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Re: [TowerTalk] "Magic antenna" from Vincent at URI

To: <towertalk@contesting.com>, "Barry Johnson" <barry@w4wb.com>
Subject: Re: [TowerTalk] "Magic antenna" from Vincent at URI
From: "Tom Rauch" <w8ji@contesting.com>
Reply-to: Tom Rauch <w8ji@contesting.com>
Date: Tue, 17 Aug 2004 08:38:01 -0400
List-post: <mailto:towertalk@contesting.com>
> Did anyone go to Boxboro and hear the 2-hour talk that was
to have been
> given by Vincent on his new antenna design?

It's my understanding (based on an e-mail from someone who
did go to Boxboro) that the "new design" is nothing more
than an attempt to make current uniform over the largest
possible area of antenna by fooling around with loading coil
placement.

This is something that is better accomplished by using a
capacitance hat.

If you have a very thin base loaded very short radiator,
current will taper in a triangular distribution. If you have
a radiator with all the capacitance at the very end, current
will be uniform. You can do the something similar by moving
a loading coil around (which is what Vincent did), but it
won't be quite as effective.

The difference between those the base- and end-loaded
perfect extremes is a four-fold increase in radiation
resistance, which is exactly the same as produced by
doubling height of a triangular current distribution short
vertical. In the real world all short antennas fall between
these extremes.

This is a long way of saying "it's nothing that hasn't been
accomplished more effectively in the past by other methods".
There isn't any magic, this stuff was all resolved in the
1900's and earlier.

73 Tom


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