[TowerTalk] Topband: Radials on ground v FCP

[Lux, Jim]

On 1/11/22 1:55 PM, Wes wrote:
> I've already posted a copy of what N7CL posted to this group years 
> ago.  His work, as well as the work of others, can also be found in 
> ON4UN's  "Low Band DXing" starting on page 9-14 of the 5th edition.  
> The answer is there.
>
> Additionally see: "A Closer Look at Vertical Antennas With Elevated 
> Ground Systems" by Rudy Severns N6LF.  He recommends 10-12 elevated 
> radials as a minimum.
>
> Wes  N7WS

My ON4UN is not readily to hand, so I couldn't check it.


Rudy has a wealth of modeled and measured data, but the only comparison 
I saw with height of radials was between 8 feet (about 0.03 lambda) and 
6" (0.002 lambda).

And the difference was <0.25 dB (Figure 13).

Jim's comment was that N6BT had recommended 20ft for 160m and that Jim 
saw a significant improvement  going from 6 ft to 20 ft. Which is 
inconsistent with Rudy's observations.

But what I was getting at was not just the phenomenology but the 
underlying physics.

The radials over ground thing is an interesting problem, because there's 
a lot going on.