Coaxial cable
A Coaxial cable is a special electrical cable. It is used to transmit signals. The cable is specially insulated. This makes it quite stiff. Today, coaxial cables are used for things like Cable TV. Coaxial cables can also be used for computer networks, but this is more rarely the case now, as twisted pair cables can be used there more easily.
Such cables are usually made of a conducting wire. Then there is some insulation, then there is another layer of conducting material. Finally there is the (insulating) mantle. Such cables are used as a high-frequency transmission line to carry a high-frequency or broadband signal. Because the electromagnetic field carrying the signal exists (ideally) only in the space between the inner and outer conductors, it cannot interfere with or suffer interference from external electromagnetic fields.
There are different types of coaxial cables, which satisfy different standards.
[change] Timeline
- 1880 — Coaxial cable patented in England by Oliver Heaviside, patent no. 1,407.
- 1884 — Coaxial cable patented in Germany by Ernst Werner von Siemens, but with no known application.[source?]
- 1894 — Oliver Lodge demonstrates waveguide transmission at the Royal Institution. Nikola Tesla receives U.S. Patent 0,514,167, Electrical Conductor, on February 6.
- 1929 — First modern coaxial cable patented by Lloyd Espenschied and Herman Affel of AT&T's Bell Telephone Laboratories, U.S. Patent 1,835,031.
- 1936 — First transmission of TV pictures on coaxial cable, from the 1936 Summer Olympics in Berlin to Leipzig.
- 1936 — World's first underwater coaxial cable installed between Apollo Bay, near Melbourne, Australia, and Stanley, Tasmania. The 300-km cable can carry one broadcast channel and seven telephone channels.
- 1936 — AT&T installs experimental coaxial telephone and television cable between New York and Philadelphia, with automatic booster stations every ten miles. Completed in December, it can transmit 240 telephone calls simultaneously.[1]
- 1936 — Coaxial cable laid by the Post Office (now BT) between London and Birmingham, providing 40 telephone channels. [Source: archives at http://www.bt.com]
- 1941 — First commercial use in USA by AT&T, between Minneapolis, Minnesota and Stevens Point, Wisconsin. L1 system with capacity of one TV channel or 480 telephone circuits.
- 1956 — First transatlantic coaxial cable laid, TAT-1.
[change] References
- ↑ "Coaxial Debut," Time, Dec. 14, 1936.
