Current across the antenna loading coil - from scratch
 

W8JI Wrote:
The current you measure with a clamp on meter or any other reliable
current meter that does not greatly perturb the circuit is the current
that causes radiation, it is the current that causes heating, and it is
the current we would use to calculate power.

Cecil Moore wrote:
There's absolutely no argument about that. Both forward waves and
reflected waves radiate so standing waves obviously radiate. Both
forward waves and reflected waves cause I^2*R losses. Stating such
obvious technical facts is a diversion and a waste of words.

Cecil,

Please humor all of us.

You now seem to agree the current we measure, which is the current that
causes radiation, causes heating, and that we can use to determine
phase or power levels is what Roy, I, and a dozen others have been
saying.

So what exactly is the importance of this current YOU are talking
about? Since it does not cause radiation, does not cause heat, and does
not determine phase....exactly what does it do?

73 Tom

Current across the antenna loading coil - from scratch
 

Cecil Moore wrote:

Please explain the results posted at: http://www.qsl.net/w5dxp/travstnd.GIF

Cecil,

You may believe it is obvious, but it is not quite clear what you are
trying to show in that figure. On the left side, traveling wave, it
appears that "magnitude" means Io. On the right side, standing wave, it
appears that "magnitude" means Io cos(kx).

The gist of your position seems to be that somehow the traveling wave is
more powerful, or at least different, since the area under the current
magnitude curve is larger. In reality, however, it is necessary to pick
a single time at which to compare the two cases. It is of little value
to look at some sort of overall envelope for the traveling wave. The
correct magnitude of the traveling wave never has the shape of the
overall envelope. Pick a single time, say when wt is equal to zero or
equal to pi. Then compare the curves. In fact, if you pick any single
time for the left side the resulting curve shape will look a lot like
the right side.

73,
Gene
W4SZ

Current across the antenna loading coil - from scratch
 

Current across the antenna loading coil - from scratch
 

wrote:
So what exactly is the importance of this current YOU are talking
about?

All the diversionary BS trimmed from your posting. Bottom line,
the equation for standing wave current is:

I(x,t) = Io*cos(kx)*cos(wt)

The equation for traveling wave current is:

I(x,t) = Io*cos(ks+wt)

Since you obviously don't comprehend the difference, please
dust off your old math book and take a look.

In case you need a graphics reference for those two equations,
you can find it at: http://www.qsl.net/w5dxp/travstnd.GIF

You will find the two above currents are virtually opposites
of each other.

In particular, standing wave current phase CANNOT be used to
determine the phase shift through a wire or through a coil
because its phase never changes in a 1/4WL monopole.

I can hardly say it better than Gene Fuller who said:
Regarding the cos(kz)*cos(wt) term in a standing wave:

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.

Please tell us what it is about Gene's posting that you don't
understand.
--
73, Cecil http://www.qsl.net/w5dxp

Current across the antenna loading coil - from scratch
 

Gene Fuller wrote:
You may believe it is obvious, but it is not quite clear what you are
trying to show in that figure. On the left side, traveling wave, it
appears that "magnitude" means Io. On the right side, standing wave, it
appears that "magnitude" means Io cos(kx).

No, both plots are for I(x,t). The magnitude of the traveling wave
current is constant while the phase changes with 'x'. The phase of
the standing wave current is constant while the magnitude changes
with 'x'. They are virtually opposites of each other.

It is of little value
to look at some sort of overall envelope for the traveling wave.

Both currents are phasor RMS values along with their phases.

I am reporting *exactly* what EZNEC reports. If you don't like
that, talk W7EL into reporting something different.
--
73, Cecil http://www.qsl.net/w5dxp

Current across the antenna loading coil - from scratch
 

Cecil Moore wrote:
wrote:

So what exactly is the importance of this current YOU are talking
about?


All the diversionary BS trimmed from your posting. Bottom line,
the equation for standing wave current is:

I(x,t) = Io*cos(kx)*cos(wt)

The equation for traveling wave current is:

I(x,t) = Io*cos(ks+wt)

Since you obviously don't comprehend the difference, please
dust off your old math book and take a look.

In case you need a graphics reference for those two equations,
you can find it at: http://www.qsl.net/w5dxp/travstnd.GIF

You will find the two above currents are virtually opposites
of each other.

In particular, standing wave current phase CANNOT be used to
determine the phase shift through a wire or through a coil
because its phase never changes in a 1/4WL monopole.

I can hardly say it better than Gene Fuller who said:
Regarding the cos(kz)*cos(wt) term in a standing wave:

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.


Please tell us what it is about Gene's posting that you don't
understand.

Cec;

Please answer the man's question. Don't prevaricate. Don't deviate.
Answer the damn question.

Except for this particular subject I have great admiration for you
knowledge and have learned from you. This subject seems to be your
bugaboo. I have completely lost track of what the object of the exercise is.

Dave N

Dave N

Current across the antenna loading coil - from scratch
 

Cecil Moore wrote:
Gene Fuller wrote:

You may believe it is obvious, but it is not quite clear what you are
trying to show in that figure. On the left side, traveling wave, it
appears that "magnitude" means Io. On the right side, standing wave,
it appears that "magnitude" means Io cos(kx).


No, both plots are for I(x,t). The magnitude of the traveling wave
current is constant while the phase changes with 'x'. The phase of
the standing wave current is constant while the magnitude changes
with 'x'. They are virtually opposites of each other.

It is of little value to look at some sort of overall envelope for the
traveling wave.


Both currents are phasor RMS values along with their phases.

I am reporting *exactly* what EZNEC reports. If you don't like
that, talk W7EL into reporting something different.

Cecil,

Perhaps I was not clear. I understand the plots, and I have no question
that they show what EZNEC provides.

My question is why you feel there is anything of significance or
anything for the "gurus" to ponder.

As I explained, the curves are mostly a comparison of apples to oranges.
One (standing wave) shows the peak current at when the cos(wt) factor is
at a maximum. The other (traveling wave) shows the envelope of all the
current shapes over time. They are really two different entities, and
they have virtually no application to the topic featured in the past
17,000 messages.

What you call the "magnitude" of the traveling wave never actually
represents the current over the length of wire at any point in time.

73,
Gene
W4SZ

Current across the antenna loading coil - from scratch
 

Roy Lewallen wrote:

So for starters, why don't you explain how your theory fits with the
existing model results? Why is the current drop the same with an antenna
and for a lumped circuit? Why does removing ground make the current drop
go away? Why is there no significant phase shift in current from bottom
to top? Conventional theory can explain this. Can yours?

As for your promise to write the article, I have to point out that
you've made this promise before without delivering. So I'm not exactly
holding my breath waiting for it. I'm sure it'll make interesting
reading, though, and it's a revolutionary enough theory that the IEEE,
or at the very least QEX, should be happy to publish it when it's
finally complete.

Roy Lewallen, W7EL

Roy, I will make you a bet. Lunch, if you might be at Central States
this year.

Not Gonna Happen.

They are not interested in reality. They are not interested in
engineering. They do not want to understand physics, or they are not
capable. It matters not.

I have been watching, and reading, and would like to see you, and the
others, stop beating a very dead horse. Cecil and Yuri will never get it.

Tom
K0TAR

Current across the antenna loading coil - from scratch
 

Gene Fuller wrote:
You may believe it is obvious, but it is not quite clear what you are
trying to show in that figure.

Gene, I previously responded in words that I thought you would
understand, based on your previous understanding. It occurred
to me during my walk that not every reader is an engineer, not
every engineer is a EE, and not every EE also has a math degree.

Here it is in easier to understand terms. Given the 1/4WL conductor
and the web page at:

http://www.qsl.net/w5dxp/travstnd.GIF

The way to measure phase shift through a wire carrying the
traveling wave current is to put a current probe at location
A and location B, and measure the phase shift between those
two equal magnitude sine waves. If a coil exists in the circuit,
that would also be the way to get a rough measure of the phase
shift across the coil.

Example: The phase shift from 30% to 60% in the traveling wave
antenna is taken from the tabular data as 54.2-27.6 = 26.6 degrees.

The phase information is in the *phase* in a traveling wave.

For the standing wave current, the situation is completely
different. The phase measured between any two current probes
will always be zero. The phase of a standing wave current is
useless for measuring phase shift. The way to extract the
phase information is to measure the *amplitude* at two points
and then calculate the phase shift by taking the arc-cos of
the normalized amplitude.

Example: The phase shift from 30% to 60% in the standing wave
antenna is arc-cos(0.8843) - arc-cos(0.5840) = 26.5 degrees.

The phase information is in the *amplitude* in a standing wave.

Thus in both antennas, the phase shift in 30 percent of the
wire is about 27 degrees. (90*.3 = 27) If we had a coil installed
in that 30 degrees of the antenna instead of a wire, the same
concepts would apply.
--
73, Cecil http://www.qsl.net/w5dxp

Current across the antenna loading coil - from scratch
 

David G. Nagel wrote:
Please answer the man's question. Don't prevaricate. Don't deviate.
Answer the damn question.

Maybe one of my other postings answers the question for you.
I'm not prevaricating or deviating. I'm answering the questions
to the best of my ability. Gene's posting is one of the best
answers to Tom's questions that I have seen. Gene says there is
ZERO information in standing wave phase. I agree with Gene.

Except for this particular subject I have great admiration for you
knowledge and have learned from you. This subject seems to be your
bugaboo. I have completely lost track of what the object of the exercise
is.

The object of the exercise is to prove that standing wave current
phase cannot be used to measure the phase through a wire or coil
or anything else. The phase of a standing wave is already known
and is unchanging. The only phase information in a standing wave
current is contained in the amplitude.
--
73, Cecil http://www.qsl.net/w5dxp

Current across the antenna loading coil - from scratch
 

Roy Lewallen wrote:

So for starters, why don't you explain how your theory fits with the
existing model results? Why is the current drop the same with an antenna
and for a lumped circuit? Why does removing ground make the current drop
go away? Why is there no significant phase shift in current from bottom
to top? Conventional theory can explain this. Can yours?

As for your promise to write the article, I have to point out that
you've made this promise before without delivering. So I'm not exactly
holding my breath waiting for it. I'm sure it'll make interesting
reading, though, and it's a revolutionary enough theory that the IEEE,
or at the very least QEX, should be happy to publish it when it's
finally complete.

Roy Lewallen, W7EL

Sorry, I forgot to mention that they also don't appear to understand
math, or the fact that "complex numbers" are quite simple if you went to
engineering school and own an HP15 calculator. Mine still works fine.

If you had trouble with the previous statement, Cecil and Yuri, I meant
that your "phasor" math is trivial. At best 2nd year engineering. And
yes, we do understand it. A lot more than you do apparently.

tom
K0TAR

Current across the antenna loading coil - from scratch
 

Gene Fuller wrote:
My question is why you feel there is anything of significance or
anything for the "gurus" to ponder.

Hopefully, I answered that question in my other posting. If one
wants to measure phase shift using a traveling wave current, one
measures the phase shift between two points.

If one wants to measure the phase shift using a standing wave
current, one measures the amplitudes at two points and subtracts
the arc-cosines of the normalized amplitude values.

You said essentially the same thing in your earlier posting -
that there is no phase information in the standing wave current
phase and all the phase information is in the amplitude values.
--
73, Cecil http://www.qsl.net/w5dxp

Current across the antenna loading coil - from scratch
 

Tom Ring wrote:
They are not interested in reality. They are not interested in
engineering. They do not want to understand physics, or they are not
capable. It matters not.

You are, of course, talking about QEX.

Tom, maybe you can explain how to use standing wave current phase
to measure the phase shift through a wire? If you can, I would
really appreciate it.
--
73, Cecil http://www.qsl.net/w5dxp

Current across the antenna loading coil - from scratch
 

Tom Ring wrote:
If you had trouble with the previous statement, Cecil and Yuri, I meant
that your "phasor" math is trivial. At best 2nd year engineering. And
yes, we do understand it. A lot more than you do apparently.

Well then, please prove W8JI's assertion that "current is current",
i.e. that cos(kx+wt) = cos(kx)*cos(wt) at every point up and down
the wire. That should be "trivial" for you.

If you cannot prove that, please explain to us how and why
standing wave current is different from traveling wave current.
(That's what I have been doing.)

During your explanation of the difference, you will realize why
W7EL's standing wave phase measurements are meaningless - that
there is no phase information in standing wave current phase.
As Gene said, all the phase information is in the standing wave
current *amplitude*, not in the phase.
--
73, Cecil http://www.qsl.net/w5dxp

Current across the antenna loading coil - from scratch
 

"David G. Nagel" wrote
I have completely lost track of what the object of the exercise is.

=======================================

I gave up trying just after the thread began.

What put me off was "current across the coil" when everybody knows it
should be "current through the coil".

It is VOLTS which appear ACROSS coils.
----
Reg.

Current across the antenna loading coil - from scratch
 

Tom Ring wrote:

Roy, I will make you a bet. Lunch, if you might be at Central States
this year.

Are you kidding? With odds about the same as winning the lottery?

Not Gonna Happen.

They are not interested in reality. They are not interested in
engineering. They do not want to understand physics, or they are not
capable. It matters not.

I have been watching, and reading, and would like to see you, and the
others, stop beating a very dead horse. Cecil and Yuri will never get it.

Oh, I know all that.

I'm not posting in an attempt to educate Cecil and Yuri or to change
their minds -- it became evident years ago that's a waste of time. The
only reason I bother is in the hopes that it'll play some part in
preventing some of the lurkers from getting sucked in by the flurry of
informed-sounding but demonstrably wrong arguments which continue to
come from those folks. It's hard to say if it's having any effect, but I
think it's important to present a point of view supported by established
theory, modeling, and measurement results which are all in agreement
rather than letting the pseudo-science stand alone as apparent fact.

Roy Lewallen, W7EL

Current across the antenna loading coil - from scratch
 

Reg Edwards wrote:
"David G. Nagel" wrote

I have completely lost track of what the object of the exercise is.


=======================================

I gave up trying just after the thread began.

What put me off was "current across the coil" when everybody knows it
should be "current through the coil".

It is VOLTS which appear ACROSS coils.
----
Reg.


evidently Cecil doesn't.

Dave

Current across the antenna loading coil - from scratch
 

Cecil,

I thought you denounced and denied this "concept" earlier today.

73,
Gene
W4SZ


Cecil Moore wrote:
If we had a coil installed
in that 30 degrees of the antenna instead of a wire, the same
concepts would apply.

Current across the antenna loading coil - from scratch
 

Roy Lewallen wrote:
The
only reason I bother is in the hopes that it'll play some part in
preventing some of the lurkers from getting sucked in by the flurry of
informed-sounding but demonstrably wrong arguments which continue to
come from those folks.

Roy, it is demonstrably wrong to try to use standing wave current
phase to measure the delay through a coil. Anyone, including you,
who says it is a valid procedure is either ignorant or trying to
hoodwink the lurkers.
--
73, Cecil http://www.qsl.net/w5dxp

Current across the antenna loading coil - from scratch
 

Gene Fuller wrote:
I thought you denounced and denied this "concept" earlier today.

Guess you misunderstood. A coil can replace 30 degrees of
an antenna but it won't use the same amount of wire as
30 degrees of wire. What I said is that an inductor is
more efficient than linear loading.
--
73, Cecil http://www.qsl.net/w5dxp

Current across the antenna loading coil - from scratch
 

David G. Nagel wrote:
evidently Cecil doesn't.

It wasn't me who started this thread.

If we have one amp of DC current flowing one direction and
one amp of DC current flowing the other direction, which
direction is the sum of those currents flowing?

If we have one amp of forward RF current and one amp of
reflected RF current, which direction is the sum of those
currents flowing?
--
73, Cecil http://www.qsl.net/w5dxp

Current across the antenna loading coil - from scratch
 

Cecil Moore wrote:
wrote:

So what exactly is the importance of this current YOU are talking
about?


All the diversionary BS trimmed from your posting. Bottom line,
the equation for standing wave current is:

I(x,t) = Io*cos(kx)*cos(wt)

The equation for traveling wave current is:

I(x,t) = Io*cos(ks+wt)

Since you obviously don't comprehend the difference, please
dust off your old math book and take a look.

In case you need a graphics reference for those two equations,
you can find it at: http://www.qsl.net/w5dxp/travstnd.GIF

You will find the two above currents are virtually opposites
of each other.

In particular, standing wave current phase CANNOT be used to
determine the phase shift through a wire or through a coil
because its phase never changes in a 1/4WL monopole.

I can hardly say it better than Gene Fuller who said:
Regarding the cos(kz)*cos(wt) term in a standing wave:

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.


Please tell us what it is about Gene's posting that you don't
understand.

You know, Cecil, a pulse train also satisfies the wave equation.
Why are you married to sinusoidal waves? Haven't you ever seen
ghosts on a tv picture? What do those Ghosts represent?
73,
Tom Donaly, KA6RUH

Current across the antenna loading coil - from scratch
 

Reg Edwards wrote:

"David G. Nagel" wrote

I have completely lost track of what the object of the exercise is.


=======================================

I gave up trying just after the thread began.

What put me off was "current across the coil" when everybody knows it
should be "current through the coil".

It is VOLTS which appear ACROSS coils.
----
Reg.



They also like to talk about "current drops" when they mean the
difference in current amplitude at two different points.
73,
Tom Donaly, KA6RUH

Current across the antenna loading coil - from scratch
 

Cecil Moore wrote:
David G. Nagel wrote:

evidently Cecil doesn't.


It wasn't me who started this thread.

If we have one amp of DC current flowing one direction and
one amp of DC current flowing the other direction, which
direction is the sum of those currents flowing?

If we have one amp of forward RF current and one amp of
reflected RF current, which direction is the sum of those
currents flowing?

I was taught that under these circumstances DC and RF work differently.
Yes your DC net current is zero. Your new RF current is one amp in each
direction.

Dave WD9BDZ

Current across the antenna loading coil - from scratch
 

"Cecil Moore" wrote in message
m...
You said essentially the same thing in your earlier posting -
that there is no phase information in the standing wave current
phase and all the phase information is in the amplitude values.

thats the basic problem in this whole discussion. you are all talking about
the same thing, just using different notation and incomplete statements so
that none of you understands exactly what the others are trying to talk
about... when really you are all saying the same thing. its kind of like
after i graduated from college with an ee degree and my sister graduated
from an air force basic electronics course, she tried to ask me something
about currents in a transistor and i saw it all backwards... well of course
she was talking electron flow and i was talking hole flow. we both got the
same result but the notation was all different.

so, now i will raise my voice...

STOP THIS PETTY BICKERING AND GET OUT THERE AND USE AN ANTENNA INSTEAD OF
ARGUING ABOUT WHY THEY DON"T WORK THEY WAY YOU THINK THEY SHOULD!

Current across the antenna loading coil - from scratch
 

Tom Donaly wrote:
You know, Cecil, a pulse train also satisfies the wave equation.
Why are you married to sinusoidal waves? Haven't you ever seen
ghosts on a tv picture? What do those Ghosts represent?

If one doesn't understand sinusoidal waves, one doesn't have
a ghost of a chance of understanding a pulse train. Trying
to introduce a pulse train before understanding sinusoidal
values is just muddying the waters.

In a closed system, such as a source, transmission line, and
receiver, ghosting represents reflected waves.
--
73, Cecil http://www.qsl.net/w5dxp

Current across the antenna loading coil - from scratch
 

Tom Donaly wrote:
They also like to talk about "current drops" when they mean the
difference in current amplitude at two different points.

For an EM wave in a lossy environment, the attenuation factor
applies equally to the E-field and H-field, i.e. equally to
voltage and current. Both "drop" at the same rate.

The transmission line voltage equation contains that attenuation
factor and the current equation is simply the voltage equation
divided by the characteristic impedance.

In a lossy transmission line, the H-field and E-field "drop"
at the same rate since their ratio is fixed by the
characteristic impedance.

One more proof that EM waves are NOT lumped circuit voltages
and currents.
--
73, Cecil http://www.qsl.net/w5dxp

Current across the antenna loading coil - from scratch
 

David G. Nagel wrote:

Cecil Moore wrote:
If we have one amp of forward RF current and one amp of
reflected RF current, which direction is the sum of those
currents flowing?

I was taught that under these circumstances DC and RF work differently.
Yes your DC net current is zero. Your new RF current is one amp in each
direction.

Yes, that is true, but EZNEC doesn't report the two separate
currents. EZNEC reports the phasor sum of those two currents
in magnitude and phase. So the question still remains: In
which direction is the total current reported by EZNEC
flowing? What does the unchanging phase really mean?

EZNEC says that, referenced to the source phase, the phase
of the phasor sum of the forward and reflected currents is
UNCHANGING. It makes no sense to pick a direction of flow
for the sum of two equal currents flowing in opposite
directions.

Standing wave current doesn't flow in the commonly accepted
meaning of "flow". Standing wave current just stands there.

I received the following email from a physics professor:

"As for the standing waves, they really aren't independent
creatures. They're an artifact - a construct which happens
to look like the superposition of fields which surround the
antenna. But the fields which superpose look like the traveling
waves. The traveling waves really tell the story."
--
73, Cecil http://www.qsl.net/w5dxp

Current across the antenna loading coil - from scratch
 

Dave wrote:
... when really you are all saying the same thing.

Unfortunately, we are not all saying the same thing.
W7EL and W8JI are saying that using standing wave
current phase to make a phase shift measurement is
a valid approach. They keep reporting their results of
using such an approach as if it were a valid thing to
do. When those useless phase measurements are discarded,
the technical picture becomes a lot clearer.

I, and others, are saying that using a signal with
unchanging phase will not and cannot tell one anything
about any phase shift. There is no phase information
contained in the standing wave phase. All of the phase
information is contained in the standing wave magnitude.

I'm building a web page about this subject. The initial
graphic is at: http://www.qsl.net/w5dxp/travstnd.GIF

Note that for a standing wave current, the only thing
changing with length is magnitude. The flat phase line
of the standing wave current is completely useless for
making phase measurements.
--
73, Cecil http://www.qsl.net/w5dxp

Current across the antenna loading coil - from scratch
 

Dave wrote:
thats the basic problem in this whole discussion. you are all talking about
the same thing, just using different notation and incomplete statements so
that none of you understands exactly what the others are trying to talk
about... when really you are all saying the same thing. its kind of like
after i graduated from college with an ee degree and my sister graduated
from an air force basic electronics course, she tried to ask me something
about currents in a transistor and i saw it all backwards... well of course
she was talking electron flow and i was talking hole flow. we both got the
same result but the notation was all different.

That's not true at all Dave. Most of us know that current is current.
It really only flows one direction at any instant of time. We can
indeed consider systems as having current that flows two directions at
one instant of time, but the results of that better agree with the
actual real current that flows only in one direction at any instant of
time or they are wrong.

Also, behavior of basic components cannot change. A two terminal device
like a loading coil cannot have differences in the current flowing
through it at each terminal without a third path. (I assume we all
know current is not an across vector and it does not "drop", the person
who started this thread just used poor wording.)

I think the basic problem is Cecil wants to used some definition of
current that does not allow models to be freely exchanged and does not
produce results that match real world systems. It always has to match.
We can't have different results unless someone has an error.

The only reason I'm skimming the posts here and making the occasional
comment is I hate to see people trying to understand how this stuff
works be confused. The real fuss is a couple people seem to think
standing waves or "missing antenna length" are the root cause of
current being different in the two terminal component called a loading
coil.

It really isn't an argument or debate as much as trying to help lurkers
understand how the system really works, and not let them fall into the
trap that the loading coil behavior is any different than any other
coil, the only possible reason for differences in current at each
terminal is stray capacitance allowing displacement currents to the
outside world, and that any phase differences in current at each coil
terminal are also tied to capacitance from the coil to the world around
the coil.

It's not correct to assume people are talking about the same result
different ways, because both Cecil and Yuri have huge flaws in their
conclusions. They both seem to want the inductor to behave in some very
unique way just because it is an antenna, and the reults they seem to
claim do not match actual measurements. Cecil dismisses real
measurements with frantic arm waving about reflected and forward
current and no one being able to measure current and phase because of
standing waves, and while I think Yuri would accept measurements he
won't accept them when made by others and won't make them himself.

This has gone on for perhaps three years now. It is really up to Cecil
and Yuri to let it go, since they are the ones who seem to disagree
with measurements and accepted theory.

73 Tom

Current across the antenna loading coil - from scratch
 

Dave wrote:
thats the basic problem in this whole discussion. you are all talking
about
the same thing, just using different notation and incomplete statements
so
that none of you understands exactly what the others are trying to talk
about... when really you are all saying the same thing. its kind of like
after i graduated from college with an ee degree and my sister graduated
from an air force basic electronics course, she tried to ask me something
about currents in a transistor and i saw it all backwards... well of
course
she was talking electron flow and i was talking hole flow. we both got
the
same result but the notation was all different.

That's not true at all Dave. Most of us know that current is current.
It really only flows one direction at any instant of time. We can
indeed consider systems as having current that flows two directions at
one instant of time, but the results of that better agree with the
actual real current that flows only in one direction at any instant of
time or they are wrong.

Also, behavior of basic components cannot change. A two terminal device
like a loading coil cannot have differences in the current flowing
through it at each terminal without a third path. (I assume we all
know current is not an across vector and it does not "drop", the person
who started this thread just used poor wording.)

ARGH! maybe it really is more basic than different notations and
terminology. when working with antennas and 'component's that are a
significant fraction of a wavelength in size you must take into account the
'third path'... the 'third path' consists of the distributed capacitance and
resistance that CAN be modeled with lumped components if you want to go
through all the approximations and extra calculations that are required. if
you are ignoring that 'path' when talking about relatively large loading
coils then you will be wrong, how wrong depends on how large of course.

i haven't been following all the different threads and junk in here, but if
you are trying to analyze a significant sized loading coil without taking
into account all the paths then you are going to likely be less accurate
than cecil using a more complete distributed model. OBVIOUSLY if you are
using a strict lumped model the current can't be different from one end to
the other. And just as obviously if you make a really large loading coil,
like a full '1/2 wave' slinky dipole, the current at the feedpoint end will
be MUCH different than at the open end. You can both get the same results,
but to do it with lumped elements requires the same calculations that are
done by finite element simulations that try to do enough small lumped
elements as possible to approximate the distributed equations that would
give nice smooth results. Unfortunately cecil does not do a good job in
relating the distributed model, and his constant references to 'optics' and
the use of terms related to that field do nothing but confuse many of the
people in here to think that he is in a different world. admit it cecil,
while you may be correct, using a different set of terminology than most of
the people in here has done nothing but add to the confusion factor in many
of this long drawn out threads.

I still think that if each of you explained the WHOLE problem in your own
terminology, INCLUDING all the assumptions that are required for the models
you are using, that you would find that each of you is correct. but because
you are starting from different sets of assumptions you will never find a
common ground.

enough of this, back to assembling my new linear loaded 40m beam... why
don't you go analyze that loading system for a while.

Current across the antenna loading coil - from scratch
 

wrote:

I had this example at the bottom of my posting but you seem
to ignore such. So I am moving it to the top of the posting.
If you ignore it now, at least everyone will know you couldn't
possibly have missed it.

You are in a room with a 50 ohm transmission line routed
through a hole in one side of the room, across the room,
and through a hole in the other side of the room. You don't
know which is the source end of the line. A directional
wattmeter reads 200 watts forward power and 200 watts
reflected power but you don't know which direction is
forward. Here's a diagram:

200W-- 2 amps--
hole-------------------50 ohm coax-------------------hole
--200W --2 amps

Which direction is the standing wave current flowing?

If you knew forward current was moving left to right which
direction would the standing wave current be flowing?

That's not true at all Dave. Most of us know that current is current.

Too bad EZNEC disagrees with you as seen in the graphic at:

http://www.qsl.net/w5dxp/travstnd.GIF

The traveling wave current is virtually the opposite of the
standing wave current as can be seen by their different
equations. There is no phase information in the standing
wave current phase. Yet that is exactly the phase W7EL
used to try to measure the delay/phase shift through a
coil.

DC current is different from AC current. That's why the
DC or AC designations are necessary. RF forward current
is different from RF standing wave current. That's why
the different designations are necessary.

It really only flows one direction at any instant of time.

Or not at all at a standing wave current node.
Too bad we are talking RMS values here which is what EZNEC
reports. I'll ask the question of you: If one amp of RF
current is flowing in one direction and one amp of RF
current is flowing in the opposite direction, which direction
does the phasor sum of those two currents flow?

We can
indeed consider systems as having current that flows two directions at
one instant of time, but the results of that better agree with the
actual real current that flows only in one direction at any instant of
time or they are wrong.

The phase of standing wave current is unchanging. It doesn't "flow"
in the commonly accepted sense of the word. As Hecht says in "Optics":

"This is the equation for a STANDING or STATIONARY WAVE, as opposed
to a traveling wave. Its profile does not move through space; it is
clearly not of the form Func(x +/- vt)."

[Standing wave phase] "doesn't rotate at all, and the resultant
wave it represents doesn't progress through space - its a standing
wave."

If standing wave light doesn't move through space, then standing
wave RF also doesn't move through a wire.

(I assume we all
know current ... does not "drop", ...)

EM current does indeed drop exactly like EM voltage drops both
according to the attenuation factor. Just one more proof that
EM waves are not lumped circuit currents. The only difference
in the equation for transmission line voltage and current is
the voltage gets divided by the characteristic impedance which
is usually a resistive constant.

I think the basic problem is Cecil wants to used some definition of
current that does not allow models to be freely exchanged and does not
produce results that match real world systems. It always has to match.
We can't have different results unless someone has an error.

Exactly correct and the reason for the different results is your
error. In any conflict between the distributed network model and
the lumped circuit model, the distributed network model wins
every time since it is a superset of the lumped circuit model.

This has gone on for perhaps three years now. It is really up to Cecil
and Yuri to let it go, since they are the ones who seem to disagree
with measurements and accepted theory.

On the contrary, it is up to you and others to correct your
misconceptions about standing wave current. Your "accepted
theory" has holes in it that I could drive my GMC pickup
through.
--
73, Cecil http://www.qsl.net/w5dxp

Current across the antenna loading coil - from scratch
 

Cecil Moore wrote:
Gene Fuller wrote:

I thought you denounced and denied this "concept" earlier today.


Guess you misunderstood. A coil can replace 30 degrees of
an antenna but it won't use the same amount of wire as
30 degrees of wire. What I said is that an inductor is
more efficient than linear loading.

Cecil,

I am feeling dizzy. I am quite comfortable with my understanding of the
entire problem, but I am seriously confused about your position. Nobody
has ever talked about efficiency or the length of wire needed. The issue
has always been replacing "degrees of antenna". I have captured a few
excerpts from April 7.

73,
Gene
W4SZ


Excerpt follow:

9:03 am -- From Cecil

K7ITM wrote:

Another 'speriment occured to me, for those who think the coil current
MUST be different at the two ends by the amount corresponding to the
antenna section it replaces:


To the best of my knowledge, nobody believes that. The coil
is much more efficient at the loading function than is the
straight wire from which it is made. That's why inductive
loading is more efficient than fractal antennas or other
types of linear loading.
--
73, Cecil http://www.qsl.net/w5dxp


9:24 am -- From Yuri

[excerpt]

Now you move that coil say half way up the must, to higher impedance
point at the antenna, and that coil now, in order to maintain the
"match" has to have higher impedance, more turns and will exhibit MORE
current drop across it, while replacing THE SAME NUMBER OF "missing"
DEGREES AT THE RADIATOR.
Assuming that our goal is to stay with the same physical length of the
whip (which we do) and maintaining 90 degrees of resonant radiator. So
the radiator stays 50 degrees ()+50, 10+40, 20+30, 30+20, 40 + 10) long
and coil replaces the same "missing" 40 degrees.

[emphasis was in the original message]


9:44 am -- From Cecil

Roy Lewallen wrote:

Of course loading coils can be expressed in electrical degrees. But
extrapolating this to mean that a loading coil has the same properties
as an antenna with the same number of "degrees" has no justification.

I haven't heard anybody make that assertion in years. Coils
occupy whatever number of degrees that they occupy.


8:49 pm -- From Cecil

[excerpt]

Example: The phase shift from 30% to 60% in the traveling wave
antenna is taken from the tabular data as 54.2-27.6 = 26.6 degrees.

The phase information is in the *phase* in a traveling wave.

For the standing wave current, the situation is completely
different. The phase measured between any two current probes
will always be zero. The phase of a standing wave current is
useless for measuring phase shift. The way to extract the
phase information is to measure the *amplitude* at two points
and then calculate the phase shift by taking the arc-cos of
the normalized amplitude.

Example: The phase shift from 30% to 60% in the standing wave
antenna is arc-cos(0.8843) - arc-cos(0.5840) = 26.5 degrees.

The phase information is in the *amplitude* in a standing wave.

Thus in both antennas, the phase shift in 30 percent of the
wire is about 27 degrees. (90*.3 = 27) If we had a coil installed
in that 30 degrees of the antenna instead of a wire, the same
concepts would apply.

Current across the antenna loading coil - from scratch
 

Dave wrote:
admit it cecil,
while you may be correct, using a different set of terminology than most of
the people in here has done nothing but add to the confusion factor in many
of this long drawn out threads.

I have a limited technical library. I wish my RF references spelled out
everything as well as "Optics", by Hecht, but mine don't. Light and RF
are the same kind of EM waves, just at different frequencies. Hecht's
material is certainly relevant to RF waves. And I make every effort to
translate the technical jargon from one field to the other as best I
know how.

Hecht presents the best treatment of superposition, interference,
and standing waves that I have ever seen. I wish I had an RF
reference book as well written as "Optics".
--
73, Cecil http://www.qsl.net/w5dxp

Current across the antenna loading coil - from scratch
 

Gene Fuller wrote:
I am feeling dizzy. I am quite comfortable with my understanding of the
entire problem, but I am seriously confused about your position. Nobody
has ever talked about efficiency or the length of wire needed. The issue
has always been replacing "degrees of antenna". I have captured a few
excerpts from April 7.

What you quoted from me is my reporting of what EZNEC says about
standing wave current Vs traveling wave current at:

http://www.qsl.net/w5dxp/travstnd.GIG

The 'x' axis for both conditions is just a piece of 1/4WL wire.
One can calculate the phase shift in any section of wire in two
ways:

1. For traveling waves, the phase shift is given by the graph
of the phase (red line). The magnitude (blue line) contains
no phase information.

2. For standing waves, the phase shift is given by taking the
arc-cosine of the magnitude (blue line). The phase (red line)
contains no phase information.

Before we talk about replacing a piece of wire with a coil,
do you understand the above graphic and concepts? You seemed
to understand when you posted:

Regarding the cos(kz)*cos(wt) term in a standing wave:

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.
--
73, Cecil http://www.qsl.net/w5dxp

Current across the antenna loading coil - from scratch
 

Cecil Moore wrote:
(snip)
You are in a room with a 50 ohm transmission line routed
through a hole in one side of the room, across the room,
and through a hole in the other side of the room. You don't
know which is the source end of the line. A directional
wattmeter reads 200 watts forward power and 200 watts
reflected power but you don't know which direction is
forward. Here's a diagram:

200W-- 2 amps--
hole-------------------50 ohm coax-------------------hole
--200W --2 amps

Which direction is the standing wave current flowing?

Lets also say that the wavelength of the waves passing through this
transmission line are as long as the room is wide (one wavelength fits
inside the room.

Then we can say that at any moment when the instantaneous magnitude of
he current is not at zero (and it will pass through zero all along the
line simultaneously, right?), the current will going in one direction
in half of that length *with varying magnitude) and the other way in
the other half (also with varying magnitude). I am not saying that
the direction reversal will necessarily be at the center, but that is
one possibility.

For example, if we took a snapshot of the current, all along the line
at the moment it peaked it might look like this:(length of arrow
represents current magnitude, and head shows direction)(view in fixed
width font)

.....--- --- -- - - -- --- --- -- - - --......
hole-------------------50 ohm coax-------------------hole

This is a snapshot of the current all along the line at an instant.

A quarter cycle later, the current would be zero, everywhere.

A half cycle later (than the first snapshot) it would look like this:

.....--- --- -- - - -- --- --- -- - - --......
hole-------------------50 ohm coax-------------------hole

This is the pattern the standing wave function describes. The current
at every point has one of two phases, which are 180 degrees from each
other.

Is this how you see it?

Current across the antenna loading coil - from scratch
 

Cecil Moore wrote:
Gene Fuller wrote:

I am feeling dizzy. I am quite comfortable with my understanding of
the entire problem, but I am seriously confused about your position.
Nobody has ever talked about efficiency or the length of wire needed.
The issue has always been replacing "degrees of antenna". I have
captured a few excerpts from April 7.


What you quoted from me is my reporting of what EZNEC says about
standing wave current Vs traveling wave current at:

http://www.qsl.net/w5dxp/travstnd.GIG

The 'x' axis for both conditions is just a piece of 1/4WL wire.
One can calculate the phase shift in any section of wire in two
ways:

1. For traveling waves, the phase shift is given by the graph
of the phase (red line). The magnitude (blue line) contains
no phase information.

2. For standing waves, the phase shift is given by taking the
arc-cosine of the magnitude (blue line). The phase (red line)
contains no phase information.

Agreed, with one exception.

There is a phase reversal each time you pass through a node, so you
can tell by phase measurement, if you are on the far end of an odd
numbered node or an even numbered node, once you decide which of the
two possibilities of the phase is at the far end of node zero (or some
other reference point). But between any pair of nodes, yes, you have
to use the phase information obtained from the ARC-COS(magnitude), or
the distance from that point to a node (as a fraction of a wavelength
in the line), to infer where you are within that half wavelength.

Of course, you can find the node either as a point with zero
magnitude, or the point between phase reversals.

Current across the antenna loading coil - from scratch
 

John Popelish wrote:
This is the pattern the standing wave function describes. The current
at every point has one of two phases, which are 180 degrees from each
other.

Is this how you see it?

Yes, now which direction is that current flowing? If the
source were known to be to the left, would that change
your answer?
--
73, Cecil http://www.qsl.net/w5dxp

Current across the antenna loading coil - from scratch
 

John Popelish wrote:

Cecil Moore wrote:
http://www.qsl.net/w5dxp/travstnd.GIF

Agreed, with one exception.
There is a phase reversal each time you pass through a node, ...

You are correct if two sides of a node exist in the system.
But since the context was my above 1/4WL wire, there is no
"passing through a node". I was limiting my statements
in context to a 1/4WL long conductor.
--
73, Cecil http://www.qsl.net/w5dxp

Current across the antenna loading coil - from scratch
 

Cecil Moore wrote:
John Popelish wrote:

This is the pattern the standing wave function describes. The current
at every point has one of two phases, which are 180 degrees from each
other.

Is this how you see it?

Yes, now which direction is that current flowing?

You deleted the arrows which I drew that showed one possible case. Do
you have some argument with what you deleted?
(I'll replace it, so you don't have to go back to look at it)
(begin paste)

For example, if we took a snapshot of the current, all along the line
at the moment it peaked it might look like this:(length of arrow
represents current magnitude, and head shows direction)(view in fixed
width font)

.....--- --- -- - - -- --- --- -- - - --......
hole-------------------50 ohm coax-------------------hole

This is a snapshot of the current all along the line at an instant.

A quarter cycle later, the current would be zero, everywhere.

A half cycle later (than the first snapshot) it would look like this:

.....--- --- -- - - -- --- --- -- - - --......
hole-------------------50 ohm coax-------------------hole
(end paste)

See all those arrows of various length representing current direction
and magnitude? Why do you ask me about something after erasing my answer?

If the source were known to be to the left, would that change
your answer?

For a pure standing wave, there is effectively a source at each end,
so this question is meaningless.