Jim Kelley wrote:
I don't think anyone believes that standing waves alternate in
direction.

The currents are referenced to the source. When the forward
current and reflected current are in phase at zero degrees,
they are at a maximum and flowing toward the load so their sum,
the net current, is flowing toward the load. 1/2 cycle later,
the forward current and reflected current are in phase at
180 degrees so their sum, the net current, is flowing toward
the source.

You need to think more carefully about what a standing wave is.

You need to understand that AC current flows one direction for 1/2
cycle and the opposite direction for the other 1/2 cycle. Current
cannot stand still. It must flow. And if it's AC current, it
always changes direction during the cycle. Standing current waves
are AC and neither DC nor AC current can stand still. If you install
a one ohm resistor at a current maximum point, the voltage in phase
with the current will be changing phase by 180 degrees every 1/2
cycle. The sign of the cosine of the current phase indicates direction.

It's not a matter of current flow into or current flow out of; for a
standing wave plot it's a matter of the magnitude of current flowing
*AT* the specific positions.

Current cannot flow "at" a specific position, Jim. Current has to flow
through a specific position in one of two directions. For 1/2 cycle, it
flows in one direction and for the other 1/2 cycle it flows in the opposite
direction. Like I said, the seduction by your math models is worse than I
thought.

At everywhere except the current nulls, the standing wave current changes
directions every 1/2 cycle. May I suggest you review phasor addition and
the meaning of the sign of the cosine phase when dealing with current.
--
73, Cecil, W5DXP

Tdonaly wrote:
So the coil acts precisely as if it were a capacitor. That's what capacitors
do, store and release charge. Is that what you're saying? Your coil is getting
more versatile all the time.

I am absolutely amazed at the ignorance on this newsgroup. For a resonant
tank circuit, while the cap is storing charge, the coil is releasing charge.
While the cap is releasing charge, the coil is storing charge. Doesn't
anyone understand resonance?
--
73, Cecil http://www.qsl.net/w5dxp



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Cecil Moore wrote:

Jim Kelley wrote:
I don't think anyone believes that standing waves alternate in
direction.

The currents are referenced to the source. When the forward
current and reflected current are in phase at zero degrees,
they are at a maximum and flowing toward the load so their sum,
the net current, is flowing toward the load. 1/2 cycle later,
the forward current and reflected current are in phase at
180 degrees so their sum, the net current, is flowing toward
the source.

So, now try to align that point of view with the fact that standing
waves are stationary - that current flows equally in both directions.
Combine it with the fact that there isn't a net flow of current into an
antenna. As many electrons flow "out" as flow back "in" to it.

You need to think more carefully about what a standing wave is.

You need to understand that AC current flows one direction for 1/2
cycle and the opposite direction for the other 1/2 cycle.

You need to run a diagnostic on that "logic analyzer" of yours. ;-)
It's giving you some bad readings on the available data.

Current
cannot stand still.

Profound. Note that I made no claim to the contrary.

Standing current waves
are AC and neither DC nor AC current can stand still.

Did you understand anything I wrote? You seem to be grappling with some
pretty sophomoric notions here, Cecil.

It's not a matter of current flow into or current flow out of; for a
standing wave plot it's a matter of the magnitude of current flowing
*AT* the specific positions.

Current cannot flow "at" a specific position, Jim.

:-) The plot you made on your web page shows the current flow *AT*
every position along two 1/4 wave radiators.

Like I said, the seduction by your math models is worse than I
thought.

Rainman always says he's an excellent driver. You're like him in some
ways, Cecil.

73, Jim AC6XG

Cecil wrote,

The currents are referenced to the source. When the forward
current and reflected current are in phase at zero degrees,
they are at a maximum and flowing toward the load so their sum,
the net current, is flowing toward the load. 1/2 cycle later,
the forward current and reflected current are in phase at
180 degrees so their sum, the net current, is flowing toward
the source.

(snip)

Hi Cecil,
Actually, net current doesn't flow at all in a standing wave. Current is
the rate of change of charge, dQ/dt. In a standing wave, the rate stays put.
The charge may be vibrating wildly at a point, but the average rate
of change (or even the peak, if that's what's important to you) doesn't move.
If it does move, the wave is a traveling wave, not a standing wave.
If you were right, then the rate of change of charge would alternately
move into and out of your miraculous coil. In other words, there would be
an oscillating traveling wave moving first one way and then another, into and
out of the coil, and it would do so at both ends, as in some particularly
lurid,
x-rated movie.
This is what happens when you don't understand the math, Cecil. You
make stupid mistakes based on a faulty understanding of the fundamentals.
I hate to be a fundamentalist like your minister, but I'm sure beginning to
appreciate his approach.
73,
Tom Donaly, KA6RUH

W4JLE wrote,

1. cause currect flow in a coil.
2. remove currect source.
3. Magnetic field collapses inducing voltage in the coil.
4. Doesn't it store energy in the magnetic field?

"Tdonaly" wrote in message to
Cecil...

So the coil acts precisely as if it were a capacitor. That's what
capacitors
do,
store and release charge. Is that what you're saying? Your coil is
getting
more versatile all the time.
73.
Tom Donaly, KA6RUH




I wrote "charge," not "energy." There's a difference. Cecil writes that
current, by which I think he means charge, can flow into both ends of
a coil at the same time. He's right, if he indeed is talking about charge
and not current, in which case, the charge density will increase in some
part of the coil, energy will be stored in an electric field, and the coil will

be acting just like a capacitor (with the capacitance to free space
understood).
73,
Tom Donaly, KA6RUH

Cecil
I would like to ask you a question regarding inductance coils even tho you
know I believe the current is constant
An inductor develops a field that travels thru the core
and then slays out thru 360 degrees to return to the other end of the coil.
Thes lines are directly correllated to the current flow within the
inductance and are in equilibrium
in terms of mechanical forces.
If the current is not constant thru-out the inductance
then there are more lines of force at one end than there is at the other,
such that the ends would not repel each other,one end will domimate
something I have not seen happen.
How do you account for the inbalance of the end fields
because of so called current gradient that you refer to.If there is no
imbalance what happens to dissapate the energy created by the increase of
current flow ?
I would appreciate your input on the above problem.
even tho it appears so simplistic.
Regards
Artl
i

"Cecil Moore" wrote in message
...
Art Unwin KB9MZ wrote:
Did you find something wrong with my suggestion above?

Nope, nothing "wrong". I just avoid making assertions when I'm
not 95% certain that I am correct. Thus, most of the time, I am
unresponsive. I am 95% certain that the average humongous mobile
loading coil is not "physically small" and is more like a
certain percentage of a helical antenna which indeed does
obviously demonstrate a net current gradient.
--
73, Cecil http://www.qsl.net/w5dxp



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On Thu, 05 Feb 2004 15:50:37 -0600, Cecil Moore
wrote:
The net current is the phasor sum of the forward and reflected
currents.
....
they are flowing
in opposite directions
Uh-Huh

Jim Kelley wrote:
So, now try to align that point of view with the fact that standing
waves are stationary - that current flows equally in both directions.

Are you aware that twice each cycle, the standing wave current is
zero at *every* point up and down the transmission line? If so, you
must be aware that the standing wave current changes directions
twice each cycle on each side of that zero state.

You need to run a diagnostic on that "logic analyzer" of yours. ;-)
It's giving you some bad readings on the available data.

An absolutely meaningless statement unless you are trying to create
a diversion away from the facts.

Profound. Note that I made no claim to the contrary.

Huh, you said that standing current waves stand still. Got news for
you, Jim. Standing wave current doesn't stand still. Standing current
waves reverse direction every 1/2 cycle. Take a look for yourself
with an o'scope.

Did you understand anything I wrote?

Yes, I understand that you have been seduced by your AC math model based
on a DC model. For all AC waves, including standing waves, the current
flows in the opposite directions every 1/2 cycle. I am amazed that a
physics prof doesn't understand that simple fact of physics.

Take a rope, run it through a pulley, and hold one end in each hand.
Pull on one end. The other end pulls on your other hand. That's the
way AC works. AC current reverses direction every 1/2 cycle.

:-) The plot you made on your web page shows the current flow *AT*
every position along two 1/4 wave radiators.

That's a snapshot, Jim, given by EZNEC, referenced to the source. The
current obviously changes direction and phase every 1/2 cycle in real
time. Have you never observed standing waves on an o'scope? They look
like a kid's jump rope, changing direction every 1/2 cycle. The difference
is that 'up' on the jump rope equates to 'toward the load' on a transmission
line.
--
73, Cecil http://www.qsl.net/w5dxp



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Tdonaly wrote:
Actually, net current doesn't flow at all in a standing wave.

Instantaneous standing wave current moves in one direction during
1/2 cycle, and in the opposite direction during the next 1/2 cycle.
If you think otherwise, you are simply wrong. Have you never observed
standing waves on an o'scope? It looks like a kid's jump rope.

And Tom, one of the strictest laws of physics is that current cannot
stand still. Saying that "current doesn't flow at all" is ridiculous.

When the current is flowing into both ends of the coil at the same time,
charge is being stored in the coil. 1/2 cycle later, the charge flows
out of the coil at both ends.

In one of my examples, the current at the bottom of the coil is 0.18
at - 54 degrees. The current at the top of the coil is 0.2 at 126 degrees.
Last time I checked, 54+126 = 180 degrees indicating that the current
at the bottom of the coil is 180 degrees out of phase with the current
at the top of the coil. That means the two currents are flowing in
opposite directions at the two ends of the coil.
--
73, Cecil http://www.qsl.net/w5dxp



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Tdonaly wrote:
I wrote "charge," not "energy." There's a difference. Cecil writes that
current, by which I think he means charge, can flow into both ends of
a coil at the same time. He's right, if he indeed is talking about charge
and not current, in which case, the charge density will increase in some
part of the coil, energy will be stored in an electric field, and the coil will
be acting just like a capacitor (with the capacitance to free space
understood).

Nice crawfishing job, Tom. The direction of charge flow is the same as
the direction of current flow, assuming electron current flow (as opposed
to hole current flow). If charge is flowing into each end of the coil at
the same time, then instantaneous current is, by definition, flowing into
each end of the coil at the same time for 1/2 of the RF cycle. Good to
see you coming to your senses like I knew you would.
--
73, Cecil http://www.qsl.net/w5dxp



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