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 a counterpoise be grounded?

The counterpoise will act as a series resistance with a distributed leakage to ground. A counterpoise would be in excess of a grounding electrode system, not in lieu of, or would be installed for the purposes of a LPS as indicated by you. But for nothing more than the ease of bonding all down conductors together.

Does an inverted V antenna need a balun?

Dipoles have a feed point of about 75Ω in free space, and can be fed with 50Ω to 75Ω coax with or without a 1:1 balun. Inverted Vee’s present closer to 50Ω due to the effect of the ground being close to the tip of each leg. Feed your inverted vee with 50Ω coaxial cable, with or without a 1:1 balun.

What is the difference between a counterpoise and a radial?

Vertical antennas can have radials mounted on or below the surface of the actual ground. If the radial system is mounted above the ground, it is technically a counterpoise and takes the place of the actual ground.

How high should inverted antenna be?

The antenna is placed in the shape of an inverted V, with its two transmission lines or legs bent towards the ground making 120° or 90° angle between them. The center of the antenna should not be higher than λ/4.

Do I need a counterpoise?

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”).