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The History of Modern Coaxial Cables

Coaxial cable is at the center of the world of audio and video communication. It is used to bring cable television, high-speed Internet, telephone service, and radio service into homes and businesses across the world. Many people believe that coaxial cable is an invention of the 20th century. However, they are surprised to learn that coaxial cable is actually an invention that goes back to the time of the American Civil War.

The History of Coaxial Cable

Coaxial cable as it is currently known came about during the aftermath of World War II. Hams began using it because it was relatively inexpensive since there was a surplus of it in military depots. However, the geometry behind the coaxial structure, that is one conductor that is centrally located surrounded by another, stems from a mathematical analysis that was done by theorists in the 19th century as they explored electromagnetism.

Of course, that theory did not lead to a working prototype until sometime around 1850 as engineers were working on the idea of creating transatlantic cable communications. In fact, the very first cable used in telegraph communications was a form of coaxial cable because it had a centrally located conductor that was encased in a cylindrical material used for installation. These early cables took advantage of the seawater’s ability to conduct electricity to help them complete and return their circuit.

The Appearance of Modern Coaxial Cables

As the years progressed, researchers fine-tuned the coaxial cable. The first patent for a coaxial cable was filed in May 1929. The patent was received in December 1931 for what was then referred to as a concentric conducting system.

Interestingly, at its inception, modern coaxial cables were not used for radio transmissions. Instead, they were used to transmit television signals over long distances. In 1936, two of the major communication companies at the time used coaxial cable to conduct a 100 mile long underground voice transmission experiment. This was done by using two rounds of coaxial cable, one for each direction of the transmission with repeaters that were located every 10 miles. The voice transmission went from New York to Philadelphia and back. Additionally, in that same experiment, they transmitted telegraph signals and fax signals.

Since that time, advances in technology have made using, transmitting, and boosting signals via a coaxial cable easier. Devices like a 0 degree divider allow transmissions to be sent over longer areas than ever before.

http://www.arrl.org/files/file/Technology/pdf/QST_Aug_2001_p62-64.pdf

By Ryan

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