wrote in message
ups.com...
but we can not
use electrical degrees to 'splain the behavior of coiled antenna wire?

I can see how problems could arise going by the length of coil
wire length in degrees only. Lets say you run a coil 1 foot from the
base. Lets say that coil uses 25 turns to tune a particular frequency.
Now, move the coil up 2 ft higher, and see if that same 25 turns will
tune the same frequency. It won't. You will have to add a few more
turns.
So just going by the total mast plus coil wire length in degrees could
vary
all over the map just by changing the position of the coil. As you
raise
the coil, you will have to add more and more of "degrees" of wire to
tune the same frequency. :/
Dunno...There may well be some variation of current from the bottom
vs the top of the coil, but overall, I still view the operation of a
loading
coil as a "lumped" mechanism overall.
Even if you all decide that the current changes, or it doesn't , it
ain't
gonna make a hoot's worth of difference in the design of mobile whips.
I think it's an argument that has no real value to me as far as mobile
whips go. The performance of all the various coil heights, and configs
have been well known for years. Coil current taper or not.
I just don't see the facination with arguing about something that even
if
decided one way or the other, still won't make any difference in the
final
antenna design. Oh well...Continue the tail chasing excercise....
I'm outa this one... One post is all I will waste on this subject..
I couldn't mount my coil much higher if I wanted to... Current taper or
not. :/
MK


MK, that is the whole point, that you portray missing or not appreciating.
It might not matter to you if you lose $100, but it might matter to someone
else. Same with loading coil. What you are describing, the effect where the
coil is located, being known, is the result of the phenomena we are trying
to straighten out, explain and apply properly in modeling and design
exercises.

The position of coil within the antenna has significant effect. The worst is
at the base, fewer turns required. The best is somewhere about 2/3 up the
radiator, more turns required. You stick it on the top, no stinger or hat,
you get it almost invisible. With what we are discussing and defending here
is the proper understanding of the current flow in the loading coil and its
drop across and its effect on the efficiency of the loaded antenna.
Efficiency is proportional to the area under the current curve distribution
along the radiator. If you properly model the coil as solenoid or loading
stub to see the real drop of current across the coil and its effect in
various positions along the radiator, the all is clear and is with agreement
with practical experience, antenna shootout results, measurements.
As I mentioned numerous times, its effect on design and modeling loaded
antenna systems will be even more pronounced, because effect gets magnified
when you start adding elements. This is especially important when you try to
design super receiving antennas for low bands where F/B and clean pattern is
very desirable and is the most critical aspect of antenna design or
modeling. It is harder to obtain the max F/B or least rear lobes than to
maximize the design for max gain.
It might not matter to you, but I am sure many would benefit from knowing
more precisely what is REALLY going on and then use or correct their design
methodology.
I think it is fine for you to ignore this and poh-poh it. But I know how
huge difference it made in my 160m mobile antenna when I extended the whip
to the front bumper with wire.
We are not saying that piece of wire that coil is wound with, has so many
electrical degrees. If we carefully consider and understand the phenomena,
you would realize that the radiator has same electrical length (say 15 deg)
and when you move the coil and ADJUST THE TURNS to bring the antenna back to
resonance (90 deg) that coil would "replace, take care of" 75 degrees. The
turns have to be adjusted in order to "participate" in the current
replacement game. The lesson is, the higher you place the coil on the
radiator, the more turns you need to reresonate the radiator, the high
current portion of the antenna current distribution curve gets "stretched
up", better efficiency (larger area under the overall curve). Then the coil
DROPS the current across itself to some lower value, which then continues to
drop across the tip and that area, quite smaller adds to the one from the
bottom part of the radiator.
This all is supported by reality, except "gurus" who insist that the current
is (about) the same across the coil and they make (theoretically) antenna
current to be higher across the tip and "more" efficient than it is. Again,
you stick 6 of those in the 3 el loaded Yagi design and you get GI-GO.

It is known how profound effect had replacement of loading stubs by coils in
the KLM 3 el. 80 m loaded Yagi. Better gain, huge improvement in the F/B and
pattern. Has been done and described. And this is just replacing the same
inductance value stub with coil, where delta current from stub wires was
enough to throw monkey wrench in the Yagi performance. Now consider larger
error from the wrong assumption or calculation caused by wrong current
magnitudes and distribution.

Again you might not give a hoot about this "trivial" exercise, but if I want
to design 4 el loaded quad or Yagi for 80 or 160, it matters a lot.
So it just amazes me that some of the smarter heads resist so much in trying
to find out reality and develop better consideration of the effect for
design and modeling. No technical answers to Cecil's questions and my "from
scratch" thread deteriorated into pink electrons and dead end in electrical
degrees.

So far what we have is the reality, few who are trying to legitimize it and
few who got off on the wrong foot, in effort to preserve their (wrong) face
they cling to it with scientwific "proofs" why it can't be so, when IT IS.
When I tried to go step by technical step through the case, the "gurus" are
not there. Cases that Cecil showed in EZNEC model and demonstrating that
current across the loading coil (not one in the box) in the antenna can have
anything from equal to "nothing" at the other end, depending on its position
in the standing wave picture. It all jives with our original argument. We
spotted the "problem", we dissected it, thanks to fierce flat earthers, and
now have better understanding of the phenomena and can use to design better
antennas.
I care about antennas, this is the last frontier where we can still improve
thing, now with modeling tools. I still operate contests and go for
ultimate - beating the all time records, and that's where the edge can be
obtained.

Heloooo guys!
Measure, feel, whatever, the frickin' current across the loading coil and
then come back and tell the world why it IS different, but IT CAN'T be so,
because you said so in the beginning and you just can't admit being wrong.
Reality can't be twisted, just like Earth is not going back to flat!
Saying now that is no big deal, not important, will not exonerate the
"wrongoes". It is significant not to be ignored. If I was in "their" shoes,
I would say: "gee guys, interesting, thanks for bringing it up, explaining
it, I guess we were wrong, now we can design better antennas". Stay
tuned.....

Thanks again Cecil, Richard and others for putting up with and shedding more
and more light on the phenomena. It must go down in history as big as
Galileo's fight :-) I am glad that, hopefully, nobody will burn us.

73 Yuri, K3BU.us