The shorter the vertical section of a loaded vertical,
the lower the radiation resistance. I believe there is
a curve of this in the later ARRL Antenna Books.
Remember, a full 1/4 vertical over a perfect ground
has a radiation resistance around ~ 32 ohms.
I modeled this some time ago and assume the
data is somewhere in the radio room.
On Mon, 19 Aug 2002 "Kelly Taylor" <firstname.lastname@example.org> writes:
> Hi all,
> I've noticed that of 10 most recent messages from TT, 10 were about
> double posts to the reflector or the spelling of lightning. Zero
> actually had anything to do with antennas or towers. (BTW: since at
> that's somewhat related to TT, the facts rest in W0UN's favour.
> Lightning is
> that bright flash of light during a t-storm; lightening is to move
> from a
> darkened (or heavy) state into a less dark, or less heavy, state.
> One is a
> noun, one is a verb. So sayeth Mr. Oxford.)
> So in the interests of relieving off-topicitis, here's one message,
> least, that IS about towers or antennas: I am trying to build a
> 80-meter inverted L. Feedpoint is six feet above ground, with the
> rising 26 feet to an insulator and then 40 feet south in an
> horizontal position. Counterpoises are two horiz. wires at six feet
> one of which (under the top portion) is 66 feet, the other is as
> long as
> available space permits.
> I haven't yet started pruning, but thanks to a borrowed MFJ 209, I
> see that
> even at the dip (about 2.8 MHz), the SWR is 3:1. It's been a while
> (at least
> two kids) since I played antenna guru, but am I missing something
> I plan to as soon as I get a chance (the aforementioned two kids,
> just force feed it with the autotuner and see how it plays, but I'd
> interested in any feedback you might have.
> Self Supporting Towers, Wireless Weather Stations, see web site:
> Call 888-333-9041 to place your order, mention you saw this ad and
> take an additional 5 percent off
> any weather station price.
> Towertalk mailing list
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