"Roy Lewallen" wrote in message
...
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
Oooops, carefull here.
As far as I know, nobody has claimed that inserted loading coil replaces the
"missing" degrees of the radiator in terms of providing magical properties
that would look like that "replaced" portion of the antenna, or make the
antenna act like 90 degree full size physical radiator.
What we are saying that the loading coil appears to replace "missing"
electrical degrees of the radiator in order to make it resonant, that is
back to 90 electrical degrees (has to be in order to resonant), which rest
of the existing "straight" radiator forces it to do (+/-). Radiation
properties and efficiency of the loaded antenna is proportional to the area
under the current curve. It is obvious to anyone comparing the area under
the current curve of full size quarter wave radiator vs. loaded radiator
that there is huge difference in area under the curve and performance,
efficiency, which is known and been verified by numerous measurements.
HOW the current curve is modified by different loadings and position along
the radiator is important in knowing how the current distribution curve
along the radiator is modified.
The whole controversy is that "gurus" claim current doesn't drop across the
coil, while we say that it does, therefore making the area under current
curve above the coil smaller and effciency of loaded antenna worse than they
believe and insist on.
Again, when applied in modeling programs, wrong assumption will produce
erroneous results, which will be magnified in multielement antenna designs.
So the "gurus" basically ignore behavior of coil in the standing wave
environment along the loaded radiator, where the current drops from max at
base to zero at the tip, but coil would magicaly resist that, because, bla,
bla, bla.... (see their "reasons")
So while everyone knows (?) that standing wave current drops acros (along)
the wire (all the antenna books show that), but it is "impossible" to drop
along the coiled wire (real inductance - coil, loading stub). Reality and
measurments prove that, but according to them "it can't be so".
I am already gathering necessary hardware to do more experiments,
measurements to show what is really happening, and will prepare articles how
to model and apply it to antenna design.
I would challenge the "unbelievers" to join me and repeat the tests, to see
wasaaaap.
73 Yuri, K3BU