On Jun 27, 5:49*pm, Keith Dysart wrote:
On Jun 26, 7:41*am, K1TTT wrote:



On Jun 26, 12:22*am, Keith Dysart wrote:

On Jun 25, 7:30*am, K1TTT wrote:

On Jun 25, 7:46*am, lu6etj wrote:

On 24 jun, 17:54, K1TTT wrote:

On Jun 24, 3:25*pm, Cecil Moore wrote:

On Jun 24, 9:20*am, lu6etj wrote:

Oh, I'm so sorry Cecil, I should have written "However I can not
visualize a simple PHYSICAL mechanism/example to generate
such system in a TL". Anyway, your additional info it is very useful to
me. Thanks.

The physical mechanism is the Z01==Z02 impedance discontinuity with
its associated reflection coefficient, rho. We can see that reflection
on a TDR so it is indeed a PHYSICAL mechanism.
--
73, Cecil, w5dxp.com

don't forget the OTHER physical mechanism that is necessary,
superposition... the ability to add voltages, currents, and fields in
linear circuits and media.

I mentioned same comment in another post. We use superposition
principle in two different contexts. Superposition theorem in circuit
theory, and wave superposition. Wave (traveling) superposition deals
with f(t,x,y,z) and usually with puntual magnitudes, E, H, D, B, etc)
while circuit theory deals with a subset f(t) phenomena and with
integrated magnitudes (V, I). Sometimes that becomes a confused
issue

Miguel

NO, superposition is always the same. *it is the linear addition of
currents or fields in a linear media. *it works the same for circuits
as for em waves.

the big problem are the people who confuse the formulas for adding
powers with adding fields or currents/voltages and forget the phase
terms.

the other big problem is keith who seems to want to separate his waves
into separate time and space variables and leaves out the requirement
that wave functions must be dependent on both space AND time.
basically any solution to the wave equations derived from maxwell's
laws must be of the form f(t-x/v). *this leads him to the erroneous
conclusions he gets from trying to compare his batteries to wave
propagation. *this is the same problem people have with standing
waves, they have separate dependence on t and x, so they can't travel
and can't transport energy.- Hide quoted text -

I see that the stress induced by considering DC waves is causing you
to misinterpret my writings.

May I suggest an alternate exploration for you. Assuming that you
accept TDR and know how to use Reflection Coefficients to compute
voltage and current reflections, then consider what happens
when a rectangular pulse is launched from a matched generator in
to a transmission line. For simple reflection coefficients like
0, 1, and -1 compute the reflected pulse. For both the forward
and reflected direction compute the voltage and current on the line
before the pulse arrives, as it passes and after it has passed.

Compute the energy in the pulse, and how long a distance it
occupies on the transmission line. Compute the power as the
pulse is passing.

Be sure you know what happens to the pulse when it re-enters
the generator. For simplicity, assume a generator constructed
using the Thevenin circuit.

Make sure all the results are in agreement; especially, the
energy delived by the source and the energy dissipated in the
various resistors.

Now make the pulse longer and longer... until it looks like
a step function. And do the computations again.

Determine if the results agree with those I previously
presented for the DC example.

...Keith

PS: Barring errors, they will.

why would i want to do all that work? *

It would be an opportunity for you to deepen your understanding of the
behaviour of transmission lines.

there is no way that my answers will agree with your misconceptions. *

I am not convinced. You have not yet found any errors in my
expositions,
so if you do not make any errors, I expect we will agree on the
outcome,
though perhaps not on the interpretation, for you disagree when I say
"do not assign TOO much reality to the energy in reflected waves.

You seem to want your reflected waves to always transport energy, but
are unhappy that this leads to a line that was originally excited with
a step function having energy flowing in both directions even though
the current is zero all along the line.

Cecil simply sidesteps these little inconveniences by refusing to
consider anything other than sinusoidal RF excitation and by
refusing to consider any time based analysis. Such is not the path
to understanding, deep or otherwise.

you'll just come up with an even uglier generator to try to make it fit..

My generators are pretty simple. So far I have only used 3: Thevenin,
Norton, and one with an interesting constant input power
characteristic.

oh, and by the way, your fancy 2 generator and 2 resistor 'constant
power' source isn't what you think it is. *go back to basic circuits
101 and you will find that any linear network like that can be reduced
to either a simple one source one impedance norton or thevenin
equivalent. *

You have confused a bit, models with implementation. As I said in the
original: "Consider a generator constructed as below". I am not
using an equivalent circuit, but a construction. Only when dealing
with the actual construction is it valid to examine the internal
energy flows. An "equivalent" circuit is equivalent for external
behaviour but not necessarily for internal, so I avoid them when
examining the internals.

...Keith

but the equivalent points out that your statements about it sourcing
constant power is incorrect.

i have also pointed out that your statements about your 'step wave'
are obviously incorrect because you have applied assumptions that are
only valid in the sinusoidal steady state to a step function that can
never be in steady state. neither can your pulses for that matter, so
all the assumptions are worthless, you must do the complete analysis
including the summations for the infinite fourier decomposition of
your step or pulses to get the full picture... in a transient
analysis. as was pointed out if you go VERY far into the future with
a battery connected to an open circuit piece of coax there can be no
currents and therefore no waves propagating in the line. its only in
the detailed transient analysis that you haven't done where you will
see the propagating steps going back and forth.