What does an antenna counterpoise do?
With a monopole antenna, the counterpoise functions as a ground plane, reflecting the radio waves radiated downward by the antenna. To perform adequately, the counterpoise should extend at least half a wavelength from the antenna tower in all directions.
What is a counterpoise grounding system?
Counterpoise grounding consists of conductors buried below the surface of the earth that are connected to a power-system ground point. In the case of a transmission tower, the connection point could be the tower footing or the grounded side of a lightning arrestor.
How long should my counterpoise be?
20-30 feet
Length of counterpoise should be a minimum of 20-30 feet but longer is better. If possible run the counterpoise above ground away from or perpendicular to the antenna wire and do not ground the counterpoise at the unun. You can also use the unun with no counterpoise or ground if your feedline is at least 25+ feet long.
Should counterpoise be grounded?
A radial or counterpoise of copper wire is thousands of times better at conducting RF and vastly reduces losses, making for a more effective antenna. Answer: Don’t earth/ground the balun.
How long should antenna radials be?
Increasing the number and length of radials will increase the antenna system’s SWR but this isn’t necessarily a problem provided your rig can cope. Elevated radials should be electrically 0.25l long. Elevated radials should be at least 0.05l above ground and, for safety reasons, not less than 2m high.
Why does adding radials to a 1/4 vertical antenna seem to increase the SWR?
Elevated radials are usually 1/4 wavelength because it’s a convenient resonant length, but even longer radials would be desirable if they didn’t make the overall antenna system reactive. But low SWR by itself tells us next to nothing about how well the antenna is performing.
How many radials do I need for a vertical antenna?
If you need a number to start, twenty 32-foot radials will give you a workable system with most vertical antennas. You might consider 65-foot radials if you use the low HF bands. As we increase to 32 radials, improvement continues.
How long should vertical antenna radials be?
What does counterpoise mean?
noun. Definition of counterpoise (Entry 2 of 2) 1 : counterbalance. 2 : an equivalent power or force acting in opposition. 3 : a state of balance.
Does an end fed antenna need a counterpoise?
5 Answers. 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”).
How many radials do I need for vertical antenna?
When do you use a counterpoise in an antenna system?
Counterpoises are typically used in antenna systems for radio transmitters where a good earth ground connection cannot be constructed.
How is a counterpoise connected to the ground?
It consists of a network of radial copper wires suspended above the ground, connected to the transmitter feedline ground. It is suspended about 8 feet above ground, so technicians can get access to the helix house at the foot of the tower. Antenna used in Lodge-Muirhead wireless system around 1900, the first counterpoise.
What do you mean by counterpoise in radio?
Counterpoise Definition. After all, the word “radial” hardly fits a group of parallel wires with no real connection to the antenna’s feed terminal. Counterpoise, in popular Ham radio conversation, has always described a conductor or group of conductors serving as an RF ground.
Can a ground radial be used as a counterpoise?
Ground radials are also not a practical solution for portable operations. A simple and portable alternative to this problem is a RESONANT COUNTERPOISE. As implied above, you need a low impedance ground connection for the outer shield of the coax right at the feedpoint of the antenna.