Current across the antenna loading coil - from scratch
 

On Mon, 10 Apr 2006 20:52:06 GMT, "Tom Donaly"
wrote:

Not everyone is happy with the term "displacement current." Albert
Shadowitz, in his book _The Electromagnetic Field_, has a chapter
entitled "The So-called Displacement Current." The term isn't in
the index to Feynman's _Lectures on Physics_. (At least I couldn't
find it.) All that is academic to the fact that AC current seems to
be able to make its way through a capacitor with no more opposition
than the capacitive reactance. Fortunately, no one on this
newsgroup has any objection to the way the term is commonly used.

Hi Tom, and others,

The "labeled" currents span a much too small arena. There are also
the induced currents (no, not necessarily from flux linkage) and
convection currents (which IS the primary correlative to the induced
current).

The convection currents are possibly the only current that attain the
speed of light velocity. The others are so astronomically slow, that
it is arguable to say that any current (electron/hole transport) in a
wire is any more significant than that that is supposed to never cross
through the dielectric of a capacitor.

In other words, the displacement current is labeled fictitious because
no electron ever moves from one plate to the other. Now, if we simply
substitute solid gold for that dielectric (still maintaining the same
plates); then no electron ever makes it from one plate to the other -
and yet current flows in the entire AC circuit by proportion to the
impedance presented to it by either the dielectric capacitor, or the
gold capacitor.

This, of course, illustrates the corruption of usage in the term
"current."

73's
Richard Clark, KB7QHC

Current across the antenna loading coil - from scratch
 

Gene Fuller wrote:
My point is in complete agreement with Tom, W8JI. The only thing that
allows "current taper" is displacement current.

True, but it doesn't happen as W8JI describes.

The distributed capacitance in a coil causes a transmission
line effect. The displacement currents cause delays (phase
shifts) in traveling wave currents. The traveling wave
currents can be considered to have constant magnitude, i.e.
*negligible current taper* in the traveling wave in spite
of the known displacement currents.

The displacement current effect on traveling waves is in
the phase, not the magnitude. Such is illustrated as an
EZNEC result in the left hand graphic at:

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

Please note that in spite of the distributed capacitance,
the magnitude is fixed and flat, i.e. no taper. The displacement
currents cause phase shift delays in traveling waves but has
virtually no effect on the magnitude of the traveling wave.

The distributed capacitance is the same in the transmission
line whether a single traveling wave is present or standing
waves present. So displacement currents don't necessarily
result in current taper. How do you explain that one?

Now take a look at the right hand graph involving standing
wave current. The *phase is fixed and unchanging*. The magnitude
of the standing wave current is *tapered as a cosine function
of distance from the source*. Displacement current indeed does
cause this effect but it is a transmission line effect of
superposition of forward and reflected waves, not the effect
of some imagined sideways third path for current to earth ground.
--
73, Cecil http://www.qsl.net/w5dxp

Current across the antenna loading coil - from scratch
 

Richard Harrison wrote:
"Displacement current which is the a-c current through a capacitor, that
has no a-c conduction, is not the "ONLY" thing that allows a conductor
to have a current taper." It was Tom, W8JI who shouted: "The ONLY thing
etc." I just said displacement current is NOT the only thing. Energy
level often declines between ends of a wire or coil due to losses from
radiation or dissipation in the wire or coil. Tom is mistaken.

Sorry Richard, that is not correct.

Radiation does not cause current taper. Dissipation does not either.

Consider dissipation first. If dissipation caused current reduction,
the return to a battery from a light bulb would have less current than
the outgoing terminal. There has to be a third path to allow current to
divide, but the totals of the division equal the initial amount. That's
a rule we learn way back in basic electricity. Current or charges are
not converted into heat.

Radiation is no different. Radiation is not conversion of charges into
a force that allows action at a distance. Radiation is a force on other
charges at a distance caused by charge acceleration.

The only thing that allows an antenna to have current taper or current
change along the length of a wire suspended in space is displacement
current. It is not standing waves, it is not radiation, it is not
resistance.

Of course we could add a shunt resistance or inductance to provide a
path, but when there is no leakage resistance or shunting inductance
the path can only be what is called displacement current.

A series impedance or resistance by itself, even if the cause is
radiation or loss resistance, cannot cause current reduction with
distance along a conductor.

A model that only considers reflected and forward "waves" is fine, if
applied correctly. Cecil doesn't even seem to understand current, and
appears to think there is a forward current and reflected current
moving in opposite directions at the same instant of time in the very
same location in a conductor.

Wave theory is just fine, but it has to be understood it is just a
modelling shortcut and the results cannot conflit with basic laws of
physics. The current we measure with a clamp on meter IS the current
that causes radiation, standing waves or not. It is also the current
that causes all of the heating. We cannot really have two opposite
directions of charge movement at the same time in a single conductor.

73 Tom

Current across the antenna loading coil - from scratch
 

Cecil,

All I can say is why don't you write this magic tale into a technical
article and submit it to your favorite IEEE journal or AIP journal.

73,
Gene
W4SZ

Cecil Moore wrote:
Gene Fuller wrote:

My point is in complete agreement with Tom, W8JI. The only thing that
allows "current taper" is displacement current.


True, but it doesn't happen as W8JI describes.

The distributed capacitance in a coil causes a transmission
line effect. The displacement currents cause delays (phase
shifts) in traveling wave currents. The traveling wave
currents can be considered to have constant magnitude, i.e.
*negligible current taper* in the traveling wave in spite
of the known displacement currents.

The displacement current effect on traveling waves is in
the phase, not the magnitude. Such is illustrated as an
EZNEC result in the left hand graphic at:

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

Please note that in spite of the distributed capacitance,
the magnitude is fixed and flat, i.e. no taper. The displacement
currents cause phase shift delays in traveling waves but has
virtually no effect on the magnitude of the traveling wave.

The distributed capacitance is the same in the transmission
line whether a single traveling wave is present or standing
waves present. So displacement currents don't necessarily
result in current taper. How do you explain that one?

Now take a look at the right hand graph involving standing
wave current. The *phase is fixed and unchanging*. The magnitude
of the standing wave current is *tapered as a cosine function
of distance from the source*. Displacement current indeed does
cause this effect but it is a transmission line effect of
superposition of forward and reflected waves, not the effect
of some imagined sideways third path for current to earth ground.

Current across the antenna loading coil - from scratch
 

Gene Fuller wrote:
I believe after a long series of EZNEC models and RRAA messages you came
to the conclusion that the 75 meter bugcatcher coil at 4 MHz had a
traveling wave phase shift of around 10 degrees.

Note that is not a measurement - that is what EZNEC reports but
let's assume, for the sake of discussion, that it is correct. W8JI
measured a 3nS, 4 degree phase shift in a coil twice as long with
43% more inductance. A bigger coil would obviously have a bigger
phase shift because of less current field linkage between the end
coils. So even if the phase shift through the coil is 10 degrees
as reported by EZNEC, W8JI's phase shift measurements were probably
off by *MORE THAN 200%* and that's why Tom is wrong.

This same coil resonated an antenna with a whip length of 10 feet or so.
A quarter wavelength at 4 MHz is around 60 feet. The phase shift that
could be attributed to the whip is therefore around 15 degrees. The
phase shift of the missing 50 feet of wire for a plain quarter wave
antenna would be around 75 degrees.

You are confused. Some time ago, I explained why a mobile antenna
may not be 90 degrees long at all. Did you understand that posting?
All we can say is that (Vfor+Vref)/(Ifor+Iref) is purely resistive.
We don't know how many degrees the reflected wave has traveled in
its round trip because there are too many variables.

So please stop the diversions. I have always said that the delay
through a coil *IS WHAT IT IS* but it is NOT zero and it is not the
3 nS measured by W8JI for that 100 uH coil. It is also not the near-zero
phase shift measured by W7EL using standing wave current phase as the
reference. You, yourself, implied that is an invalid measurement when
you told us there is no phase information in standing wave phase.

Seems to me you are making my argument for me and that your real
argument is with the other side. Have you told W7EL that standing
wave current phase cannot be used to measure the delay through a
coil?
--
73, Cecil http://www.qsl.net/w5dxp

Current across the antenna loading coil - from scratch
 

wrote:
Radiation does not cause current taper. Dissipation does not either.

Radiation and dissipation are considered to be losses in a
transmission line covered by the attenuation factor. All that
is needed to prove your above assertions to be false is to
quote a transmission line equation. It can even be the more
simple flat form where the SWR is 1:1. Here it is in ASCII:

I = Im*e^(ax)*e^j(wt-bx)

Note this is the equation for *CURRENT* where 'a' is the attenuation
factor. The attenuation factor includes radiation and dissipation.

Your statements indicate a high level of ignorance. Assuming a flat
transmission line with an SWR of 1:1, if the loss in the transmission
line is 3 dB, we can put 200 watts into 50 ohm coax at the source end
and get 100 watts out at the 50 ohm load end. The current out of the
source is SQRT(200w/50) = 2 amps. The current through the 50 ohm load
is SQRT(200w/50) = 1.414 amps. The current has dropped from the source
to the load by exactly the same percentage that the voltage has dropped.

What you seem to be missing is that the H-field is attenuated by the
same amount as the E-field while the ratio of E-field to H-field
remains constant and equal to Z0. Current is proportional to the
H-field and voltage is proportional to the E-field.
--
73, Cecil http://www.qsl.net/w5dxp

Current across the antenna loading coil - from scratch
 

Gene Fuller wrote:
All I can say is why don't you write this magic tale into a technical
article and submit it to your favorite IEEE journal or AIP journal.

I'm sure there are hundreds of such papers already, Gene.
Much of this stuff is in the Corum paper. But you rejected
that Corum IEEE paper that I presented as evidence so why
would me writing one make any difference to your fixed
preconceptions?
--
73, Cecil http://www.qsl.net/w5dxp

Current across the antenna loading coil - from scratch
 

Cecil Moore wrote:

wrote:

Radiation does not cause current taper. Dissipation does not either.


Radiation and dissipation are considered to be losses in a
transmission line covered by the attenuation factor. All that
is needed to prove your above assertions to be false is to
quote a transmission line equation. It can even be the more
simple flat form where the SWR is 1:1. Here it is in ASCII:

I = Im*e^(ax)*e^j(wt-bx)

Note this is the equation for *CURRENT* where 'a' is the attenuation
factor. The attenuation factor includes radiation and dissipation.

Your statements indicate a high level of ignorance. Assuming a flat
transmission line with an SWR of 1:1, if the loss in the transmission
line is 3 dB, we can put 200 watts into 50 ohm coax at the source end
and get 100 watts out at the 50 ohm load end. The current out of the
source is SQRT(200w/50) = 2 amps. The current through the 50 ohm load
is SQRT(200w/50) = 1.414 amps. The current has dropped from the source
^^^
Obviously, should be 100w. Sorry for the typo.

to the load by exactly the same percentage that the voltage has dropped.

What you seem to be missing is that the H-field is attenuated by the
same amount as the E-field while the ratio of E-field to H-field
remains constant and equal to Z0. Current is proportional to the
H-field and voltage is proportional to the E-field.
--
73, Cecil http://www.qsl.net/w5dxp

Current across the antenna loading coil - from scratch
 

Cecil,

As usual, you evaded the question, but this time you did not even do a
very slick job of evasion.

The question is what happens to the 75 degrees that was formerly
represented by the now-replaced wire. The coil may offer about 10 degrees.

I believe that Tom is stating that 75 is not equal to 10. Sounds like a
reasonable statement to me.

I don't know why you are so worried about the precise details of phase
measurements. Even your standard of precision, +/- 59%, won't make 10
equal to 75.

73,
Gene
W4SZ

Cecil Moore wrote:
Gene Fuller wrote:
I believe after a long series of EZNEC models and RRAA messages you came
to the conclusion that the 75 meter bugcatcher coil at 4 MHz had a
traveling wave phase shift of around 10 degrees.

Note that is not a measurement - that is what EZNEC reports but
let's assume, for the sake of discussion, that it is correct. W8JI
measured a 3nS, 4 degree phase shift in a coil twice as long with
43% more inductance. A bigger coil would obviously have a bigger
phase shift because of less current field linkage between the end
coils. So even if the phase shift through the coil is 10 degrees
as reported by EZNEC, W8JI's phase shift measurements were probably
off by *MORE THAN 200%* and that's why Tom is wrong.

This same coil resonated an antenna with a whip length of 10 feet or so.
A quarter wavelength at 4 MHz is around 60 feet. The phase shift that
could be attributed to the whip is therefore around 15 degrees. The
phase shift of the missing 50 feet of wire for a plain quarter wave
antenna would be around 75 degrees.

You are confused. Some time ago, I explained why a mobile antenna
may not be 90 degrees long at all. Did you understand that posting?
All we can say is that (Vfor+Vref)/(Ifor+Iref) is purely resistive.
We don't know how many degrees the reflected wave has traveled in
its round trip because there are too many variables.

So please stop the diversions. I have always said that the delay
through a coil *IS WHAT IT IS* but it is NOT zero and it is not the
3 nS measured by W8JI for that 100 uH coil. It is also not the near-zero
phase shift measured by W7EL using standing wave current phase as the
reference. You, yourself, implied that is an invalid measurement when
you told us there is no phase information in standing wave phase.

Seems to me you are making my argument for me and that your real
argument is with the other side. Have you told W7EL that standing
wave current phase cannot be used to measure the delay through a
coil?

Current across the antenna loading coil - from scratch
 

Cecil,

Wow! I think you may have set a new world record for the most irrelevant
concepts per word dragged into an RRAA posting.

We got transmission lines, attenuation factors, H-fields, E-fields, and
even SWR. Not to mention watts, dB, and Zo.

It is truly unfortunate that none of this is connected to the subject at
hand, displacement current, but it makes for a colorful message.

73,
Gene
W4SZ

Cecil Moore wrote:
wrote:

Radiation does not cause current taper. Dissipation does not either.


Radiation and dissipation are considered to be losses in a
transmission line covered by the attenuation factor. All that
is needed to prove your above assertions to be false is to
quote a transmission line equation. It can even be the more
simple flat form where the SWR is 1:1. Here it is in ASCII:

I = Im*e^(ax)*e^j(wt-bx)

Note this is the equation for *CURRENT* where 'a' is the attenuation
factor. The attenuation factor includes radiation and dissipation.

Your statements indicate a high level of ignorance. Assuming a flat
transmission line with an SWR of 1:1, if the loss in the transmission
line is 3 dB, we can put 200 watts into 50 ohm coax at the source end
and get 100 watts out at the 50 ohm load end. The current out of the
source is SQRT(200w/50) = 2 amps. The current through the 50 ohm load
is SQRT(200w/50) = 1.414 amps. The current has dropped from the source
to the load by exactly the same percentage that the voltage has dropped.

What you seem to be missing is that the H-field is attenuated by the
same amount as the E-field while the ratio of E-field to H-field
remains constant and equal to Z0. Current is proportional to the
H-field and voltage is proportional to the E-field.

Current across the antenna loading coil - from scratch
 

Cecil Moore wrote:
Michael Coslo wrote:

Not that I could fan the flames any more anyhow, but just what was the
original discussion about anyhow?


As I realized what the actual misconception really is, the discussion
shifted from coils to standing waves. Seems to me, W8JI and W7EL do
not understand the difference implied by these two different equations
(assuming |Ifor|=|Iref|).

Ifor = I1*cos(kx+wt) and Iref = I1*cos(kx-wt)

Istnd = I1*cos(kx+wt) + I1*cos(kx-wt) = I2*cos(kx)*cos(wt)

Gene Fuller has kindly explained the difference but W8JI and W7EL
seemed to have ignored his explanation. Gene says there is no
phase information in standing wave current phase and I agree.




I've said it before and I'll say it again, there is no phase variable
in I1*cos(kx+wt) and there is no phase variable in I1*cos(kx-wt) so
there can't possibly be any phase information in 2*I1*cos(kx)*cos(wt).
If you're going to measure a phase difference between two places on
a transmission line and you want to write an equation describing what
you're doing, you have to have the phase variable somewhere in your
equation so you can solve for it. Also, it would help, Cecil, if you
would be a little more careful when you copy these equations from your
favorite Bible. They keep changing form as time passes.
73,
Tom Donaly, KA6RUH

Current across the antenna loading coil - from scratch
 

Cecil Moore wrote:

Tom Donaly wrote:

Not everyone is happy with the term "displacement current." Albert
Shadowitz, in his book _The Electromagnetic Field_, has a chapter
entitled "The So-called Displacement Current." The term isn't in
the index to Feynman's _Lectures on Physics_. (At least I couldn't
find it.) All that is academic to the fact that AC current seems to
be able to make its way through a capacitor with no more opposition
than the capacitive reactance. Fortunately, no one on this
newsgroup has any objection to the way the term is commonly used.


Here's an associated quote from "Electromagnetic Engineering"
by R.W.P King: "an adequate representation of the reactance
of a coil with a nonuniformly distributed current is NOT
POSSIBLE in terms of a coil with a uniform current [a lumped-
element inductance] connected in parallel with a lumped
capacitance."

I don't know what that has to do with displacement current, Cecil,
but if you're worried about it you can just use your coil at a frequency
where you get a more satisfactory current distribution. I made a coil
like you talk about (mine was 5.25 inches long,
27 turns, 6 inches in diameter) and it behaved pretty much like
a coil in parallel with a capacitor up to a few megahertz, at least.
Beyond that, it was a different story.
73,
Tom Donaly, KA6RUH

Current across the antenna loading coil - from scratch
 

Gene Fuller wrote:
It is truly unfortunate that none of this is connected to the subject at
hand, displacement current, but it makes for a colorful message.

Please don't tell us that you don't understand how the attenuation
factor in a transmission line current equation causes the current
to drop along the line equaling the percentage drop in the voltage.

One can write a similar equation for a standing wave dipole.
--
73, Cecil http://www.qsl.net/w5dxp

Current across the antenna loading coil - from scratch
 

Tom, W8JI wrote:
"Wave theory is just fine, but it has to be understood it is just a
modeling shortcut and the results cannot conflict with the basic laws of
physics,"

The Quantum theory may replace the wave theory some day, but the wave
theory has always satisfied my needs.

Terman writes on page 84 of his 1955 edition:
"The quantity aq. rt. of ZY is called the propagation constant of the
line. It is a complex quantity, having a real part alpha called the
attenuation constant and an imaginary part beta termed the phase
constant."

On the next page 85, Terrman has diagrams showing behavior of the
voltages of the incident and reflected waves on a transmission line. It
is the same as that on antennas. That`s why the antenna section of
Terman`s book tells the reader to refer to the transmission line chapter
for the behavior of antennas. It`s identical.

I`ve erected and operated countless rhombics in the international
broadcasting service. I`ve underloaded them and overloaded them and in
the process melted plenty of dissipation lines. I can attest that Terman
has it right. Sometimes you have to do what you`ve got to do even when
you know better.

When the dissipation line went away we would cover outh America as well
as Central Europe and get lots of fan mail for our troubles. We
shouldn`t have been getting fan mail from South America but lots of
Central Europeans were living there as refugees from the Axis and from
the Allies. When we covered South America, some broadcaster with a valid
claim on the frequency at that hour and place was being clobbered by
us.. We couldn`t help it. Our job was to save the world and we did it
while sometimes stepping on others in the process.

I guarantee we never put anything even close to 100KW into a dissipation
line. Problem was the Signal Corps rhombic kits were maxed out at 5 KW
and it took time to get bigger resistance wire. 100 KW in a dissipation
line would have melted it in days if not sooner. As it was, standard
G.I. lines lasted weeks while glowing a cheerful red and did not erupt
in a blinding flash.

The wave travels along both wires simultaneously. The wires in the
dissipation line melt at the input end not at the far end where the wire
is smaller. Current does not travel through the line like the utility
power frequency through a string of Christmas tree lights.

Tom needs to get with the reality of the program. His idea is seriously
flawed.

Best regards, Richard Harrison, KB5WZI

Current across the antenna loading coil - from scratch
 

Tom Donaly wrote:
I've said it before and I'll say it again, there is no phase variable
in I1*cos(kx+wt) and there is no phase variable in I1*cos(kx-wt) so
there can't possibly be any phase information in 2*I1*cos(kx)*cos(wt).

Sorry, you are wrong about that. EZNEC reports that phase information.
Assuming the EZNEC default convention, the source is 1.0 amp at zero
degrees at t=0. So the RMS value of the traveling wave current is
1.0 amp at -'kx' degrees. -'kx' *IS* the phase angle of the current
up and down the wire referenced to the source. It is negative because
the source naturally leads the traveling wave.

Note 'kx' is how far the point of interest is away from the source
in degrees.

Doesn't anyone understand phasors anymore?
--
73, Cecil http://www.qsl.net/w5dxp

Current across the antenna loading coil - from scratch
 

Cecil Moore wrote:
John Popelish wrote:

If you have no interest in anything but butting heads with the people
who have disagreed with you, then, please stop responding to my posts.

If you are into playing games, you are responding to the
wrong person. Try W8JI or W7EL instead.

Heck, Cecil, you had years of participation in r.r.a.p. during which you
were a pregnant man, a 300 foot tall alien or you were challenging
others to dunk a basketball. I'd say that game playing is one of your
favorite things.

Dave Heil K8MN

Current across the antenna loading coil - from scratch
 

Dave Heil wrote:
Heck, Cecil, you had years of participation in r.r.a.p. during which you
were a pregnant man, a 300 foot tall alien or you were challenging
others to dunk a basketball. I'd say that game playing is one of your
favorite things.

Wow, what a memory. :-)
--
73, Cecil http://www.qsl.net/w5dxp

Current across the antenna loading coil - from scratch
 

Gene Fuller wrote:
The question is what happens to the 75 degrees that was formerly
represented by the now-replaced wire. The coil may offer about 10 degrees.

I believe that Tom is stating that 75 is not equal to 10. Sounds like a
reasonable statement to me.

No argument from me. Obviously you didn't understand my previous
explanation that a resonant mobile antenna doesn't have to be 90
degrees long - something I explained weeks ago. Therefore, the coil
doesn't have to be 75 degrees. Please re-read my postings again below
until you understand what I said.

Think of all the possibilities that make (Vfor+Vref)/(Ifor+Iref)
purely resistive without any one of those terms being in phase with
any other of those terms. Then you will realize why that mobile
antenna is probably not 90 degrees long at all.

In my earlier posting, I gave values of phase that make the feedpoint
purely resistive without any one of those terms being in phase with
any other one of those terms.

BOTTOM LINE: Until you can prove that a mobile antenna is 90
degrees long, your argument is just another straw man. What is it
about my following previous statements that you don't understand?

W5DXP wrote:
You are confused. Some time ago, I explained why a mobile antenna
may not be 90 degrees long at all. Did you understand that posting?
All we can say is that (Vfor+Vref)/(Ifor+Iref) is purely resistive.
We don't know how many degrees the reflected wave has traveled in
its round trip because there are too many variables.

So please stop the diversions. I have always said that the delay
through a coil *IS WHAT IT IS* but it is NOT zero and it is not the
3 nS measured by W8JI for that 100 uH coil. It is also not the near-zero
phase shift measured by W7EL using standing wave current phase as the
reference. You, yourself, implied that is an invalid measurement when
you told us there is no phase information in standing wave phase.

Seems to me you are making my argument for me and that your real
argument is with the other side. Have you told W7EL that standing
wave current phase cannot be used to measure the delay through a
coil?
--
73, Cecil http://www.qsl.net/w5dxp

Current across the antenna loading coil - from scratch
 

On Mon, 10 Apr 2006 23:05:48 -0400, "Yuri Blanarovich"
wrote:

You don't want to explain W5DXP models and answer his questions.

Yuri,

Even YOU cannot explain his models or answer his questions!

On Tue, 11 Apr 2006 04:08:34 GMT, Cecil Moore
wrote:

BOTTOM LINE: Until you can prove that a mobile antenna is 90
degrees long, your argument is just another straw man.

Are you guys on the same planet?

Now don't get me wrong, I enjoy the comedy all the same and your Punch
and Judy act keeps us all entertained, but don't confuse the applause
as nominations for the Nobel Prize in Physics.

73's
Richard Clark, KB7QHC

Current across the antenna loading coil - from scratch
 

Richard Harrison wrote:

The wave travels along both wires simultaneously. The wires in the
dissipation line melt at the input end not at the far end where the wire
is smaller. Current does not travel through the line like the utility
power frequency through a string of Christmas tree lights.

Tom needs to get with the reality of the program. His idea is seriously
flawed.

I take it you are saying you think current can flow two directions at
the same instant of time in a conductor, can be "lost" from a single
conductor through radiation and resistance without a shunting
impedance, conservation of charge isn't important, and Maxwell's
equations are wrong.

You know that because you installed antennas at one point in your life.
Is that correct or did I misunderstand your post?

73 Tom

Current across the antenna loading coil - from scratch
 

Richard Harrison wrote:
Tom, W8JI wrote:
"Wave theory is just fine, but it has to be understood it is just a
modeling shortcut and the results cannot conflict with the basic laws of
physics,"

The Quantum theory may replace the wave theory some day, but the wave
theory has always satisfied my needs.

W8JI is confused above. Wave theory, i.e. the distributed network
model, is not much of a modeling shortcut. The lumped-circuit
model is the actual shortcut and is a subset of the distributed
network model. The lumped-circuit model conflicts much more
with Maxwell's laws than does the distributed network model
which conflicts hardly at all.
--
73, Cecil http://www.qsl.net/w5dxp

Current across the antenna loading coil - from scratch
 

wrote:
I take it you are saying you think current can flow two directions at
the same instant of time in a conductor, can be "lost" from a single
conductor through radiation and resistance without a shunting
impedance, conservation of charge isn't important, and Maxwell's
equations are wrong.

EM energy is certainly flowing in two directions because it is
a standing wave antenna. The forward current phasor is proportional
to the forward H-field. The reflected current phasor is proportional
to the reflected H-field. The two H-fields are superposed. That is
the same thing as adding the two current phasors.

Quoting Balanis: "Standing wave antennas, such as the dipole,
can be analyzed as traveling wave antennas with waves propagating in
opposite directions (forward and backward) and represented by
traveling wave antenna currents I(f) and I(b)."

W8JI says an antenna cannot be analyzed in that way. Who are we
to believe? Balanis or W8JI?

Balanis gives us permission to analyze two currents flowing in opposite
directions at the same time. After all, the superposition principle
allows us to do that. I'm sure Dr. Balanis would like to hear your
argument to the contrary.

Kraus agrees with Balanis and disagrees with you. "A sinusoidal
current distribution may be regarded as the standing wave produced
by two uniform (unattenuated) traveling waves of equal amplitude
moving in opposite directions along the antenna."

W8JI says it cannot be regarded in such terms. Who are we to
believe? Kraus or W8JI?

... can be "lost" from a single
conductor through radiation and resistance without a shunting
impedance, conservation of charge isn't important, and Maxwell's
equations are wrong.

All we are saying is that the currents drops the same percentage
amount as does the voltage. Voltage and current share the same
identical attenuation factor. The E-field and H-field drop by the
same percentage. If your model absolutely requires a shunt
impedance, it can be found in the distributed LCLCLCLCLC model
of a transmission line.

Conservation of charge and conservation of energy are inviolate.

Maxwell's equations, as opposed to the flawed lumped-circuit model,
are correct. The distributed network model is a lot more like
Maxwell's equations than is the lumped-circuit model.
--
73, Cecil http://www.qsl.net/w5dxp

Current across the antenna loading coil - from scratch
 

Cecil Moore wrote:
Gene Fuller wrote:

The question is what happens to the 75 degrees that was formerly
represented by the now-replaced wire. The coil may offer about 10
degrees.


I believe that Tom is stating that 75 is not equal to 10. Sounds like
a reasonable statement to me.


No argument from me.


Cecil,

Does that end the thread? Or do you plan to keep expanding into unknown
territory where only your strawman lives?

73,
Gene
W4SZ

Current across the antenna loading coil - from scratch
 

Gene Fuller wrote:
Does that end the thread?

Does agreeing that 75 is not equal to 10 end the thread?
Of course not. That posting *ASSUMED FOR THE SAKE OF
DISCUSSION* that EZNEC was reporting the actual delay
through the coil. I suspect it is not reporting the
actual delay because reflections are still present
inside the coil. The characteristic impedance changes
abruptly at the top of the coil so that would be no
surprise at all.

We know EZNEC blindly reports the net current that is
there. If we, as modelers, don't eliminate reflections,
EZNEC will not correctly report the traveling wave phase
shift. In our naivete', we didn't eliminate reflections.

75 degrees is probably not correct. 10 degrees is
probably not correct. Why do you want to quit before
the correct answer has been found?

************************************************** *
Here's a more valid procedure for determining the
delay through a coil. Changing nothing except the
number of turns, add turns until the coil is self-
resonant at the frequency of use. Frequency doesn't
change. Coil diameter doesn't change. Turns per inch
doesn't change. The *ONLY* thing that changes is the
length of the coil. At self-resonance, we *know* the
longer coil is 90 degrees long.
************************************************** *

Take that same 32 turn coil and keeping everything the
same, add turns to the coil until it is self-resonant.
We haven't changed the frequency, the diameter, or the
turns per inch. All we have done is add 37 turns to the
original 32 turn coil to make the self-resonant frequency
equal to 4 MHz with 69 turns. SINCE WE HAVEN'T CHANGED
THE FREQUENCY, WE KNOW THAT THE VELOCITY FACTOR OF THE
COIL HAS NOT CHANGED.

In the velocity factor equation, the only variables are
coil diameter, turns per inch, and wavelength. NONE OF
THOSE VARIABLES ARE CHANGED ABOVE.

So we know that 69 turns makes that coil stock self-resonant
at 4 MHz. That would make the phase shift through 32 turns
equal to 42 degrees, making our above 10 degree assumption
false. 42 degrees is probably fairly close to the actual value.
The velocity factor for that coil stock calculates out to
be 0.023 on 4 MHz.

The delay through a coil is what it is. The only valid side
to this argument are technical facts, valid measurements,
and valid modeling.
--
73, Cecil http://www.qsl.net/w5dxp

Current across the antenna loading coil - from scratch
 

Cecil Moore wrote:
Tom Donaly wrote:

I've said it before and I'll say it again, there is no phase variable
in I1*cos(kx+wt) and there is no phase variable in I1*cos(kx-wt) so
there can't possibly be any phase information in 2*I1*cos(kx)*cos(wt).


Sorry, you are wrong about that. EZNEC reports that phase information.
Assuming the EZNEC default convention, the source is 1.0 amp at zero
degrees at t=0. So the RMS value of the traveling wave current is
1.0 amp at -'kx' degrees. -'kx' *IS* the phase angle of the current
up and down the wire referenced to the source. It is negative because
the source naturally leads the traveling wave.

Note 'kx' is how far the point of interest is away from the source
in degrees.

Doesn't anyone understand phasors anymore?

You missed the point again, Cecil. Carry on.
73,
Tom Donaly, KA6RUH

Current across the antenna loading coil - from scratch
 

Tom Donaly wrote:

Cecil Moore wrote:
Doesn't anyone understand phasors anymore?

You missed the point again, Cecil. Carry on.

The point is that there is phase information in the
traveling wave equation. -'kx' *IS* the phase and
is reported by EZNEC at:
http://www.qsl.net/w5dxp/travstnd.GIF
--
73, Cecil http://www.qsl.net/w5dxp

Current across the antenna loading coil - from scratch
 

Richard Harrison wrote:
Tom, W8JI wrote:
"I take it you are saying you think current can flow two directions at
the same instant of time in a conductor through radiation and resistance
without a shunting impedance, conservation of charge isn`t important,
and Maxwell`s equarions are wrong."

That`s the wrong take.

Maxwell works for me even if there is no aether.

Anntennas work in free space without a ground but it is hard to
duplicate free space conditions at high and lower frequencies here on
earth.

Every standing-wave antenna has a reflection caused by an impedance
discontinuity at wire`s end. At this point, a reflection begins its
travel back toward the generator. By the time the reflection arrives at
the generator, every point on the wire has current flowing in both
directions simultaneously. No shunting capacitance to earth or anyplace
else is needed to conserve charge. The wire is self-sufficient.

Radiation resistance is a convenience defined as the resistance which if
placed in series with an antenna would consume the same power that the
antenna is radiating.

At every point along an antenna with a reflection, current is flowing in
two directions at the same time.

Best regards, Richard Harrison, KB5WZI


Completely wrong, as usual. There is nothing in the natural world
that can double itself and go two opposite directions at the same
time. In order to do so it would have to violate the principle of
the conservaton of charge. At any instant, the charge at a point
has to be going either one direction or another which you can
confirm using the wave equation which Cecil doesn't understand
any more than you do. Superposition is a fine principle, but
like any intellectual tool it has to be understood to be used
properly.
73,
Tom Donaly, KA6RUH

Current across the antenna loading coil - from scratch
 

Cecil Moore wrote:

Tom Donaly wrote:

Cecil Moore wrote:

Doesn't anyone understand phasors anymore?


You missed the point again, Cecil. Carry on.


The point is that there is phase information in the
traveling wave equation. -'kx' *IS* the phase and
is reported by EZNEC at:
http://www.qsl.net/w5dxp/travstnd.GIF

You still don't get it.
73,
Tom Donaly, KA6RUH

Current across the antenna loading coil - from scratch
 

Richard H.,
He is stuck on DC in a coil. Tom did not discover Standing Waves,
Impedances, Currents, Voltages in RF circuits, antennas, feedlines.
Helooooo! IT'S RF and standing waves along the resonant antenna and things
to do with RF energy along them radiators, like sin and cos distribution of
voltage and current. Which show that current and voltage can be ZERO along
the conducting wire, aka antenna. First he used Kirchoff, now is Maxwell to
the "rescue" to muddy the waters.
Maybe we should apply for him for vanity callsign WR0NG :-)

Yuri, K3BU


wrote in message
oups.com...
Richard Harrison wrote:

The wave travels along both wires simultaneously. The wires in the
dissipation line melt at the input end not at the far end where the wire
is smaller. Current does not travel through the line like the utility
power frequency through a string of Christmas tree lights.

Tom needs to get with the reality of the program. His idea is seriously
flawed.

I take it you are saying you think current can flow two directions at
the same instant of time in a conductor, can be "lost" from a single
conductor through radiation and resistance without a shunting
impedance, conservation of charge isn't important, and Maxwell's
equations are wrong.

You know that because you installed antennas at one point in your life.
Is that correct or did I misunderstand your post?

73 Tom

Current across the antenna loading coil - from scratch
 

Could you please enlighten us, Cecil, exactly why you think that
anything in all of W8JI's full posting referenced by reference below
where he implicitly or explicitly says anything at all about a lumped
model, or about lumped behaviour? After a careful search, I'm unable
to find it. I only find a discussion of distributed behaviour in a
circuit which extends beyond near field.

Cheers,
Tom

(On the other hand, all the wave and field theory I know was developed
to explain and model the forces among charges, and the reaction--the
motion and accumulation--of those charges as a result of those forces.
That's EXACTLY what I DO see W8JI writing about in the referenced
posting.)


==========
Cecil wrote in a message whose ID can be provided upon request,
Richard Harrison wrote:
Tom, W8JI wrote:
"Wave theory is just fine, but it has to be understood it is just a
modeling shortcut and the results cannot conflict with the basic laws of
physics,"

The Quantum theory may replace the wave theory some day, but the wave
theory has always satisfied my needs.

W8JI is confused above. Wave theory, i.e. the distributed network
model, is not much of a modeling shortcut. The lumped-circuit
model is the actual shortcut and is a subset of the distributed
network model. The lumped-circuit model conflicts much more
with Maxwell's laws than does the distributed network model
which conflicts hardly at all.
--
73, Cecil http://www.qsl.net/w5dxp

Current across the antenna loading coil - from scratch
 

Tom Donaly, KA6RUH wrote:
"There is nothing in the natural world that can double itself and go in
the opposite direction at the same time."

Watch water waves slam into a bulkhead and you can see the reflected
waves interfere with the incident waves as they travel in the opposite
directions.

Electrical waves, incident and reflected, pass through each other too.
In the antenna or transmission line, the charge is impelled by the
energy supplied by the generator to move back and forth on the surface
of the wire at the radio frequency rate.

The incident wave and the reflected wave on a transmission line travel
in opposite directions. At certain points along the line the voltages in
the waves will be in phase and will add, while in other points they will
be out of phase and subtract. The points along the line where the two
voltages are in phase are points of maximum voltage and minimum current
and are spaced one half wavelength apart. The points along the line
where the two voltages are 180-degrees out of phase are points of
minimum voltage and maximum current and are also one half wavelength
apart. The distance between alternate points is one-quarter wavelength.

The reflection of a radio wave is a natural occurrence. When the voltage
produced by the incident wave hits the open-circuit of a wire it doubles
itself and starts a wave propagating in the opposite direction while the
incident waves are yet arriving at the open-circuit.

Best regards, Richard Harrison, KB5WZI

Current across the antenna loading coil - from scratch
 

Tom Donaly wrote:
Richard Harrison wrote:

Tom, W8JI wrote:
"I take it you are saying you think current can flow two directions at
the same instant of time in a conductor through radiation and resistance
without a shunting impedance, conservation of charge isn`t important,
and Maxwell`s equarions are wrong."

That`s the wrong take.

Maxwell works for me even if there is no aether.

Anntennas work in free space without a ground but it is hard to
duplicate free space conditions at high and lower frequencies here on
earth.

Every standing-wave antenna has a reflection caused by an impedance
discontinuity at wire`s end. At this point, a reflection begins its
travel back toward the generator. By the time the reflection arrives at
the generator, every point on the wire has current flowing in both
directions simultaneously. No shunting capacitance to earth or anyplace
else is needed to conserve charge. The wire is self-sufficient.

Radiation resistance is a convenience defined as the resistance which if
placed in series with an antenna would consume the same power that the
antenna is radiating.

At every point along an antenna with a reflection, current is flowing in
two directions at the same time.

Best regards, Richard Harrison, KB5WZI


Completely wrong, as usual. There is nothing in the natural world
that can double itself and go two opposite directions at the same
time. In order to do so it would have to violate the principle of
the conservaton of charge. At any instant, the charge at a point
has to be going either one direction or another which you can
confirm using the wave equation which Cecil doesn't understand
any more than you do. Superposition is a fine principle, but
like any intellectual tool it has to be understood to be used
properly.
73,
Tom Donaly, KA6RUH

Tom

Have you ever sloshed water in a bowl? If you had you would have seen
wave forms going in both directions. First the initial wave crosses the
bowl then reflects off the side of the bowl and returns in the opposite
direction.
This is the same as an EMF wave in an antenna. No violation of any
principles of conservation, in fact it is demanded of the principle.

Dave WD9BDZ

Current across the antenna loading coil - from scratch
 

Cecil Moore wrote:


Here's a more valid procedure for determining the
delay through a coil.

Cecil,

So you think adding turns to a coil is a nice linear process that allows
you to then subdivide the resonance effects according the number of
turns in each subsection?

That's a good one. I almost injured myself laughing when I read it.

73,
Gene
W4SZ

Current across the antenna loading coil - from scratch
 

Tom Donaly wrote:
There is nothing in the natural world
that can double itself and go two opposite directions at the same
time.

Seems your ignorance also extends to entangled particles?

In order to do so it would have to violate the principle of
the conservaton of charge.

This is simply one more example of the seduction of other-
wise intelligent people by the lumped-circuit model's
unproven presuppositions.

You are confusing charge with EM wave energy. If two EM light
waves traveling in opposite directions can cause a standing
wave in empty space, then so can two RF waves traveling in
opposite directions in space or around a wire. There is no
requirement for current at all. Current is a left over
artifact from the DC model. In fact, it can be proven
that virtually all of the energy (power) exists solely in
the two EM waves surrounding the wire and virtually none in
the conductor. All that is required for standing waves is
E-fields and H-fields traveling in opposite directions WHETHER
A WIRE EXISTS OR NOT.

If everyone were using Maxwell's equations instead of flawed
simplified models, none of this confusion would exist. All
of the energy is in the waves and none in the current or
voltage. After all, E x H is the *total power* in a wave.
There is no extra energy left over to support voltage and
current.
--
73, Cecil http://www.qsl.net/w5dxp

Current across the antenna loading coil - from scratch
 

David G. Nagel wrote:

Tom

Have you ever sloshed water in a bowl? If you had you would have seen
wave forms going in both directions. First the initial wave crosses the
bowl then reflects off the side of the bowl and returns in the opposite
direction.
This is the same as an EMF wave in an antenna. No violation of any
principles of conservation, in fact it is demanded of the principle.

Dave WD9BDZ


Dave,

You have highlighted a misconception that is common and a great cause of
confusion in this forum.

Yes, the "waves" can do what you say. However, the "waves" are merely
mathematical descriptions of the underlying physical phenomena. There is
simply no such thing as a "wave" all by itself. Instead there are water
waves, electromagnetic field waves, guitar string waves, sound waves,
and so on.

Nature tends to be single valued, at least in the ordinary classical
world. At any specific point in time and space there is only one value
of current, one value of electric field, one value for the motion of a
particle (water molecule, guitar string molecule, etc.), one charge
density, and so on. These values can and do change with differences in
time and space. However, the physical entities do not have two values at
once in the same time and place.

73,
Gene
W4SZ

Current across the antenna loading coil - from scratch
 

Cecil,

Are you practicing your stand-up comedy routine? You are in rare form today.

Why didn't you set us straight about 3000 messages ago? If only we knew
that RF current was a mere artifact we could have shortened this thread
to one message.

73,
Gene
W4SZ

Cecil Moore wrote:

You are confusing charge with EM wave energy. If two EM light
waves traveling in opposite directions can cause a standing
wave in empty space, then so can two RF waves traveling in
opposite directions in space or around a wire. There is no
requirement for current at all. Current is a left over
artifact from the DC model. In fact, it can be proven
that virtually all of the energy (power) exists solely in
the two EM waves surrounding the wire and virtually none in
the conductor. All that is required for standing waves is
E-fields and H-fields traveling in opposite directions WHETHER
A WIRE EXISTS OR NOT.

If everyone were using Maxwell's equations instead of flawed
simplified models, none of this confusion would exist. All
of the energy is in the waves and none in the current or
voltage. After all, E x H is the *total power* in a wave.
There is no extra energy left over to support voltage and
current.

Current across the antenna loading coil - from scratch
 

K7ITM wrote:
Understanding the congrence among many methods/theories is a very nice
thing, for it gives one confidence that they are correct, and the
ability to apply the one that's most convenient to any particular
problem. I would not want to take away wave theory, or any other valid
theory, from you; I would only ask that you better understand that your
pet is not the ONLY valid explanation.

The point is that in any disagreement between the lumped-circuit
model and a properly applied distributed network model, the
lumped-circuit model loses *EVERY* time since the lumped-circuit
model is a *SUBSET* of the distributed network model.

If your current charge concepts disagree with Maxwell's equations,
Maxwell's equations win *EVERY* time. Maxwell's equations do not
require individual charge carriers. They work just fine considering
only fields in the aether.
--
73, Cecil http://www.qsl.net/w5dxp

Current across the antenna loading coil - from scratch
 

K7ITM wrote:
Could you please enlighten us, Cecil, exactly why you think that
anything in all of W8JI's full posting referenced by reference below
where he implicitly or explicitly says anything at all about a lumped
model, or about lumped behaviour? After a careful search, I'm unable
to find it. I only find a discussion of distributed behaviour in a
circuit which extends beyond near field.

W8JI is right 99% of the time. I agree with him on those
things as do you. Your above posting is no surprise.

Here's one of W8JI's statements. Please defend it.

W8JI said:
Radiation does not cause current taper. Dissipation does not either.

What is contained in the attenuation factor for the current
transmission line equation if not radiation and dissipation?
What else is there?
--
73, Cecil http://www.qsl.net/w5dxp

Current across the antenna loading coil - from scratch
 

Gene Fuller wrote:
So you think adding turns to a coil is a nice linear process that allows
you to then subdivide the resonance effects according the number of
turns in each subsection?

That appears to me to be the most valid measurement that we
can make of the delay through a coil. If you have a better
way, please present it.
--
73, Cecil http://www.qsl.net/w5dxp

Current across the antenna loading coil - from scratch
 

Gene, W4SZ wrote:
"However, the physical entities do not have two values at once in the
same time and place."

You can measure each of the two simultaneous constituents with the right
equipment. A Bird Thruline wattmeter uses a directional coupler to
separate forward direction power from reverse direction power. These are
obbtainable at the same time and place anywhere in a 50-ohm coax line.
Individual volts and amps in each direction are easily calcuable from
the powers indicated in each direction.

Best regards, Richard Harrison, KB5WZI