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Old April 12th 06, 04:06 AM posted to rec.radio.amateur.antenna
Roy Lewallen
 
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Default Current across the antenna loading coil - from scratch

Mike Coslo wrote:
Yuri Blanarovich wrote:
Check my article that describes the controversy, shows some proof of
reality and then efforts of the "gurus" to deny it and "reason" why
it can't be so. http://www.k3bu.us/loadingcoils.htm The problem is
that back in 1953 in QST article there was erroneous
conclusion/statement made, which propagated through the books, until
W9UCW measured the current across the loading coils and found that
there is significant drop from one end to the other, and the rest is
(ongoing) history


Hmm, certainly it would seem to make sense that:

The current in a typical loading coil in the shortened antennas drops
across the coil roughly corresponding to the segment of the radiator
it replaces.


Quote from your page.

I would not expect anything else. If the loading coil is making the
antenna act like a physically longer antenna, other "qualities" of that
simulation are likely to be similar.

Is there a reason why the coil would *not* do this?


Yes, many, and they've been discussed here at length. That this concept
is wrong can and has been shown by theory, modeling, and measurement. I
made and posted measurements on this newsgroup in November 2003 which
demonstrated clearly that the presumption is false.

The loading coil isn't making the antenna act like a physically longer
antenna. In the extreme case of a physically short inductor at the
feedpoint, it's simply modifying the feedpoint impedance and has no
effect whatever on the antenna's radiation. As the inductor gets longer,
it does become some part of the antenna, but adding an inductor which
resonates, say, a 45 degree physical radiator doesn't make the antenna
act like a 90 degree physical radiator.

Roy Lewallen, W7EL
 
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