On 10/24/2025 4:03 PM, Dale Dean wrote:
Any other suggestions?
Hi Dale,
I did a deep dive on this about 15 years ago, and came up with this set
of slides for a talk that I've done at ham conventions and to several
clubs. None of it is my original work, all the collection of work by
others.
http://k9yc.com/160MPacificon.pdf
In general, for on-ground radials, more is better and resonance is less
important than more. Remember that the function of radials is NOT to
couple to the earth, but to provide a low-loss path for return current,
and also to SHIELD the antenna's field from the the earth. There is a
great treatment of this in the Handbook or Antenna Book, by K3LA (I hope
I got his call right), that it took a while for me to get my head around.
The definitive contemporary work on radial systems is probably by Rudy
Severns, N6LF, all of which I have devoured. In retirement, hee's taken
his website with all of his work offline, thinking no one would be
interested! K6STI is working on getting it back online, perhaps from
the "wayback machine, the internet archive. I can relate -- I'm 84, have
done a lot of work I hope will remain, and that the latest versions of
my work, which includes the latest stuff I've learned, will be
available. Likewise, guys like W3LPL and N6BT have been and still are
making important contributions to the state of our art.
Rudy's work was an important light-bulb for me, AND for all of ham
radio. Why are more radials better? The earth couples to radials as
series R. Loss in that R is I squared R, as the number of radials
increases, the current in each divides between them. That is a LINEAR
relationship, but power is I SQUARED. So loss drops in proportion to the
number of identical radials (equal current distribution).
A similar relationship happens with chokes in series, which linearly
increases both their power handling and their choking impedance.
73, Jim K9YC
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