Current across the antenna loading coil - from scratch
 

John Popelish wrote:

Cecil Moore wrote:
What does it mean to the E-fields and H-fields to say
the voltage is leading the current?

It means that the current at both ends of the coil was delayed (relative
to its phase if the coil had not been there). It means that there was a
voltage difference across the ends of the coil that drove that current
through the coil.

In order to avoid any delay through the coil, you propose a delay
in the one inch of wire at the bottom of the coil? Does that really
make sense to you? How is this magic delay accomplished?
--
73, Cecil http://www.qsl.net/w5dxp

Current across the antenna loading coil - from scratch
 

Gene Fuller wrote:
You spent a lot of time developing the "10 degree" model for the
bugcatcher coil.

Yes, it was a waste of time since I didn't accomplish the
goal of eliminating reflections. The phase angle between
the source voltage and source current is 71 degrees. That
proves that I failed to eliminate reflections.

You keep referring everyone to the now famous gif image on your web
page. The question becomes why is EZNEC correct in supporting your
position at some times and incorrect when it does not support your
position at other times?

EZNEC doesn't differentiate between standing waves and traveling
waves. The user has to ensure there are no reflected waves. I
failed in that task. It's no big deal. I fail quite often.

My position is technical facts and accuracy. What is your
position?
--
73, Cecil http://www.qsl.net/w5dxp

Current across the antenna loading coil - from scratch
 

K7ITM wrote:
Like I posted earlier today, Tom, all of this provides an interesting
window into Cecil's mind.

Tom, I find it strange that you are defending your violation
of newnews attribution guidelines. What other unethical
activities do you defend?
--
73, Cecil http://www.qsl.net/w5dxp

Current across the antenna loading coil - from scratch
 

Cecil Moore wrote:
John Popelish wrote:

Cecil Moore wrote:

What does it mean to the E-fields and H-fields to say
the voltage is leading the current?


It means that the current at both ends of the coil was delayed
(relative to its phase if the coil had not been there). It means that
there was a voltage difference across the ends of the coil that drove
that current through the coil.


In order to avoid any delay through the coil, you propose a delay
in the one inch of wire at the bottom of the coil? Does that really
make sense to you? How is this magic delay accomplished?

Exactly the way it is accomplished if you apply AC to an LC "L" low
pass filter that droves a resistor load. The short antenna acts as
the capacitor (in parallel with losses and radiation) in the circuit.
It is resonated with the series inductor so both the inductance and
capacitance cancel, so the source drives only the losses and
radiation. Power factor corrected.

If you don't believe me, simulate it with EZNEC. Connect a source to
a parallel combination of C and R. Record the phase of the current
with respect to the voltage (the current will lead). Then add a
series inductance that cancels the capacitance, and the current will
be delayed till it matches the phase of the applied voltage. Power
factor corrected.

Current across the antenna loading coil - from scratch
 

Cecil Moore wrote:
Yuri Blanarovich wrote:
What we are saying that the loading coil appears to replace "missing"
electrical degrees of the radiator in order to make it resonant, ...

W8JI says we are correcting the power factor. Every EE knows that
correcting the power factor involves shifting the phase, i.e.
the coil cannot correct the power factor without providing a phase
shift.

This is another area where you fall right square on your face.

An inductance changes the relationship between phase of voltage and
current, NOT current through the inductance from terminal to terminal.

You either know that and are intentionally avoiding it to save face, or
you need to brush up on basic theory.

The whole controversy is that "gurus" claim current doesn't drop across the
coil, while we say that it does, ...

Yuri again distorts fact. What everyone is saying is there can be a
current change, but it is not caused by standing waves or missing
antenna area. It is caused by displacement current, and so can have a
wide range of change in a given antenna.

Please write that down Yuri, and keep it in front of you so you don't
forget again!

73 Tom

Current across the antenna loading coil - from scratch
 

On Wed, 12 Apr 2006 21:01:25 GMT, Cecil Moore
wrote:

Richard Clark wrote:

Cecil Moore wrote:
It doesn't cost anything to be paranoid. :-)

You must have a Xerox bulk copy rate.

I got a free printer with my new Dell computer.

Now you need a free scanner, and you are truly paranoid by your own
tally.

Current across the antenna loading coil - from scratch
 

"Roy Lewallen" wrote in message
...
Yuri Blanarovich wrote:

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.

Agreed, it's not quite stated as such. Here are some statements which were
made:

From your web page http://www.k3bu.us/loadingcoils.htm, in bold type:

"In summary:
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."

By Cecil, on March 5, on this newsgroup:

"A loading coil thread is climaxing over on qrz.com. I have
used EZNEC to generate a graphic which shows a 3/4WL vertical
and a similar 1/2WL vertical with a ~1/4WL loading coil. The
loading coil is a wire helical coil containing (surprise)
roughly 1/4WL of wire. The coil does a good (not perfect)
job of replacing 1/4WL of wire. Many things can be gathered
from observation of the current reported by EZNEC for the
two antennas. The coil occupies roughly the same number
of degrees of the antenna as the wire it replaces. The
current at the top and bottom of the coil is roughly the
same as the current at the two ends of the wire it replaces.
Is the coil an exact replacement? Of course not."

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 (+/-).

It's getting muddier and muddier just what you mean by "replace". Nobody
has questioned that a loading coil makes the antenna resonant; that's its
purpose. But that's simply an impedance transformation property which can
be accomplished well away from the antenna by many different methods.


Roy,
the above are the attempts to illustrate and add some more to understanding
and reasoning why the current across (alonng) the loading coil, roughly half
way or 2/3 up the resonant quarter wave radiator is larger at the bottom and
drops about 40 - 60% at the top. While one side argues that it is (almost)
the same, we argue that it drops. That is the argument and not detours to
degrees, phasors, and rest of the mud that was rehashed here.

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.

I agree with all this. I'm glad you've clarified this for the benefit of
posters like the one to whom my recent posting was directed.

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.

I don't think you'll have any trouble winning your arguments against your
imaginary "gurus", whomever and whatever they might be. Over two years ago
I made careful measurements which showed a current difference between the
top and bottom of a loading coil. Cecil posted an EZNEC model on his web
site showing a substantial difference. I've commented on it several times,
explaining the reason for the difference, and modifying the model to
illustrate the explanation.

If I remember correctly you inserted the coil at the base and I am not sure
if it was resonant quarter wave radiator. Can you describe the setup, length
and frequencies used? You should try to use quarter wave resonant radiator
with coil about 1/2 to 2/3 up the mast and tell us what the current values
are. W9UCW has pictures and data measured, we should try to emulate this
situation, that is the object of controversy. Cecil mentioned cases when
current can be the same, or lower at the top, or bottom, depending where the
same coil is placed in relation to the standing wave and current
distribution on the radiator. Are you denying that this is the case or
something wrong with W9UCW test setup and results?

The controversy is in the explanation of the difference. It simply doesn't
require Cecil's theories. I've never been able to tell exactly what your
theory is, if you indeed have one.


The controversy is about the claims that the current at the ends of the
typical loading coil is the same or different in range of 40 -60% drop. Its
not my theory, it is the reality that we are trying to bring forth and
correct misconceptions that are obviously floating around since 1953. My
approximation and explanation (latest) I mentioned is in one of my posts in
reply to W8JI "arguments" (to do with impedances).

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")

Would you name these "gurus" so we can read their postings and see what
you're talking about?

Mostly the "equal current camp".

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.

You'll be surprised when everyone agrees that there's a current difference
between the top and bottom of the coil. Unless your "gurus" show up,
whomever they are.

I've already made a test and posted the results, over a year ago. When it
failed to show a current difference anywhere near the number of degrees it
"replaced", your complaint was that I was using an inductor which was too
small physically. So obviously your theory works only on certain size
inductors. Once you or Cecil has the theory fully worked out, it should be
able to not only tell us what the current difference between top and
bottom should be, but also how physically large an inductor must be before
the theory works. And why it doesn't work for physically small inductors.

I have not verified it, but W9UCW claims using ferite inductor and got very
similar results. I believe your test, you used coil near the base. I will
run test with different inductors from bugcatcher type, "no good" Hustler,
to ferite and in different positions.

Those of us stuck with old fashioned conventional theory can explain the
drop for small as well as large coils, so you folks have a bit of catching
up to do.

Looks like the size of the coil has small effect on current variation
(unless high resistance). Position of the coil in relation to current
distribution along the radiator would cause equal (special case), less on
the top of coil or more, depending where on the standing wave curve coils is
located. In our case we are arguing about 2/3 up the resonant radiator.

I think a lot of the experimental work can be done by modeling. I'd be
interested in hearing of any cases where measured results differ
significantly from EZNEC results. Incidentally, your web page is a bit
outdated in that respect, apparently being written before EZNEC v. 4.0 was
available with its automated helix creation feature.

Now with solenoid generation in EZNEC 4.0 it helps to get away from the
lumped inductance and it shows that there is current drop, reflecting
situations in question. Also the loading stub produces similar results.
Cecil showed the cases and with different positions along the current curve,
demonstrated in EZNEC huge differences in current at the ends of the coil.
But this is getting strangely ignored and instead we get all kinds of
"reasons" why it can't be.
I am sorry I dropped out of this due to AOL dropping NG, and I thought that
reality would be understood by now. Only when Cecil told me that subject
flared up again and nothing changed, I rejoined the discussions. I think
really at this point, it is beating the dead horse. I will do the tests and
write it up. I will try to corellate the tests with modeling in EZNEC. If
someone denies the reality, that's their choice. I will post the progress on
my web page.
I can't stomach W8JI "exchanges" any more. No answer to questions or
following the points, just twist and jive.

Roy Lewallen, W7EL

I didn't look it up, but is there way in EZNEC to know or calculate the
inductance of modeled solenoid? Or better, specify the inductance and let
the EZNEC "make" the coil of prescribed diameter and TPI?

73, Yuri Blanarovich, K3BU

Current across the antenna loading coil - from scratch
 

David G. Nagel wrote:

Wes Stewart wrote:


Responding to no one in particular.

This is starting to make me miss the shorter Fractenna threads.
Phil, comeonback good buddy.



They certainly made more sense.

Dave N

Although there is a large difference - this is an arument over how
soemthing that works works. The other was about _whether_ the thing works.

tom
K0TAR

Current across the antenna loading coil - from scratch
 

John Popelish wrote:
If you don't believe me, simulate it with EZNEC. Connect a source to a
parallel combination of C and R. Record the phase of the current with
respect to the voltage (the current will lead). Then add a series
inductance that cancels the capacitance, and the current will be delayed
till it matches the phase of the applied voltage. Power factor corrected.

The "current will be delayed"? That cannot be, according to
W8JI and W7EL. They say there is no more delay through a 6"
coil than through a 6" wire. That's what the argument is all
about. Instead of the current being delayed, their voltage
jumps ahead in time at greater than the speed of light in
order to correct that power factor.
--
73, Cecil http://www.qsl.net/w5dxp

Current across the antenna loading coil - from scratch
 

Cecil Moore wrote:
John Popelish wrote:

If you don't believe me, simulate it with EZNEC. Connect a source to
a parallel combination of C and R. Record the phase of the current
with respect to the voltage (the current will lead). Then add a
series inductance that cancels the capacitance, and the current will
be delayed till it matches the phase of the applied voltage. Power
factor corrected.


The "current will be delayed"?

Compared to the phase of the current without the inductor being in
series."

That cannot be, according to
W8JI and W7EL. They say there is no more delay through a 6"
coil than through a 6" wire.

You are talking about delay from one end of the coil to the other. I
am talking about delay, compared to the same circuit without the
inductor in place. See the difference?

That's what the argument is all about.

Not from where I am watching.

Instead of the current being delayed, their voltage
jumps ahead in time at greater than the speed of light in
order to correct that power factor.

Good one. Pull the other.