A <a href="https://en.wikipedia.org/wiki/counterpoise_(radio)" class="extiw" title="en:counterpoise (radio)">counterpoise</a>, a network of wires suspended above the ground under a transmitting radio <a href="https://en.wikipedia.org/wiki/antenna" class="extiw" title="en:antenna">antenna</a>, which functions as a <a href="https://en.wikipedia.org/wiki/ground_(electricity)" class="extiw" title="en:ground (electricity)">ground</a> connection for the transmitter.  The counterpoise consists of "star" of radial copper wires extending from the base of the antenna mast, connected at the center to the "ground" side of the radio <a href="https://en.wikipedia.org/wiki/transmitter" class="extiw" title="en:transmitter">transmitter</a>.  It is used in <a href="https://en.wikipedia.org/wiki/medium_wave" class="extiw" title="en:medium wave">medium wave</a> and <a href="https://en.wikipedia.org/wiki/longwave" class="extiw" title="en:longwave">longwave</a> radio transmitters when a low resistance ground connection cannot be constructed because of high soil resistance.  The counterpoise functions as a large <a href="https://en.wikipedia.org/wiki/capacitor" class="extiw" title="en:capacitor">capacitor</a> plate, with the conductive ground layers as the other plate.   In this example the ends of the radial wires are attached to a circular  nonconductive cord supported by insulators from a ring of poles.  The counterpoise is suspended high enough so that maintenance personnel can walk under it to reach the <a href="https://en.wikipedia.org/wiki/helix_house" class="extiw" title="en:helix house">helix house</a> feed enclosure located at the base of the antenna under the counterpoise.   The radial counterpoise wires should be about a quarter wavelength long if possible, and should not be electrically connected at the periphery, to prevent <a href="https://en.wikipedia.org/wiki/eddy_current" class="extiw" title="en:eddy current">eddy currents</a> from flowing in the loops which waste energy.  <br><br>
Alterations to image: Added two labels, "INSULATING SUPPORT" and "RADIAL WIRE" to the image to improve explanation
Edmund A. Laport
1952
Retrieved from  <a rel="nofollow" class="external text" href="http://snulbug.mtview.ca.us/books/RadioAntennaEngineering/">Edmund A. Laport, <i>Radio Antenna Engineering</i>, McGraw-Hill Publishing Co., New York, 1952, p. 53, fig. 1.14</a> on David Platt's webpage for this book