Current through coils
 

Gene Fuller wrote:
I am quite sure I did not take any "side" in this topic.

I assume you are on the side of technical facts as am I.

I believe in
lumped circuit models, and I believe in network models. My aim was to
try to correct some of the basic math and physics flaws, not to argue
over the exact regimes of applicability for lumped and non-lumped models.

Your func(kx)*func(wt) Vs func(kx +/- wt) posting contributed a
good deal of technical accuracy to the discussion and I thank
you for that.

At the same time, if proving your "side" includes mobile antennas with
48 foot whips ... then please leave me off of your "side".

And there's the blind spot. The two antennas are identical except
for the 40 foot extension. The coil doesn't know the extension
is there. Why did the slope of the current taper reverse between
those two configurations? How does the lumped-circuit model explain
more current "flowing" out of the top of the coil than is "flowing"
into the bottom of the coil? It's a simple question but the answer
has been conspicuous by its absence. I will keep asking that question
until someone answers it.

The distributed network analysis handles both of those configurations
in a valid way. Adding 40 feet to an antenna is no problem. The relative
phases of the forward and reflected currents changed - that's all that
happened.

But by adding 40 feet of wire to the antenna, the lumped circuit analysis
falls completely apart. So how do we know it was valid for the 8 foot
antenna where everything is the same except for length? We don't!

Since the lumped circuit analysis falls apart by adding 40 feet to an
antenna, I contend that the lumped circuit analysis fell apart with the
8 foot antenna but you guys don't realize it yet.
--
73, Cecil http://www.qsl.net/w5dxp

Current through coils
 

Ian White GM3SEK wrote:
I flatly do not accept your notion of a special kind of "standing wave
current" that has its own special kind of phase properties.

We already know that, Ian. Please drag out your dusty math book
and try to understand the difference between the standing wave
current function, func(kx)*func(wt), and the traveling wave
current function, func(kx +/- wt). They are obviously different.
Calling the standing wave current a "current" is something of
a misnomer since it doesn't exhibit the characteristics of a
normal current at all. What are the implications of a "fixed
phase" for a current, i.e. its phasor doesn't rotate?

Do you disagree with Gene's technically accurate posting on the
subject?
************************************************** ***************************
Gene Fuller, W4SZ wrote:
In a standing wave antenna problem, such as the one you describe, there is no
remaining phase information. Any specific phase characteristics of the traveling
waves died out when the startup transients died out.

Phase is gone. Kaput. Vanished. Cannot be recovered. Never to be seen again.

The only "phase" remaining is the cos (kz) term, which is really an amplitude
description, not a phase. The so-called "phase reversal" in longer antennas is
not really about phase either. It is merely a representation of the periodic
sign reversal seen in a cosine function.
************************************************** ****************************

The current that the loading coil experiences is plain old ordinary
alternating current flowing in the wire ...

False! Standing wave current is different from DC, AC, or RF
traveling waves. Please take time out to understand the
implications of a non-rotating phasor for a current. All other
AC currents have rotating phasors but the standing wave current
phasor doesn't rotate all up and down a 1/2WL thin-wire dipole.
That makes it extremely different from any other AC current.

Any special kind of current that requires electronic components to
behave in some different way from normal is simply not real.

The forward current and the reflected current are not special. The
superposed standing wave current doesn't behave as normal current at
all. It's phase doesn't change along the entire length of a 1/2WL thin-
wire dipole. I have said this a dozen times and it hasn't yet soaked
in yet so I will continue to repeat it. What does unchanging phase imply
about a standing wave current? All other AC currents change phase.

You have a fundamental misconception of what a standing wave of current
really is. You repeat all the words about "standing waves", "cos kz",
"scientific logic", "laws of physics" etc; but you don't actually let
any of it into your mind.

I am open-minded, Ian, and use the scientific method to correct my
mistakes and thus zero in on the technical facts. One of a guru's
presuppositions is that he already knows everything. I have no
such misconceptions about myself.

All the questions you ask other people are rooted in your own
misconceptions. In other words, the questions are rigged so that they
cannot be answered except by agreeing with you.

No, Ian, my questions are rigged so they cannot be answered except
by agreeing with the laws of physics and gurus cannot afford to show
their ignorance of the laws of physics. That leaves them between a
rock and a hard place as far as answering my questions are concerned.
That's the only reason for the "Silence of the Gurus".
--
73, Cecil http://www.qsl.net/w5dxp

Current through coils
 

On Wed, 22 Mar 2006 13:08:37 GMT, Cecil Moore
wrote:

False! Gene Fuller, Tom Donaly, and Roy Lewallen have all made
postings that support my side of the argument against yours.

I, on the other hand (barring these misappropriated citations), have
busted this thread four times.

It lingers on in soap opera format for amusement purposes only.

Current through coils
 

Richard Clark wrote:
I, on the other hand (barring these misappropriated citations), have
busted this thread four times.

In your mind, delusions of grandeur certainly seem to work. :-)
--
73, Cecil http://www.qsl.net/w5dxp

Current through coils
 

On Wed, 22 Mar 2006 16:23:42 GMT, Cecil Moore
wrote:
I, on the other hand (barring these misappropriated citations), have
busted this thread four times.
In your mind, delusions of grandeur certainly seem to work. :-)
Through logic, on paper, at the bench, by gum. It certainly shut you
up.

Current through coils
 

Cecil Moore wrote:
We already know that, Ian. Please drag out your dusty math book
and try to understand the difference between the standing wave
current function, func(kx)*func(wt), and the traveling wave
current function, func(kx +/- wt). They are obviously different.
Calling the standing wave current a "current" is something of
a misnomer since it doesn't exhibit the characteristics of a
normal current at all. What are the implications of a "fixed
phase" for a current, i.e. its phasor doesn't rotate?

This can be improved.

Current is charge movement. DC, traveling waves and standing waves
all are *exactly* charge moving past a given point, and nothing more.

A phasor is not a real thing, but a mathematical abstraction that
relates how the sinusoidal change in current magnitude and direction
relate to a reference periodic cycle in time. Since, in both standing
waves and traveling waves, current at a point, changes magnitude and
sign in exactly the same way (at a point, they are indistinguishable),
they can both be described with phasor notation.

The difference between a traveling wave and a standing wave is how the
phasor representing the current at one point differs from the phasor
representing the current at a neighboring point.

For traveling waves, the phasor of a neighboring point has the same
amplitude but a different phase shift (passes through zero at a
different time).

For standing waves, the phasor of a neighboring point has the same
phase shift, but a different amplitude, unless the neighboring point
is on the other side of a current node. Then it has the opposite phase.

But at any point along both standing waves and traveling waves, there
certainly is a phasor that represents the current at that point.

You need to get past this misconception that standing waves are not
current and are not describable by phasors. I think your concepts are
correct in lots of ways and recently improving, but this is a
recurring snag that keeps detouring your adversaries into straw men
that you offer them on a platter.

Current through coils
 

Richard Clark wrote:
On Wed, 22 Mar 2006 13:08:37 GMT, Cecil Moore
wrote:

False! Gene Fuller, Tom Donaly, and Roy Lewallen have all made
postings that support my side of the argument against yours.

There's very little about Cecil's theories that I agree with. He's made
many statements which are completely false as I've pointed out numerous
times, and his conclusions are largely based on misconceptions and
faulty understanding of basic principles.

Roy Lewallen, W7EL

Current through coils
 

Roy Lewallen wrote:
(snip)
I think the problem Cecil is having with it is that the currents on an
antenna behave in a manner that's similar to an open circuited
transmission line, which results in the phase angle of the total current
-- which can be represented as a phasor -- being the same at every point
along the line. The total current isn't current which has "stopped
flowing".

He is so close, but still has a couple misconceptions blocking him.

Current through coils
 

John Popelish wrote:
Since, in both standing
waves and traveling waves, current at a point, changes magnitude and
sign in exactly the same way (at a point, they are indistinguishable),
they can both be described with phasor notation.

Limiting oneself to a point measurement is handicapping onself. When
the equation for standing wave current is compared to the equation
for traveling wave current, the real differences are obvious.

For standing waves, the phasor of a neighboring point has the same phase
shift, ...

Exactly! Therefore, it cannot be used to measure the phase shift
through a coil or even through a wire.

But at any point along both standing waves and traveling waves, there
certainly is a phasor that represents the current at that point.

For the standing wave current it is a phasor that doesn't rotate
all up and down the wire. You have to admit, that's a weird phasor.
It's more akin to DC than anything else.

You need to get past this misconception that standing waves are not
current and are not describable by phasors.

Standing waves current is the superposition of two essentially equal
currents traveling in opposite directions. If it was equal DC
currents traveling in opposite directions, what would the net current
be?
--
73, Cecil http://www.qsl.net/w5dxp

Current through coils
 

Ian White GM3SEK wrote:

All the questions you ask other people are rooted in your own
misconceptions. In other words, the questions are rigged so that they
cannot be answered except by agreeing with you.


Cecil, W5DXP wrote:
No, Ian, my questions are rigged so they cannot be answered except
by agreeing with the laws of physics and gurus cannot afford to show
their ignorance of the laws of physics. That leaves them between a
rock and a hard place as far as answering my questions are concerned.
That's the only reason for the "Silence of the Gurus".
--


Esteemed gentlemen:

I am more of an engineer, inventor rather than scientist, analytic, cosine
kind of guy. But I will elevate myself on an occasion to find the root of
the problem and proof if needed. Let me try to put the things in
perspective, from real life facts, to this "scientwific" debate about the
"problem".

1. First I was smacked by the fact that on my 80m Hustler resonator, I
re-shrinked, (burned) the insulation on the coil from the bottom up, while
operating contest, mobile from Toronto, while spending few last days with my
dear mother. I was running about 600W to regular (200W) 80m coil with
heavier duty transmitting, during the contest, it was no surprise that it
melted the heat shrink tubing covering the turns.
Most people make occasional transmission and do not fry the coil even with
more that what it is rated for. On 40m and up I rewound other coils with
heavy wire or tubing and extended whips. I would not see the problem there.
I appeared to me strange that the bottom of the coil was fried. Normally I
would have expected either "uniform frying" , or perhaps more on the top due
to the raising, accumulating heat.
It kind of bothered me, because it was against the conventional "wisdom" or
what I knew.

2. When the topic came up, Barry, W9UCW, knew about the effect and done some
real life, real antennas, real RF ammeters measurements and found out that
indeed, the RF current at both ends of a typical loading coil (quarter wave
resonant, coil loaded vertical antenna) is different. He described it,
offered some photos and data about the measurements.
Please see http://www.k3bu.us/loadingcoils.htm
In his example he showed that 40m typical, loaded vertical, had about 40%
less current at the top than at the bottom. That made me happy, it made
sense and explained what was happening with my Hustler. So I got some
insight into the workings of the loaded, shortened radiator or element.
Reality agreed with engineering measurements, experiment, that anyone can
reproduce and verify.
The conclusion was:
"There IS a drop, difference in RF current across the antenna loading coil."
The significance (to me anyway): Efficiency of the radiator, antenna is
proportional to the area under the (cosine) curve of the current
distribution across the radiator. The loading coil, as it turned out, had
significant contribution to that current distribution that it got my
attention. Knowing the effect, we can play with different position of the
loading coil within the radiator and experiment with various ways of top
loading, to maximize the current flow within the desired portion of the
radiator, to maximize the area under the cosine current curve - to maximize
the efficiency under given restriction for the particular antenna design.
Here comes the compromise between loading inductance (coil, stub) vs.
capacitive hat (T, L, disk) loading.
So in the typical loaded (mobile or shortened) vertical we are trying to
maximize the efficiency and it is important to know what is the current
distribution across the radiator. If the coil has a drop in order of 40 -
60% as it appears to be, than that is significant to me to take it into the
account. Knowing how to apply this effect will allow me to optimize,
maximize the antenna performance.
So far with me? If not, ask the questions or tell me where I am wrong.

3. Then Tom, W8JI and his followers, with some "backing" from literature
(plenty are wrong), some experiments, modeling, came to "prove" that it
can't be so. His conclusion: "The current in the antenna loading coil is the
same at both ends". Then the "fight" and controversy started.
It appears to me that JI camp is coming from the theoretical end of it,
applying laws of physics and theories that do not apply to the case in
question.

4. Cecil, W5DXP came to the rescue by explaining and modeling the case and
supporting K3BU/W9UCW case and reality. We were happy to have that support,
shining more light on the scientific side of the effect and effort to
correlate the crude observations, real life measurements with theory,
modeling and analytical end of it.

5. Not so fast. JI camp vehemently defended their "equal current" case,
using examples, modeling, tailored to support their claims, for some reason
ignoring the reality, measurements, experiments done to set the coil in the
spot where current can be, and is the same (no argument with that).

6. Cecil, W5DXP started to dig deeper into the effect, showed that if we
model the coil as a loading stub, EZNEC shows the difference in the current.
When modeled as a solenoid, it also shows the difference. When the loading
is inserted as a simple L (zero physical size) inductance, then EZNEC
"proves" that current is the same. So for the same inductance, of different
physical model (same electrical) properties EZNEC "proves" that each camp is
"right". The only problem is, which case represents the reality and should
be taken seriously.
To prove the point further, Cecil showed that positioning the coil in
various position within the radiator, one can aggravate the difference in
current at the ends from one extreme of being equal, to the other extreme of
being max at one end and zero at the other, depending on the size of
inductor, position within the antenna and frequency applied. To me it makes
sense, explains the "workings" of the effect, puts some numbers on it and
shows how to model it, apply it and UNDERSTAND it. That's the way IT IS -
the reality. Anyone can verify it, do the experiment (otherwise, please
prove us wrong and where) and now - even model it in EZNEC when using proper
definition of the model coil (solenoid or loading stub of equivalent
inductance).

7. No, Cecil, didn't do the stupid mobile antenna trick with quarter wave
extension. He used it as an example to show how one can play with the model
to see the different situations and show that current can be from equal to
extreme (max to zero) across the loading coil. In the EZNEC you can vary the
position of the coil (solenoid or stub), length of the radiator and
frequency to see the current value and distribution across the
coil/radiator. Thanks to Cecil (and "solenoid" Roy), we have now improved
way of modeling the effect, understanding it and better way of applying to
antenna design. Thanks Cecil, you have golden patience, persistency and are
a great defender of the TRUTH!

8. But Noooo! W8JI camp and non-believers can not accept that (reality).
They cling to the "explanations" why it can't be so, because of "purple
electrons, phasor eating extremists" would not allow it to be so. They are
dancing around the facts and examples of why it is not so, not answering
latest W5DXP questions, but the main thing - not verifying the reality with
proper experiment or measurement (not important?). They are trying to prove
that reality isn't, Tesla and others are fools, because of what??? Pride?
Can't be wrong? Emperor has equal current clothes?

9. If anyone is trying to argue the case that (eventually) current is (or
close to) equal, by arguing that sticking the coil at the base or where
there is virtually no difference because of the position of the coil and
current distribution in the radiator, forget it. We are not arguing that
(and we agree with THAT special case). We are arguing with general
statement, as displayed on W8JI pages and argued by the "guru followers"
that the "RF current across the antenna loading coil IS (always) the same"
(or close, losses, bla, bla) in the TYPICAL loaded or mobile antenna. NOT in
the special case where it indeed can be. THAT WAS the subject of the
discussion and problem that started all of this. Not current in ANY coil, in
ANY circuit. We are not arguing minute diffrences due to radiation,
resistance, capacitance surface effect, etc., we are arguing the difference
of a 40 - 60 % of current drop across a typical loading coil in a typical
mobile or loaded antenna.

10. According W8JI camp, looking at the quarter wave loaded whip, the
current goes up the radiator according to cosine curve, then is the same
across the coil, then tapers to zero at the tip in the triangular shape
(should be the rest of the cosine curve, but close enough approximation). We
are talking about typical loaded resonant quarter wave ant, (not any coil in
any circuit).

11. According to K3BU camp, the same happens as above, except the current
across the coil drops at the top of the coil to typical 60 - 40 % (for 80 -
40m) and then tapers to zero at the tip. Again, (I hope no dispute over
this) efficiency of the antenna is proportional to the area under the
current distribution curve across the radiator with the loading coil. So
according to W8JI camp, the loaded radiator would have better efficiency
than it really has, by about 60 - 40 % of the above the coil current curve
area.

12. To me this is significant and worth exploring, because knowing the
effect will allow me to better design, model and optimize antenna systems
with loaded elements. The difference in the amount of current in the
remaining portion of the antenna is not negligible and the effect will
magnify itself when designing multielement loaded antennas. If the model
shows wrong amounts and distribution of the current, the results will be off
and real antenna will not perform as modeled. Those ARE the currents we
consider in modeling, show their distribution off and calculate the antenna
parameters with (right Roy?) So, to some the whole argument may be
insignificant, to me it is, it should be known, properly considered and
applied in the antenna modeling and design, otherwise it could cause
inaccuracies and wrong results.

13. So where are we now? We have the effect, we have the measurements, we
have explanation, we have the recipe how to model it properly, we have some
results. Others can duplicate and verify it. (And answer the frickin Cecil's
questions!!!!)
Then we have W8JI camp that insists that it ain't so, twisting and dancing
trying to "prove" that it just can't be so. Using "arguments" of their own,
often contradicting themselves (ooops) that it just couldn't be, because,
because, because....
Well, IT IS, if your egos like it or not. It is almost amusing to read the
thread and arguments trying to defy the reality by "scinetwific proof".
Cecil's arguments and question are selectively ignored and not argued, while
new twists and detours are brought in.

14. So if the W8JI camp can not swallow reality, so be it, eventually live
with giant egg on the face. I am extremely grateful to W9UCW, W5DXP and
others in "our" camp for their contribution to the discussion, explanations,
shedding their light and wisdom on the subject (and patience, and
persistence). I have learned more about the loaded antennas and will use it
especially in the design of receiving arrays for the new Tesla Radioclub
salt water marsh 175 acre antenna farm (www.TeslaRadio.org)

15. One more time, friendly advise to Tom, W8JI: If you strongly defend
posting the truth on Internet, live by it. It takes big guy to admit being
wrong, learn and give credit where it is due! Ridiculing someone being
wrong, especially when he is right is not in the spirit of ham radio and
decency. Playing guru, engineer and pontificating might go well on TV show
but in real life there are consequences. Arguing on a wrong side, then after
realizing being wrong, going QRT for a while and then emerging as a guru and
portraying the subject as own invention, without giving credit to "arguer"
smells with plagiarism. I am saying this here, because I was few times
publicly ridiculed by Tom while being right, as he later confirmed by
eventually propagating "my gospel" as his own. We should be engaging in
civil discussions and arguing about the topics, so we can all learn and be
better. If this whole exercise will contribute to that, then it was worth
it. If not, then keep on truckin'.

16. To the rest of the readers, I though that by now we all would be on the
same "camp reality", but looks like there is still a rocky road ahead. I
think we will get better results and go to radio heaven for sticking to the
"current in loading coils" truth. I promised comprehensive article on the
subject, but life keeps throwing more important problems in my path, but I
will try hard to do it soon. We shall summarize our camp's wisdom and hope
for convincing case for the unbelievers.

I tried to portray the picture of reality and significance of the subject in
hope of bringing the refusniks aboard. You all can be the judges of what
good it was.

We could look at some other "gospels" at Tom's web site, but that is another
story when subject comes up. (All in the name of dispelling the myths and
old waives tales as Tom likes to do.) I don't like to pick a fight, but I
don't stand by when there is a significant myth or wrongo being propagated,
I will defend the truth with my last breath (if it is worth it :-)

I think 'nuf said, we all did our best to conway the reality, the readers
can draw their own conclusions and if important, verify this and that to see
who is RIGHT and if they can benefit from the findings. Good luck and I rest
my "piece of coil".

73 Yuri Blanarovich, www.K3BU.us