Counterpoise (ground system)

In electronics and radio communications, 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 or when an antenna is mounted above ground level, for example, on a building.

Source: Wikipedia — Counterpoise (ground system) (CC BY-SA 4.0)