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Lattin antenna.............more info sources
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April 19th 04, 06:22 PM
Richard Clark
Posts: n/a
On 19 Apr 2004 05:14:44 -0700,
(N2EY) wrote:
Why a stub that is excited
along its length should behave as a trap is not explained, nor how the
shortened sections act as loading coils (the entire antenna is only
112' 4" long, plus connections).
Hi Jim,
Simply because the so-called explanations are more wish than reality.
I've not slackened my study of this design. I've done thirty or forty
measurements that have interest in their own right, but show the
"theory" is sheer fantasy. These notions of tuned stubs as traps are
so far off the mark in practice that no one notices they don't make
sense electrically either.
Modeling the thing looks like a real challenge for a whole bunch of
reasons. The gaps between sections may be important, for example.
....
I suspect that a key element to the antenna's operation is the use of
the tubular Twin-Lead, with its 0.8 velocity factor. This stuff is
probably close to being unobtanium these days. Another point is the
extreme narrowness of resonance on most bands.
These apologies ring false. The issue of gaps is desperate and the
selection of tubular has no basis in special characteristics. All
such considerations MUST yield to simple scaling. For instance, if
you need 0.8 and have 0.9, there is no magic formula beyond
proportions necessary to achieve "what should be."
The difficulty lies in the supposed explanations.
The W5GI antenna seems to be a variation on the Lattin theme.
And it is even more gauche. It approaches antenna design as an allied
art of Palmistry.
73's
Richard Clark, KB7QHC
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