Q Lou, KB6JLI, asks, “While reading an advertisement for a vertical antenna, I noticed the ad mentioned that no radials are needed, but it also says that you need to use an 80- foot counterpoise. Please clarify for me the difference between a radial and counterpoise. Aren’t they basically the same?”
A The difference between the terms “radial” and “counterpoise” is subtle, but significant. Radials usually consist of multiple bare wires either buried in, or laid upon, the ground and are not tuned to a specific frequency. Such wires don’t really show a resonance because they are coupled so heavily to the lossy Earth. Their purpose is solely to reduce ground losses (very good information on this topic can be found in the 19th edition of The ARRL Antenna Book, starting on page 6-24).
A counterpoise is a wire or group of wires mounted close to ground, but insulated from ground, to form a low-impedance, high-capacitance path to ground. The purpose of a counterpoise is to provide an RF ground for the antenna.
From QST March 2001
