[Elecraft] Small QRP antenna

[Jim Brown]

On Thu,12/29/2016 1:53 PM, Bill Frantz wrote:
> If this is really what is going on, then a bit longer than 1/8 wave 
> should be about right for radials on/under the ground.

I did an NEC study several years ago placing a half wave dipole at 
heights above ground from several feet down to an inch, and varied the 
length of the dipole so that it remained resonant at each height. From 
that I plotted VF. As close to the earth as I could model it, VF was 
about 0.7. At heights of 3 ft or more, VF on 160M was close to 1.

N6LF published a detailed study of radial lengths and recommended an 
optimum length for elevated radials slightly less than a quarter wave. 
His basis was that making them slightly shorter caused current 
distribution between them to be more equal, which reduces ground losses. 
Rudy's website is a wealth of great info about radials.

73, Jim K9YC