On Mon, 27 Jun 2011 18:21:50 -0700, "Wayne"
wrote:

I have seen two commercial antennas advertised that are each 43 feet tall,
and have no traps/stubs, etc.
There appears to be a 4:1 balun at the feedpoint. Mentioned, is the
requirement to have a tuner at the driving end of the feedline, and max
VSWRs in the 4:1 range.

Playing around a bit with EZNEC, the feedpoint impedances over the
operating range have some large swings. Can anyone shed light on how
effective the antenna should be?
Wayne
W5GIE

Hi Wayne,

Actually, it depends more on the ground, or its proximity. If you can
get all the energy into the antenna (hence the tuner and BalUn), then
it leaves (the whole point of our hobby). If you have very few
radials and you are close to ground, when that energy leaves, a lot of
it is absorbed into the ground (not very productive).

Now, the height of this radiator can be something of bad thing for the
higher bands. 10M will become deaf because most of the energy is
oriented high into the sky, and deep into the ground. True, you
"could" force a decent match, but that is only half the story of
antennas. The same is probably true for 11M, 12M, down to a fairly
good match and operational application for 20M and below to, maybe,
60M.

EZNEC should bear out instructive numbers and graphics to all these
observations.

One curiosity about this - the 4:1 BalUns. This sounds like a Hail
Mary throw - a sop for the sucker. Do you count yourself among that
select population? Why? Because technically they would be UnUns.
Further, it is strange to think that a transformation ratio of 4:1 is
applicable anywhere, much less everywhere.

73's
Richard Clark, KB7QHC