Counterpoise (ground system)

Ground screen, similar to a counterpoise, at base of mast antenna of AM radio station KTBS
Diagram of counterpoise under the antenna mast of an AM radio station. It consists of a network of radial copper wires suspended above the ground, connected to the transmitter feedline ground. It is suspended about 8 feet above ground, so technicians can get access to the helix house at the foot of the tower.
Antenna used in Lodge-Muirhead wireless system around 1900, the first counterpoise.

In electronics and radio communication, a counterpoise is a network of suspended horizontal wires or cables (or a metal screen), used as a substitute for an earth (ground) connection in a radio antenna system. It is used with radio transmitters or receivers when a normal earth ground cannot be used because of high soil resistance[1] or when an antenna is mounted above ground level, for example, on a building. It usually consists of a single wire or network of horizontal wires, parallel to the ground, suspended above the ground under the antenna, connected to the receiver or transmitter's "ground" wire.[2] The counterpoise functions as one plate of a large capacitor, with the conductive layers of the earth acting as the other plate.[2][3]

The counterpoise evolved with the Marconi (monopole) antenna during the 1890s, the first decade of radio in the wireless telegraphy era, but it was particularly advocated by British radio pioneer Oliver Lodge,[4][5] and patented by his associate Alexander Muirhead[6] in 1907.[7]

  1. ^ Cite error: The named reference antennex was invoked but never defined (see the help page).
  2. ^ a b Laporte, Edmund (1952). Radio Antenna Engineering. MicGraw-Hill. pp. 52–53.
  3. ^ United States Bureau of Naval Personnel (1973). Basic Electronics. Washington DC: Courier Corp. p. 523. ISBN 9780486210766.
  4. ^ Lodge, Oliver (1925). Talks about Wireless. Cambridge University Press. pp. 91–92. ISBN 110805269X.
  5. ^ Simmons, Harold H. (1908). Outlines of Electrical Engineering. New York: Cassell and Co. pp. 853–854.
  6. ^ Alexander Muirhead, British patent no. 11271 "Hertzian Wireless Telegraphy"
  7. ^ Eckersley, T. L. (May 1922). "An investigation of transmitting aerial resistances". Proc. of the Inst. Of Electrical Engineers. 60 (309). London: E. and F. N. Spon: 599. Retrieved October 3, 2013.

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