[Lowfer] FW: 600MRG> Helically wound vertical on a city lot>NO WAY!!!

[WE0H]

Here goes a good argument if anyone wants to take it on. This is all about
some other guy wanting to build a helical wound vertical for 166.5kc. I told
him that it wouldn't work and to use a typical 50' Lowfer vertical with some
radials and a good coil/variometer. He didn't like my suggestion nor does
this guy below. His address is john@mcaulay.net.

73's,
Mike>WE0H
http://www.geocities.com/we0h/index.html

-----Original Message-----
From: owner-shrmg@piobaire.mines.uidaho.edu
[mailto:owner-shrmg@piobaire.mines.uidaho.edu]On Behalf Of JMcAulay
Sent: Friday, March 22, 2002 4:56 PM
To: shmrg@piobaire.mines.uidaho.edu
Subject: Re: 600MRG> Helically wound vertical on a city lot>NO WAY!!!


CAUTION -- PHILOSOPHICAL STUFF:

"Common sense is just another term for the prejudices we grew up with."
    -- Stephen Hawking

I watched part of the Men's figure skating World Championships last night.
I was especially impressed by a skater who attempted a quad Lutz, never
before done in competition.  He fell.  But he got up and skated a
remarkable remainder of his program.  He finished out of the medals, but I
thought it was marvelous that he was willing to try something extraordinary.

That struck me as contrary to the decision by some people that LF antennas
are best done only in a certain way.  I have extremely high respect for the
work of the serious Lowfers.  I said months ago that those of us in this
group may never find through our experimentation nearly as much as the
Lowfers have already discovered.  But the fact that many (most? all?) of
them have decided that one generic antenna design is best for their
purposes is no reason not to try anything else.  Neither should the cry
"that won't work" be a reason not to try.  Sure, we know that certain
antennas will perform in certain ways.  But not everything is known about
antennas, regardless of what anyone may think.  And that includes the
computer program writers and users.  In my opinion, which you may feel free
to value highly, not at all, or anywhere in between, the only way to really
find out how well something works is to build it and try it.  If you do not
want to do that, it's fine with me.  I may choose to do something which
looks crazy to you, and that's fine with me, too.  As Douglas Adams said,
to be a true scientist, one must be willing to be thought a fool.  If you
know I plan to do something, and you personally have done it before, I
would appreciate any input regarding your experience.  And I will thank you
for it.  But I do not care to hear, "Oh, that's been tried, and it didn't
work."  Any comment with "they say" as its source does not impress me.
"Nothing else will work" is even less impressive, and "Nothing else will
work as well" is right in there, too.

It is a strange feeling, having in hand independently measured data
documenting the superior efficiency of an antenna, while the later results
of a respected engineer's computer study of the item, showing it to be
inferior, are published in a trade organization's handbook.  Been there,
and that's where I get my opinion on antenna modeling programs:  any good
one, properly handled, can give a good forecast of an antenna's
performance: but it will hardly be perfect, simply because we do not know
how to make the program perfect.  And that isn't at all considering data
entry selection problems.

A pleasant resetting of my registers once in a while is accomplished by
reading part of the oldest book in my radio library:  *The Principles
Underlying Radio Communication*, Prepared by the Bureau of Standards,
Revised to May 24, 1921, published by the USGPO for the US Army Signal
Corps.  The section on antennas is really something.  Based on the latest
engineering, experimentation, and practical experience, in light of today's
practices it seem almost comical.  Stuart Ballantine's breakthrough papers
were not seen until 1924; hence, in 1921, no one knew the advantages
offered by the quarter-wave antenna, much less anything taller.  And at
that time, in Laport's words, "Ground-system design was still in the
black-magic stage."  Yet many thousands of antennas had been built, they
were working, and radio was burgeoning.  The antenna experts knew all they
needed to know, and many thought they knew it all.  For what most of them
were doing, they were close enough.  But their knowledge wasn't optimized,
and it still isn't.

Reinvent the wheel?  Don't need to, don't want to.  I know what a wheel
looks like, what it does, and how it does what it does.  I'd like to invent
something that does the same thing except a lot better.  But if all I do is
keep on looking at wheels, I'll never get there.

I would appreciate being placed in contact with anyone who has actually
built and measured (in any reasonable way) the radiation performance of a
helical antenna fifty feet tall, seven to ten feet in diameter, with any
sort of identifiable ground system, operating on 1750M (or anywhere close
to those parameters).


SOME TECHNICAL STUFF:

I have argued with Doug DeMaw philosophically, but not technically.  He was
too good for that.  No one could find a better "cut and try" sort of
person.  So no way will I disagree with his statement that a
helically-wound vertical antenna needs about a half-wavelength of wire.
Doug, however, was talking about winding the turns *one wire diameter
apart* (and on a really slender form).  Pat Hamel's question was, instead,
about an antenna with much greater separation between turns.

Consider a quarter-wave tall wire antenna.  Step on it so that the wire
coils up as it is squashed.  At first, the resonance of the wire will
change very little, but as the coil is compressed more and more, the
resonant frequency will increase more.  Up to a point, of course.  But with
wide spacing between turns, there will be far less change in the original
resonant frequency as opposed the change experienced when the spacing is
much closer.  For a helix with wide turns spacing, a quarter wavelenth of
wire is a good start.  As the turns become closer, more wire will be
needed.  How much?  Beats me.  But I will rely on DeMaw:  when it gets down
to one wire diameter spacing, he says -- and I believe him -- about a
half-wavelength of wire will do it.


YET ANOTHER TRUTH OF THE UNIVERSE:

"Big low-loss coil" is an oxymoron.


To anyone who actually read all of this, thanks.

Regards,
John WA6QPL  AKA WC2XSR/5