distances, and large power stations were set up to propagate these waves. Radio amateurs, limited to small power supplies, were forced to use shortwave radio and achieved good results. Shortwave radio was able to maintain contact more regularly than long wave, and it traveled longer distances, too. In the 1920’s, Marconi reversed his position and began researching shortwave radio. His efforts provided a reliable means for long-distance communication.
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Coe, Lewis. “Without Wires.” In The Telegraph: A History of Morse’s Invention and Its Predecessors in the United States. Jefferson, N.C.: McFarland, 1993. Traces Marconi’s earliest breakthroughs and the transformation of nineteenth century communications systems from telegraph to early radio. -
Leinwoll, Stanley. From Spark to Satellite: A History of Radio Communication. New York: Charles Scribner’s Sons, 1979. Carefully reports the history, the people, the scientific theory, and the technology of radio from Marconi to radio astronomy. -
Pierce, John R., and A. Michael Noll. “Electric and Electronic Devices: The Physics of Communication Systems.” In The Science of Telecommunications. New York: Scientific American Library, 1990. A clear, detailed description of the device Marconi invented, with color photographs, electrical diagrams, and a brief biography. -
Rhoads, B. Eric. “Who Really Invented Radio?” Audio 79 (December, 1995): 26-31. A brief yet thorough summary of the technology and inventors of early radio. Clearly explains radio’s mechanisms and early patents, with many pertinent photographs. -
Strebeigh, Fred. “Messages by Wireless.” In Inventors and Discoverers: Changing Our World, edited by Elizabeth L. Newhouse. Washington, D.C.: National Geographic Society, 1988. Traces the history of wireless communication from the first laboratory transmissions to television, with numerous color photographs coupled with informative captions. -
Weightman, Gavin. Signor Marconi’s Magic Box: The Remarkable Invention of the Nineteenth Century and the Amateur Inventor Whose Genius Sparked a Revolution. Cambridge, Mass: Da Capo Press, 2003. Biography of Marconi tracing his invention and its effects upon twentieth century culture.
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James Clerk Maxwell; Samuel F. B. Morse; Aleksandr Stepanovich Popov.