What is counterpoise wire?
counterpoise, in electronics, portion of an antenna system that is composed of wires or other types of conductor arranged in a circular pattern at the base of the antenna at a certain distance above ground. Insulated from the ground, it forms the lower system of antenna conductors.
How does a counterpoise system work?
The counterpoise functions as one plate of a large capacitor, with the conductive layers in the earth as the other plate. Since the radio frequency alternating currents from the transmitter can pass through a capacitor, the counterpoise functions as a low-resistance ground connection.
How long should be a counterpoise for an end fed antenna?
A standard recommendation (see QST, March 1936, p. 32, “An Unorthodox Antenna”) is an 84′ long end fed and a 17′ long counterpoise (6.5′ for 20m). While these lengths have been shown to work well on many bands, which is helpful if you’re in a hurry to get on the air, read up on the topic and experiment.
What is the difference between a counterpoise and a radial?
Radials hug the ground to help provide a low loss return path for the RF that is soaking into the ground. A counterpoise is used to create an artificial ground when an antenna is elevated.
Do I need a counterpoise for end fed antenna?
No, it is not needed, but it can improve the antenna system. An EFHW is simply a half-wave length of wire and a matching device, and that’s it. Counterpoises are commonly added to shunt common mode reflections when operating outside of the wire’s resonant frequency to avoid RFI issues (“RF in the shack”).
Can a counterpoise be used as a ground wire?
The counterpoise can be a ground system like radials instead of a single counterpoise. It just cannot connect back to the station entrance ground, or the balun’s ground. If it is a single wire or a few wires, they should be insulated from earth and kept a little distance above earth.
Why are random wire antennas so difficult to use?
The difficult problems associated with random wire or longwire antennas are caused by ground currents and radiation from the single wire feeder. End-fed antennas, or antennas with the single wire feeder brought into the shack, come with a little misconception.
Can the counterpoise connect to the station entrance?
The counterpoise can be a ground system like radials instead of a single counterpoise. It just cannot connect back to the station entrance ground, or the balun’s ground.
What is the difference between a longwire and random wire antenna?
Technically a true “longwire” needs to be at least one wavelength long, but Hams commonly call any end-fed wire a longwire or random wire antenna. Long wire or random wire antennas are very simple antennas.