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Re: This phase shift stuff... - Plane Wave




> Original Poster: Terry Fritz <twf-at-verinet-dot-com>
>
> Hi All,
>
>         Today I did the following experiment looking for phase shifts
along my
> secondary coil.
> <<snip>>
> So it did what I thought it would.  From my other work, I suspected this
> would be the case but I had never actually checked for the effect in this
> detailed way.  The voltage along the secondary seems to rise and fall in
> unison, just like a vibrating guitar string.  Even the harmonic seems to
> act just like a vibrating string.  No phase shift effects.  Computer models
> and calculations tell me there is a "little" phase shift (1.6 degrees) but
> that is to small for me to measure.
>
> Antonio has done measurements like this to see the nodes and antinodes but
> I am not sure he was watching the phase relationships?  I was surprised at
> his post that said:
>
> >
> >The phase goes from 0 to 90 degrees along the length of the coil.
> >But as a vertical coil over a ground plane is a somewhat non-uniform
> >transmission line, the phase may very in a somewhat nonlinear way.
> >There is no essential difference in the mechanical analogs.
> >
>
> Antonio and I seem to have completely different results!  I did not see ANY
> phase shift let alone a 90 degree shift.  Obviously, there is a little
> correlation problem here!  :-) "Real science" may be needed to find what
> the discrepancy is.  The effects are not subtle at all.  Anyone else who
> would care to try, please do!  Antonio, if you have any ideas of what might
> be wrong please let me know and we can work to resolve this.
> <<snip>>
> I really don't think now that one is going to see significant phase shifts
> unless the length of the coil is so long that the propagation effects of
> light start to have an effect.  At 1 MHz, the 1/4 lambda distance is 246
> feet so we have plenty of room!!  I would still be very interested to hear
> what the students of "FDTD (finite difference, time domain) electromagnetic
> analysis"  Jim Lux spoke of feel about all this?  They sound like they
> would be a very powerful source of knowledge on such matters…
>
> Of course, suggestions, comments, ideas… are always welcome.  I think the
> secondary coils are starting to reveal their secrets!  Apparently, they are
> far simpler that we had ever imagined.  In fact, I can't thank of anyway
> their operation could BE simpler!!  I won't miss the transmission line
> equations for one second though :-)
>
>         Terry

Terry, Jim, Antonio, All

While reading these posts I became confused about what exactly we were
discussing and realized that we may be talking apples and oranges.
Let's step back a minute and put this into perspective.

Although the SG is intermittent, for the momentary discussion let's focus
on the beat of the LC tank during the gap firing. The current in the primary
follows the voltage variation across the gap. As in any RLC circuit, there
is a
phase variance between the V and the I, but this is fixed (except for the
effect of the gap's chaotic resistance) , everybody with me so far?

Just to keep things straight, I am going to divide them up. (are you a
splitter or a lumper?)

The inductive coupling (obviously) is via the magnetid (B) field which
reaches a maximum simultaneously with I(primary), (am I still on track?)

The B field induces an EMF in the  secondary. This is where I start to see
a discrepancy. Is the effect only on the lower part of the secondary or is
the effect throughtout the secondary? This is important because of the
difference between the distance from the primary (inductive effect) and
distance from the ground (transmission line effect.) There must obviously
be some of each in every loop of the secondary. This effect of variation
of the ratio of the effects is key to finding the phase difference across the
two ends of the secondary. It is no small matter to consider the inductive
coupling of lower loops to the upper loops of the secondary as well. Is it
even possible to drive the two ends of the coil at different phases WRT
I(secondary)? Wouldn't that result in internal B field damping? Which,
ultimately, is the dominant force in the upper secondary current? The B
field of the secondary inductor itself or the distant EMF at the base? (I
will call these B dominated and E dominated cases for the rest of my post.)
This is unquestionably the salient point of the discussion. *

It is, however, not the end of the discussion (still awake?) The current,
once again, is out of phase with the voltage across the secondary. Once
again, this phase angle should not be varying. The only variation of the
voltage phase angle should be associated with self capacitance, etc.; but
this seems to be a small effect (if I have been following the threads). The
contribution by self inductance must be negligible in the E dominated
case at any rate since that was the condition that defined it. And it is not
a phase angle retardant in the B dominated case because it is the primary
source of the EMF.

The final point of consideration is the RF emanation from the coil and
it's phase relative to the varying curents and voltages. This is by no
means a trivial question. Without getting into a quantum mechanical
discussion, answering the question is almost a religious debate.

The EM radiation is, inevitably associated with dipole oscillations. Is the
only dipole of significance the potential between the top of the coil and
the ground? Will any other transient phase variance of smaller potential
and length be detectable at a distance? As long as the frequency is the
same, it should sum out in the far field; making it undetectable. Thus
any measure of the RF in the far field will not reveal localized phase
variance. Although I applaude the experiment Terry, I am not absolutely
assured that there are no loopholes.

I think fiberoptic may be critical to resolving the question irrefutably.
Even better may be an attempt to time the EMF peak arrival in the last
loop of the coil after a single pulse discharge through the primary.
( Anybody capable of timing to the picosecond? ; D )

Bryan Kaufman

*Someone with better programs than myself will have to tackle this one.
(Or, if someone already has, I apologise for my redundancy.)
The question must also be raised, does this vary with configuration of
the coil?