[TowerTalk] Number of Radials and what lengths vertical 80m up.

[Jim Brown]

On 8/21/2018 3:18 PM, W1JCW John wrote:
> Putting a steppIR Big IR 80m - 6m.
>
> What length of radials should I put on and what lengths?

Will the antenna be ground-mounted or elevated?  The advice about four 
resonant radials per band is specific to elevated radials. For on-ground 
radials, the best rules of thumb are: 1) more radials are better 2) 
longer is better 3) radials on the ground will resonate roughly 30% 
higher in frequency than if they were elevated. #3 means, for example, 
that quarter-wave radials for 80M should be about 66 ft if elevated or 
about 46 ft if on the ground. 4) Length of on ground radials is not 
critical, more short radials close to the antenna matter more than a few 
longer ones.

There are slides for a talk I've done at several hamfests and clubs 
about radial systems for vertical antennas for 160M. The same concepts 
apply to higher bands, simply scaled to frequency. 
http://k9yc.com/160MPacificon.pdf

I agree that N6LF's work is definitive, and much of what's in those 
slides is derived from his work. KV4FZ's advice about using wire mesh to 
form a ground screen is also excellent. You'll find details about that 
in my slide show.

73, Jim K9YC