> 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
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