[Antennas] Diminishing Returns

Thu Jun 4 15:28:53 EDT 2009

David, just asking this question may start a religious war. However, I
believe the most efficient use of radial wire occurs when the tips of the
radials are about 0.025 wavelengths apart. For example, on 80 meters a
wavelength is about 260 feet. 0.025 X 260 = 6.5, so the tips of your
radials should be about 6.5 feet apart. If you use quarter wavelength
radials on 80 meters they will be about 65 feet, and thus the diameter of
the circle they cover will be 130 feet. The circumference of this circle
will be pi X 130 or approximately 408 feet. 408 divided by 6.5 is 62, so
about 60 radials is optimal if they are a quarter wavelength long. 
This is not to say that adding radials beyond this will not show
improvement. It is to say that if you want to improve on the 60 quarter
wave radial system, you are better served to begin making the radials
longer. Notice that if you follow the above logic and go for one-half
wavelength radials you end up with about 120 radials.
So your first statement is correct. You can't have too many, and more and
longer is always better. However, for a fixed amount of wire there does
appear to be an optimum tradeoff between length and density.
Regards, Merv W2OE 