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