John, N9JG wrote:
My antenna is a Butternut HF6V vertical. This antenna is ground mounted and
has 32 radials, which have been laid on top of the grass. The average length
of the radials is about 30 feet. I operate primarily on 40 meters, and I
seem to receive good signal reports.

Today, I ran into another operator on 40 meters, who told me that I would
get a large signal improvement if I increased the number of radials from the
current 32 to 100 or 120. In fact he said he had seen information on the
SteppIR website (http://www.steppir.com/) that supported his assertion.
Remembering how hard I had worked to install my existing 32 radials, I
responded that the effect of quadrupling my radial count would probably give
only a small increase in gain of less than one dB. Indeed Cebik's website
(http://www.cebik.com/gp/gr.html) seems to support this view with a graphic
titled "Radial Length vs. Number of Radials". If I am interpreting this
graphic correctly, the gain increase from 32 radials to 128 radials is about
0.5 dB.

Any comments would be gratefully received.

John, N9JG


Hi John,

I once had a 30m Vertical ground mounted with 120 radials and it worked
great.. but it work quite well with the 40 or so I had at first also..
the other dynamic that is at work that you hardly ever hear about is
that as you increase the number of radials say from your 32 to approach
100 or so you also need to increase their length so it approaches
1/2wave for each radial.

as a rule of thumb you should keep adding radials until you see no
further change in antenna input impedance. At that point it is not
worth the effort or expense to add more.

73 Dave kc1di