What is Counterpoise in an Antenna System?

What is Counterpoise in an Antenna System?

A simple definition of counterpoise is a conductor or system of conductors used as a substitute for earth or ground in an antenna system. A counterpoise could be used by a radio amateur residing on a higher level of a modern residential system with no access to the actual ground. A network of horizontal wires parallel to the ground suspended above the ground under the antenna and connected to the transmitter’s ground connection is an elaborate example.

Counterpoise may also be used when the ground has high electrical resistance as in dry, sandy or rocky soil. It would function as one plate of a large capacitor with the conductive layers of the earth acting as the other plate. Radiofrequency currents from the transmitter can pass through this capacitor so that the counterpoise functions as a low resistance ground connection. But there should not be any closed loops in the wires of a counterpoise system. In such a case, strong fields of the antenna will induce circular currents in it and dissipate transmitter power.