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

"Mark Keith" wrote in message
om...
So far, your tests,
while not being a bugcatcher type coil seem to match my expectations
fairly closely.

I'd like to hear an explanation for ANY current difference across a coil
that is supposedly behaving as a lumped inductor. But the test really
should be for the same type of antenna used in Yuri's discussion; A
physically short antenna, with an electrically long coil, positioned away
from the feedpoint. One misconception here has been about the physical
length of the coil with respect to wavelength. That's not the most relevant
issue, in my opinion. The wire comprising the coil also has a physical
length. The relationship between physical length and electrical length is
velocity factor. The same thing is true for a coil. The velocity factor
for a wire does not go to infinity simply by virtue of the fact that it has
been wound into a coil. This is basically what is being implied when
someone argues that loading coils do not effectively supliment the
electrical length of an antenna.

73, Jim AC6XG

Jim Kelley wrote:

I'd like to hear an explanation for ANY current difference across a coil
that is supposedly behaving as a lumped inductor. But the test really
should be for the same type of antenna used in Yuri's discussion;

Jim, did you fail to notice that arc-cos(0.95) = 18.2 degrees?
--
73, Cecil http://www.qsl.net/w5dxp



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Cecil Moore wrote:

Jim Kelley wrote:

I'd like to hear an explanation for ANY current difference across a coil
that is supposedly behaving as a lumped inductor. But the test really
should be for the same type of antenna used in Yuri's discussion;

Jim, did you fail to notice that arc-cos(0.95) = 18.2 degrees?

No. But I have failed to notice any explanation for it other than you
and Yuri have provided.

73, Jim AC6XG

Jim Kelley wrote:

Cecil Moore wrote:
Jim, did you fail to notice that arc-cos(0.95) = 18.2 degrees?

No. But I have failed to notice any explanation for it other than you
and Yuri have provided.

Assuming the forward current and reflected current are in phase
at the feedpoint, the 5% reduction in net current at the other
end of the coil appears to be because the forward current and
reflected current are not in zero phase at that point. The phase
of the forward and reflected currents are changing in a predictable
manner but the phase of their sum, the net current, doesn't change
much if they are in the ballpark of the same magnitudes. I think Roy
measured that net current phase.
--
73, Cecil, W5DXP

Mark Keith wrote:
So far, your tests,
while not being a bugcatcher type coil seem to match my expectations
fairly closely.

They seem to have matched Yuri's predictions almost exactly. He predicted
a 5% reduction in current. That was very close. He predicted an 18 degree
effect. Turns out a 5% reduction in current in that area of the cosine
curve is almost exactly 18 degrees. Cos-1(.95) = 18 degrees
--
73, Cecil http://www.qsl.net/w5dxp



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On 12 Nov 2003 10:03:40 -0800, (Mark Keith) wrote:

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...

Hi Mark,

I offered an EZNEC analysis that supported (circumspectly) Yuri's
position, but he blew it off chasing rainbows. Using the protocol
(already published by Yuri) for emulating a solenoid (and not just the
contentious one point load), that solenoid is found residing on
segments 50 to 59 (spanning 10 inches):
1 W2E1 1 0.00
2 .95623 0.00
3 .9205 0.00
4 .88976 0.00
5 .86122 0.00
6 .83415 0.00
7 .80815 0.00
8 .78296 0.00
9 .75843 0.00
10 .73443 0.00
11 .71088 0.00
12 .68771 0.00
13 .66486 -0.01
14 .64229 -0.01
15 .61997 -0.01
16 .59787 -0.01
17 .57596 -0.01
18 .55421 -0.01
19 .53261 -0.02
20 .51115 -0.02
21 .48979 -0.02
22 .46853 -0.02
23 .44736 -0.02
24 .42627 -0.02
25 .40523 -0.02
26 .38424 -0.02
27 .36329 -0.02
28 .34238 -0.03
29 .32148 -0.03
30 .30059 -0.03
31 .27969 -0.03
32 .25878 -0.03
33 .23785 -0.03
34 .21688 -0.04
35 .19585 -0.04
36 .17477 -0.04
37 .1536 -0.05
38 .13234 -0.05
39 .11095 -0.06
40 .08941 -0.07
41 .06769 -0.08
42 .04576 -0.12
43 .02355 -0.21
44 .001 -4.38
45 .02202 -179.8
46 .04579 180.00
47 .0707 180.00
48 .09404 180.00
49 .11529 180.00
50 .13404 180.00
51 .14984 180.00
52 .16235 180.00
53 .17155 180.00
54 .17718 180.00
55 .17057 180.00
56 .15943 180.00
57 .15069 180.00
58 .1433 180.00
59 .13668 180.00
60 .1306 180.00
61 .12495 180.00
62 .11962 180.00
63 .11457 180.00
64 .10975 180.00
65 .10512 180.00
66 .10066 180.00
67 .09634 180.00
68 .09216 180.00
69 .08809 180.00
70 .08413 180.00
71 .08025 180.00
72 .07646 180.00
73 .07274 180.00
74 .06908 180.00
75 .06549 180.00
76 .06194 180.00
77 .05845 180.00
78 .05499 180.00
79 .05158 180.00
80 .04819 180.00
81 .04484 180.00
82 .0415 180.00
83 .03819 180.00
84 .03488 180.00
85 .03159 180.00
86 .02829 180.00
87 .02499 180.00
88 .02167 180.00
89 .01831 180.00
90 .01491 180.00
91 .01141 180.00
92 .00777 180.00
93 Open .00363 180.00

I will note a caveat that it does not prove anything by Yuri's source
of information, and as Yuri is admittedly ignorant of the details of
the physical model, I was forced to guess the model specification by
the inference of the commentary at his page, and the attending
photographs. Further, contrary to what was said, neither is it
resonant (a fact that Yuri offers no amplification too, amending data,
or confirmation nor denial), About the only thing that can be said:
"the solenoid offers a current differential."

73's
Richard Clark, KB7QHC

Richard KB7QHC wrote:

I offered an EZNEC analysis that supported (circumspectly) Yuri's
position, but he blew it off chasing rainbows.

I am terribly sorry, with all the mumbo-jumbo going on I didn't see the right
rainbow over the devils :-)

I have to go back and reread the thread (take a vacation :-), I guess some of
the points obvious to me that were nit picked blinded me over the diamonds
hidden. The confusion was that all I had on the W9UCW set up was what I had
published, and you assumed that was my setup/data and kept asking me about it.

I will be making snap-on current probe, which will make it easier to slide
along the element and observe the current without the disturbance to the
antenna and will be a bit different over the thermocouple meters. Just need a
bit more time.

Thanks to all those civil pros and cons, looks like we are getting ahead. If we
can implements the phenomena properly in modeling software, it should be giant
step in properly analyzing and designing loaded antennas and elements. There
are many dBs hidden there.

Yuri, K3BU/m

On 12 Nov 2003 21:23:21 GMT, oSaddam (Yuri Blanarovich)
wrote:

Richard KB7QHC wrote:

I offered an EZNEC analysis that supported (circumspectly) Yuri's
position, but he blew it off chasing rainbows.

I am terribly sorry, with all the mumbo-jumbo going on I didn't see the right
rainbow over the devils :-)

Hi Yuri,

It's fine by me to be compared to devils (munchkins in comparison to
their satanic majesty).

I have to go back and reread the thread (take a vacation :-), I guess some of
the points obvious to me that were nit picked blinded me over the diamonds
hidden. The confusion was that all I had on the W9UCW set up was what I had
published, and you assumed that was my setup/data and kept asking me about it.

If you quote a source, you are responsible for the outcome of its
challenge. It is not up to the challenger to chase down the
problematic details, and it is not your defense to say the other guy
got it wrong.

The question that leaps to mind is how are you going to replicate the
data if you were so ignorant of the original details? Even more, it
would further all discussion for you to offer a COMPLETE specification
of what you are doing (or going to do), rather than an informal ramble
around the garden with a camera.


I will be making snap-on current probe, which will make it easier to slide
along the element and observe the current without the disturbance to the
antenna and will be a bit different over the thermocouple meters. Just need a
bit more time.

This is responsive to my issue with heat - through substitution. It
doesn't completely answer it, but the data is the focus and the
reduction of error is a goal.


Thanks to all those civil pros and cons, looks like we are getting ahead. If we
can implements the phenomena properly in modeling software, it should be giant
step in properly analyzing and designing loaded antennas and elements. There
are many dBs hidden there.

Yuri, K3BU/m

73's
Richard Clark, KB7QHC

Richard,
If your current is different at the ends of the coil, you're an angel.


The question that leaps to mind is how are you going to replicate the
data if you were so ignorant of the original details? Even more, it
would further all discussion for you to offer a COMPLETE specification
of what you are doing (or going to do), rather than an informal ramble
around the garden with a camera.

The point of the original argument was: is the current the same or different at
the ends of the typical coil in loaded antenna. I will reiterate the exercise:
I knew it was different from my "heat tests with Hustler", W8JI countered "you
dummy, it can't be" (in a nutshell :-), ON4UN showed graphically how, W9UCW
chimed in "it is, I measured it, here is some data", Cecil theorized it, W8JI
chorus "calculated" it can't be.

My point is that I argued that current is different, not how precisely I can
calculate or offer calculated "proof", the first order was to convince
unbelievers that there is a difference and let them loose to figure out why
(Cecil shined light on it) and then to properly apply formulas and figures so
we can model it.

So when I say that I want to do MY measurements, I am not after exactly
duplicating W9UCW measurements and test, I just want to pick, first my mobile
antenna (practical situation) and then similar setup what Barry used - nice 60
radial ground plane and various loaded radiators and see what (formulas,
software) comes close to reality. We are already seeing some path, and with
sliding current probe I believe I can get more data along the radiators and we
can see how does it jive with Barry's and with calculations and modeling. So
again, I am not after replicating Barry's laboratory. If what we are saying is
true, than it doesn't matter how fat the coil is, where it is within the
limits, more data from various situations will help us to correlate the
procedures. My goal was to convince unbelievers (and as we can see, there are
plenty), well, to show that current in a typical loading coil's ends IS
DIFFERENT (it is up them to believe it or not).

This wasn't on the level of scientific conference paper, but more like a street
fight - who is right and why are you ridiculing me (us) if I am (we are) right.
Now roll your slide rule blades out and lets do the stage two, fine tune the
"theory" and put some good numbers on IT.

So she's round after all? Should we change thread name now?

Yuri, K3BU.us