Topband: Elevated Radial Efficiency - an inordinately long post

[W0UN -- John Brosnahan]

At 22:53 28-11-07, William Culpepper wrote:
>I am ONE of the people who claim that four elevated radials can have
>approximately the same efficiency as 120 buried quarter wavelength radials.
>I have installed such systems at three Standard Broadcast stations in the
>United States, and made field strength measurements that, when analyzed in
>accordance with FCC procedure, showed that the unattenuated field strength
>at one kilometer was essentially the same as the FCC criteria for broadcast
>antennas with 120 buried  90 degree radials (Figure 8 of Part 73 of the FCC
>Rules).


(an inordinately long post -- and well worth it!)

William--

MANY THANKS FOR YOUR POST

I have been making this same claim for years, with a few caveats, 
such as the elevated radials must not be too close to the ground and 
should not be connected to an existing ground-mounted system.  And 
this limitation has been confirmed with the modeling that K3LC has 
done and published.

Elevated radials worked very well for me as far back as pre-1990 when 
I phased two 1/4 verticals on 160 with each vertical having four 
elevated radials.  75 JAs in the first contest from my CO QTH (with 
K0RF operating) made me feel pretty good about the system even if not 
actually proving anything.

I then followed this approach for my 160M 4-square with good results, 
even though I never got to use it much in the subsequent years due to 
other commitments.

Then K5IU's work was published that indicated even better results by 
making the individual radials non-resonant (resonance is where the 
slope of the reactance curve is maximum and where balanced 
(cancelling) currents are the most sensitive to variations in the 
soil, etc) and the total radial system should then be resonated with 
a single reactance.

I guess I was partly instrumental in getting W5UN to try this 
approach and Dave did extensive comparison testing between both an 
elevated radial antenna and a standard vertical over an extensive 
ground plane and became convinced that the elevated radial system, 
properly constructed, would equal a classic system.  His results with 
his 4-squares with elevated radials on both 160 and 80 would seem to 
confirm his decision.

Again, thanks for your detailed post.

73  John  W0UN