On 8/29/2020 9:24 PM, Robert Harmon wrote:
I wonder if he has done any testing of shortened radials ? Need to find
out........... Inquiring minds want know, hihi.
Last time I studied Rudy's work on radials was his 2-part QEX piece,
reprinted on his website. The "slightly less than a quarter-wave"
applied specifically to elevated radials, for which he also said more
than four (8-12) also helped equalize currents. It's the inequality that
increases loss.
For on-ground radials, length is far less critical, more is better, and
the shortening effect of ground yields a VF on the order of 0.7, making
a quarter-wave about 90-100 ft. I got this result by modeling a dipole
and moving it closer to ground. I did NOT have the licensed version of
NEC, so take that result with a grain of salt. :)
My two verticals with elevated radials have only four each -- with
falling branches during winter storms, it's hard to keep that many, plus
two Beverages and two VE3DO loops in the air. :) When trying to work EU,
I can really tell if one of the radials is on the ground.
Don't know what I'm going to find when returning from evac after the
fire. House is still good, we'll see about the antenna farm.
73, Jim K9YC
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