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