And, with all of that said, Tom - your technical evaluation and "cautionary"
statements are spot on and I, for one, enjoy reading and assimilating as much
of it all as my feeble brain allows - your final statement " there will always
be mixed review of results, and why having it work at one place does not mean
it will work some other place even when EXACTLY duplicated" gives hope to those
of us who, in this instance (the K6STI horizontal loop), don't have the space
to assemble and install 83 Beverage antennas and 4-squares and....
Y'all get the picture ----------- it's the FUN associated with trying a new
antenna out, AS LONG as we realize that what works in eastern east be-Jesus
Timbultu may not do so well in s/w Utah or where ever we all live.
I see this "signature" from another ham who posts at the QRP reflector --- "I
LOVE this radio stuff" - and I am so IN to that attitude.
Thanks to all for keeping the discussions alive from a technical as well as
anecdotal perspective(s) 'cuz that IS the real world!
72, Jim Rodenkirch K9JWV
> From: w8ji@w8ji.com
> To: topband@contesting.com; charleswshaw@gmail.com
> Date: Wed, 3 Oct 2012 10:03:59 -0400
> Subject: Re: Topband: K6STI low noise receive loop
>
> > I built one right after the article appeared in QST. I live in
> > the country with no close neighbors and had practically no noise to begin
> > with. So I didn't notice a difference in reception, and I didn't keep it
> > long. At that time the only RX antenna I had was a 160M dipole a 50 feet.
>
>
> This antenna should be very subject to feed system errors, surroundings, and
> local noise sources. The reason this happens is this antenna "fights" the
> earth reflection and itself with the small remainder the useful signal.
>
> 1.) The horizontal sections do not respond well because earth is cancelling
> the primary response. There is very little horizontal component of electric
> field, because earth shorts the horizontal component. The dominant allowed
> horizontal response is straight up to the sky.
>
> 2.) The out of phase element coupling and close spacing cancels radiation at
> all angles, but has the least cancellation along the horizon. This forces a
> null in the highest response direction, straight up.
>
> 3.) What remains is an exceptionally low signal response between those two
> nulls, the null along earth caused by earth conductivity and the null
> straight up caused by out-of-phase elements.
>
> The result is that a model, where the earth is ideally perfectly homogeneous
> and the area is clear, shows an excellent local noise groundwave null. The
> antenna, however, is so insensitive that any small errors have a large
> effect on results. Many of these errors are beyond control of the builder,
> because they would involve soil characteristics and coupling to anything
> around the antenna.
>
>
> When an antenna has very low response, it does not want to respond to any
> signals, it becomes extremely sensitive to things that unbalance the system.
> Its function is also dependent on local dominant noise propagating from
> somewhat distant groundwave sources, because it nulls groundwave to get rid
> of noise.
>
> This is why there will always be a very mixed review of results, and why
> having it work at one place does not mean it will work some other place even
> when EXACTLY duplicated.
>
> 73 Tom
>
> _______________________________________________
> UR RST IS ... ... ..9 QSB QSB - hw? BK
_______________________________________________
Remember the PreStew coming on October 20th. http://www.kkn.net/stew for more
info.
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