Does a random wire need a counterpoise?
(A random-wire antenna needs a good ground regardless of how much power you’re running.) If your radio room is in the basement or on the first floor, you may be able to use a cold water pipe or utility ground. On higher floors you’ll need a counterpoise.
Do I need an unun for random wire antenna?
Random wire antenna, a.k.a. long wire antenna Both a 9:1 unun and a 1:1 RF choke is used for the random wire antenna.
How long does it take to counterpoise?
20-30 feet
Length of counterpoise should be approx. 20-30 feet but NOT resonant. If possible run the counterpoise away from or perpendicular to the antenna wire. You can also use the unun with no counterpoise or ground if your feedline is at least 25+ feet long.
How long should my wire antenna be?
You also want the antenna to be at least 1/4 wavelength long for each band you plan to use. For instance, to work 40m be sure the antenna is at least 10m or 33′ long.
What is a 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.
What is a long wire or random wire antenna?
Long wire or random wire antennas are very simple antennas. They can come close to half wave antennas in efficiency, although efficiency decreases as they are made very long or installed closer to earth. Like every antenna that exists, random or long wires have advantages and disadvantages. Advantages Disadvantages
Can a single wire counterpoise be connected back to the ground?
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. Ideally the single wire counterpoise should be directly under the longwire antenna, and a few feet above earth.
Do end-fed antennas need a counterpoise?
End-fed antennas, or antennas with the single wire feeder brought into the shack, come with a little misconception. One commonly repeated myth or “theory” is that half-wave antennas, being resonant, do not require a counterpoise, or that some magical length of antenna will prevent RF in the shack.
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.