To: <topband@contesting.com>
> Date: Tue, 03 Mar 1998 21:50:33 -0600
> From: Merv Schweigert <k9fd@htc.net>
> Interesting the replies to Johns comments about spacing
> beverages away from the transmit antenna.
> I have the same experience as his, any beverage that runs
> in any proximity to the transmit vertical is influenced by it.
I agree with you Merv. It certainly is influenced.
A spirited debate about antenna performance when one wire is stuck
randomly in the near field of other large wires (or antenna) is all
but meaningless. In those situations, the results are a matter of
pure blind luck and happenstance rather than being a repeatable
discovery.
The best idea is always to keep antennas a reasonable distance away,
if you can. Otherwise, it's a lottery game.
> By the way my "vertical" is a tower with raised radials, the radials
> going to the coax center conductor and the shield to the tower..
> The N4KG method.
> Maybe a setup with radials in or on the ground works better
> with beverages ?..
Not only with Beverages nearby, it also works better for
transmitting. Raised resonant radials radiate like crazy and couple
to EVERYTHING else in the near field (including lossy soil below the
antenna) no matter how much time is wasted pruning and tuning. The
fields from each radial only cancel completely hundreds of feet away,
and that is where they don't cause power loss.
You also likely give up a lot of useful RF to the loss in the tower
to earth connection, which modeling programs often "think" is a zero
ohm zero loss connection. In the real world, a tower stuck in the
mud is not a zero ohm lossless earth termination!
Raised radials are a great idea if they are installed a hundred feet
in the air, but place anything (including good ole dirt) within a
pretty large distance and the radials couple like crazy to
whatever the other conductor is. And that's true no matter how
much time is wasted "tuning and pruning" them for equal currents.
73, Tom W8JI
w8ji.tom@MCIONE.com
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