Editing Duplexer (section)

==History==
The first duplexers were invented for use on the [[electric telegraph]] and were known as ''duplex'' rather than ''duplexer''. They were an early form of the [[hybrid coil]]. The telegraph companies were keen to have such a device since the ability to have simultaneous traffic in both directions had the potential to save the cost of thousands of miles of telegraph wire. The first of these devices was designed in 1853 by [[Julius Wilhelm Gintl]] of the Austrian State Telegraph. Gintl's design was not very successful. Further attempts were made by Carl Frischen of Hanover with an artificial line to balance the real line as well as by [[Siemens & Halske]], who bought and modified Frischen's design. The first truly successful duplex was designed by [[Joseph Barker Stearns]] of Boston in 1872. This was further developed into the [[quadruplex telegraph]] by [[Thomas Edison]]. The device is estimated to have saved [[Western Union]] $500,000 per year in construction of new telegraph lines.<ref>Tom Standage, ''The Victorian Internet'', ch. 11, Walker & Company, 2007 {{ISBN|978-0-802-71879-2}}.</ref><ref>George Bartlett Prescott, ''Electricity and the Electric Telegraph'', pp. 792-793, New York: D. Appleton, 1877 {{oclc|999414808}}</ref>

The first duplexers for radar, sometimes referred to as Transmit/Receive Switches, were invented by [[Robert Morris Page]] and [[Leo C. Young]] of the [[United States Naval Research Laboratory]] in July 1936.<ref>Page, Robert Morris; ''The Origin of Radar'', Doubleday & Company, 1962, pp. 118-125</ref>