Roy Lewallen wrote in message ...
Ok,

For anyone who cares, the magnitude of the current out of the inductor
in the later test measured 5.4% less than the current in. No phase shift
was discernible. An analytical person could build on this information to
investigate the properties of longer inductors placed elsewhere in the
antenna.

Thank you for the comments, Cecil, Yuri, Richards, Art, and others. I've
learned a good lesson from this -- that this isn't an appropriate forum
or appropriate audience for the sort of quantitative analysis and
reasoning I'm familiar and comfortable with. And that the considerable
time and effort required to make careful measurements is really of very
little benefit -- certainly not anywhere near enough to justify it.

Interesting though. I think I may try to rig up some couplers so I can
do this myself. I have the dual channel scope, but I need to build the
couplers.

With a great sigh of relief from everyone, I'm sure, I'll now turn this
thread back over to Yuri, Cecil, et al.

My apologies to everyone for taking up so much bandwidth.

None needed. If the group can have multiple postings on amateur
racists, and other assorted problem children, then I see no problem
with this thread, no matter how long it gets. So far, your tests,
while not being a bugcatcher type coil seem to match my expectations
fairly closely. I never expected to see no reduction at all. In my
view, even a large 75m bugcatcher coil is still a lumped coil, and
will pretty much act as one. Why do I think this? Because the overall
form is still very small per wavelength. IE: 90 degrees is appx 65 ft.
So far no one has argued that the current taper UNDER the coil is
suspect when modeled. Most all seem to agree that the current
distribution is dramatically improved when the coil is raised up the
mast. If you model a 10 ft whip, using a center load coil, the model
will show max current at the coil. Here is an example using eznec....

EZNEC Demo ver. 3.0

Vertical over real ground 11/12/03 11:30:20 AM

--------------- CURRENT DATA ---------------

Frequency = 3.85 MHz.

Wire No. 1:
Segment Conn Magnitude (A.) Phase (Deg.)
1 Ground 1 0.00
2 1.0013 -0.01
3 1.0036 -0.02
4 1.0072 -0.03
5 1.0122 -0.04
6 1.0192 -0.04
7 1.029 -0.05
8 1.0432 -0.06
9 1.0691 -0.06
10 1.1036 -0.07 ......coil is at segment 10
11 .98384 -0.07
12 .87242 -0.07
13 .77233 -0.07
14 .67604 -0.07
15 .58163 -0.07
16 .48789 -0.08
17 .3938 -0.08
18 .2982 -0.08
19 .19932 -0.08
20 Open .08787 -0.08

OK. Lets say the coil in the real world is one foot long. That is appx
1/10 of the total antenna length. Will there be any argument that max
current will occur at the coil? I hope not...
OK. Lets say that Yuri, et el, are correct and there is a noticable
taper of current across the coil from bottom to top. I still think
they are being fooled by the capacitance above the coil, which is
where they are testing, but thats another issue.
Say you have a 1 ft section of the antenna, "coil" and it is found
that there is a noticable current taper across it. What would this
amount to in the real world? To me, nothing much at all. I don't think
it would have any effect on the way I build mobile antennas. It won't
have any effect on where I mount my coil, because I am already using
the best locations possible. These "best" coil locations are old news
and easily calculated using a program such as Reg's "vertload" or even
info in the ARRL antenna handbook.
Would this current taper in a 1/10 section of the antenna drastically
skew any modeling done of this antenna? It's possible, but again, I
really doubt it.
BTW, I think I said earlier that the modeling of these mobile whips
didn't do a good job of showing increases in performance due to
changes in coil position.
But that seems to not be the case. I may have been thinking of
something else. I do show increases in gain when the coil is raised
from a base load, to a center load. As far as the reflected currents,
and phase, etc, I just don't see that causing a major difference in
the current across the coil. Some difference I'm sure, but I don't
think it would be enough to cause a difference in either the
calculation of best coil location, or in the modeling of the antenna.
I'm still of the opinion that if you measure the current at the top of
the coil, where it is attached to the capacitance section, this will
slightly stunt the upper coil measurement. The eznec plot *seems* to
agree. I'm still of the opinion that the current is *fairly* constant
across the coil, but I'm not losing any sleep over it. I'll still be
building my antennas the same way I have been. Nothing will change,
even if it's determined they are correct about this current taper
across the coil. MK