A NVIS antenna is a stupid idea. I agree with his Elmer, NVIS means "Not
Very Intelligent Selection." Do you notice that that is all we hear about
today-how everyone is using a NVIS antenna. Doesn't anyone want to work DX
anymore?
73s John NE0P
----- Original Message -----
From: "Tom Rauch" <w8ji@contesting.com>
To: <towertalk@contesting.com>
Sent: Friday, July 22, 2005 2:55 AM
Subject: Re: [TowerTalk] dumbing down
> > At 02:44 PM 7/21/2005, SavageBR@aol.com wrote:
> > >BTW we're not dumbing down TowerTalk.
>
> > >Indirectly Tower Talk and any other technical reflector
> is being dumbed
> > >down. Or, the need is being eliminated. As the
> technically competent,
> > >experienced, capable amateur dies off, so will the real
> hobby of
> > >amateur radio.
>
> > To relate it more to antennas.. I think that amateurs are,
> in general, much
> > more sophisticated when it comes to antennas these days.
> Compare the
> > antenna projects in ARRL handbooks over the years. Some
> are perennial
> > evergreens, but modern directive antennas are far better
> than what was
> > "state of the art" in 1960 or 1970.
>
> I almost hate to post this, but I seriously question the
> direction our technical resources are heading.
> I think peer review processes are slipping. Let me give an
> example.
>
> August QST, page 35, has a very well written four page
> antenna construction article. It unfortunately has a very
> simple basic point wrong. The authors based the construction
> on the incorrect assumption a small horizontal loop antenna
> radiates a vertically polarized omni-directional signal. Of
> course it doesn't have vertical polarization. It radiates an
> omni-directional horizontally polarized signal!
>
> The article claims a comparison was made between the loop
> and a J-pole. It said signals were "even". That can't be
> true in line-of-sight communications unless the J-pole had
> some very serious flaws or an esoteric effect like feedline
> radiation or metallic structures nearby was affecting
> antenna patterns.
>
> If you read the editor's note on page 35 it says: "While
> horizontal loops do better in noisy situations because that
> local noise tends to be mainly E-field oriented ....". What
> does that mean? What is "mainly E-field oriented"?
>
> Now here's the real sad part. The antenna isn't good for the
> original intent...efficient omni-directional vertically
> polarized communications.....no matter how we position the
> loop. Turn the loop on edge and it has a bi-directional
> vertically polarized signal while wasting half of the
> applied power as straight-up-and-down horizontally polarized
> radiation. Lay it down flat and it is omni-directional, but
> unfortunately it is also horizontally polarized.
>
> Articles like this embarrass and discourage everyone from
> the authors to the editor to the poor fellow trying to learn
> how to build something. They should be edited and corrected
> before publication, not after.
>
> Now if you roll over to Technical Correspondence on page 60,
> you find an opening letter about Packet, Pactor, and NVIS.
> The letter writer wastes no time in being critical of an
> older Elmer (he actually used those words) who thought the
> idea of an 18 inch high dipole antenna for 80 or 40 was a
> dumb idea.
>
> The writer uses some fantasy technorubbish about groundwave
> and NVIS being "out of phase" and the 18 inch high antenna
> curing a "phase distortion" problem.
>
> Well, I'm in full agreement with the older Elmer. The only
> thing that happens when a horizontal dipole antenna is
> installed significantly lower than 1/4 wl is the efficiency
> drops, often like a rock!
>
> Thirty years ago people knew if we wanted a dynamite NVIS
> signal we installed a dipole at 1/8 to 1/4 wl high and laid
> a screen or grid of wires below the antenna to reduce earth
> losses. Now we have people proclaiming in the best interests
> of "Homeland Security" communications we need to use what
> really amounts to a 10 dB or more attenuator on a 5 to 10
> watt transmitter... rather than building a good system.
>
> This is probably why, when I listen to the GA ARES net, a
> significant number of stations can't hear each other. Yet
> with a dipole 35 feet high over a large ground screen I can
> hear and work all the dog-gnat signals coming from grossly
> inefficient antennas that are (no surprise) quiet. This is
> where we are headed.
>
> How do we educate people and build reliable communications
> networks when many technical concepts making it into what
> once was our only peer reviewed reliable source of
> information are getting so ridiculous?
>
> The CB'er down the road has metal pie pans with holes in the
> center strung on his coax to "divert lightning" and an old
> water cooler jug filled with pennies and saltwater for a
> station ground. I fully expect to see that idea published
> someday in a radio communication system handbook. After
> all, steel wool baluns made it in, and we now have 18 inch
> high dipoles that cancel phase distortion and horizontal
> loops that radiate a vertically polarized omni-directional
> signal. Pie pans seem the next logical progression.
>
> 73 Tom
>
> _______________________________________________
>
> See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless
Weather Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any
questions and ask for Sherman, W2FLA.
>
> _______________________________________________
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>
_______________________________________________
See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless Weather
Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any questions
and ask for Sherman, W2FLA.
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