Doug, you have to include "amps" in the question...like, um...if I build the
Wonder Bar antenna how much power will it handle?
:-)
I looked at the article and think the author's heart was in the right place
but I never would have accepted such an article for publication. He did not
show a close-up of the loading/matching coil system, and the little photo
that was there isn't very good nor very instructive. A hand-drawn diagram
would have been much better. He also went on to say how interactive the
tuning is (sliding the link coupling back and forth, shorting out turns,
etc, etc) but then didn't actually detail the result of all that
experimentation with any specificity. The fact is, if anybody used the same
element lengths he did, they should end up using the same coil and link
system for optimum results. Once the experimentation is done on the
prototype, there's no reason that everyone should have to do the same
experimenting.
He also mentioned something about copper tubing being just slightly heavier
than aluminum. Hmmm. That's not quite right, it's a lot heavier and
actually not as strong.
Looks like an interesting approach to low-profile antenna construction,
yielding a light weight, low-load antenna that probably has 3-4 dBd gain.
But since I have heavy duty rotators and a tower, I wouldn't go out of my
way to build a small, lightweight 17m beam. It's probably a slick idea for
somebody trying to be "stealthy" and put up something that looks a lot like
a TV antenna.
73
Steve WB2WIK/6
-----Original Message-----
From: Doug [mailto:dcoffman@iquest.net]
Sent: Monday, December 18, 2006 1:16 PM
To: amps@contesting.com
Subject: [Amps] QST Jan 06 (Off topic)
All,
This is off topic for this group, however what is the consensus of the 17
meter "Wonder Bar" antenna?
>From a stand point of low wind load and some directivity, this looks like a
good project for my QTH. I do have questions concerning tuning and spacing
of
the elements.
First off, is this beam actually worth building?
I own the MFJ 249 (pre B version) and a Grid Dip Meter. I would like to
better
understand how to tune the elements for resonance.
There were no formulae given or stated for construction of this beam or
construction of a similar beam on another band. A Google search did not
yield
much information. I was contemplating ordering the older QST articles that
were referenced.
73,
Doug - N9XTF
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