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]
antennex
was invoked but never defined (see the help page).