Cecil Moore wrote:
John Popelish wrote:
From an earlier posting: 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
x y
There is a standing wave current node at 'x' and a standing
wave current antinode (loop maximum) at 'y'. Let's say we
installed coils at those two points
....--- --- -- - - -- --- --- -- - - --......
hole--------------/////----50 ohm coax----/////------hole
x y
Now we have current flowing into both ends of the coil
located at 'x' and current flowing out of both ends of
the coil at 'y'. How does the lumped circuit model handle
that situation?
If we assume the coil is an idealized lumped inductance with no stray
capacitance at all (not a real inductor) then it would have the same
instantaneous current at each end and that current would be zero,
since it has zero size. In other words it would fit entirely in the
point that holds the node.
Real inductors with stray capacitance and imperfect magnetic coupling
for all parts of its internal current path, would have a phase shift
in the current at opposite ends, so they would have current at their
ends that was 180 degrees out of phase, if they were centered on the
node points. For half of each cycle, current would be entering each
end, and for the other half of each cycle, current would be leaving
each end. Both those currents would detour out the sides f the
inductor into displacement current through the stray capacitance of
the surface of the inductor to its surroundings.
I think (with very little actual knowledge of the software) this
conceptual model is how EZNEC handles current through a modeled
inductor and how it can have different currents at the inductor ends,
without being aware of whether those currents are driven by traveling
or standing waves. It is all based on current through inductor
segments and voltage across capacitive segments. If the segments are
small enough, it is a good approximation of a distributed solution.
Continuing with this posting:
Please don't be silly. Distributed networks have points. An infinite
number of them. Calculus is used to smoothly move through this
infinity of points. But at any particular point, current is defined
as the rate of movement of charge past that point.
No argument, but that is instantaneous current and that is NOT
the subject of this discussion. We are discussing the RMS phasor
value of current used by W8JI and W7EL for their measurements
and reported by EZNEC as in the graphic at:
I am not arguing this point. RMS values capture the amplitude of a
cycle of variation. I am inside the cycle. But the two views are
consistent.
http://www.qsl.net/w5dxp/travstnd.GIF
Please look at the standing wave current phase and tell us how
that flat phase curve can be used to measure the phase shift
in a wire or coil.
The current reported by EZNEC and measured by W8JI and W7EL is
*NOT* instantaneous current. It is RMS current. Instantaneous
current is completely irrelevant to this discussion.
I am not arguing for the validity of that measurement. Argue about it
with someone who is.
I've been waiting for that to happen. There's no point
continuing an argument with someone who denies one of
the cornerstones of EM wave theory.
So you deny that there are any points (where voltage can be defined or
that charge passes) in all distributed networks?
How strange.
:-) You have your points confused. I was talking about a logical
point. Here, let me translate for you. There's no *reason* to
continue an argument with someone who denies one of the
cornerstones of EM wave theory. John, is English your native
language? For the record, I did NOT deny the existence any
physical points!!!
The fact remains that standing wave current phase cannot
be used to measure phase delay through a wire or through
a coil. There is no phase information in standing wave
current phase.
Yes. That fact remains.
It is a non sequitur in the above discussion, however.
Whoa there, John, it is the entire reason for this discussion.
According to you, you are finished talking about coils, and want to
delve strictly into wave concepts. To honor your request, I have
tried to keep the discussion general, and avoid bringing up the effect
on and measurements of coils. But, in this post, you talk about
almost nothing else but coils. I get the distinct feeling that you
want to win a debate far more than you want to reach an understanding
with no internal contradictions. And you are willing to use dishonest
debate tactics (like telling me not to discuss a topic with you, and
then telling me that that exact topic is "the entire reason for this
discussion". Do you get beat up a lot in face-to-face arguments?
W7EL used that standing wave current phase to try to measure
phase shift through a coil. If there is no phase information
in standing wave current phase, then his entire argument
falls apart and he is back to square one with his flawed
lumped circuit model.
Yes. But I cannot concede that point of discussion for someone else.
Are you going to hit me over the head with this till every person in
the World agrees with you? I am trying to think the general case
through with you.
In case you don't realize, there is more than one person out here,
responding to you.
You remind me of a type of insanity where the sufferer thinks that
everything he is experiencing an organized illusion by a single
offending intelligence (you against the Matrix) bent on forcing him to
think that a lie is the truth, regardless of who or what he deals
with. Everyone he meets, every apparently random happenstance, the
actions of his dog and the weather, generally, are all a conspiracy to
force him to think that black is white, and he isn't going to fall for it.
If you cannot carry on a conversation with more than one person at a
time, and treat each of them as a separate mind, then this is the
wrong venue for you.