[TowerTalk] Raised Radial Spacing

[Jim Brown]

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