On Jun 28, 5:11 pm, K1TTT wrote:
On Jun 27, 11:59 pm, Keith Dysart wrote:
I suppose, but then you have to give up on P(t)=V(t)*I(t), generally
considered to be a rather fundamental equation.

very fundamental, and very restricted. only good for one point in
space at one time, and for one pair of voltage and current
measurements... can not be applied to separate waves that are
superimposed, only to the final total voltage and current at the
measurement point at that instant.

True, but others reject it completely.

In your example, the RF energy does seem to disappear and re-appear,
when tracked on a moment by moment basis.

when doing conservation of energy you must include the WHOLE system!
it doesn't work on one section of a transmission line any more than it
works for the infamous undergraduate teaser:

take a refrigerator, put it in a perfectly insulated room, and then
open the doors... what happens to the temperature in the room?

The teaser is amusing, but hardly relevant. In my example, all of
the energy is tracked. Or, I invite you to point out that which was
overlooked. Cecil has not found any and would rather prattle on about
the difference between energy and power than actually understand.

Well, it would help if you could actually find and articulate a flaw
inhttp://sites.google.com/site/keithdysart/radio6.

...Keith

that site is rather worthless... you say Vs can be used to get the
time reference for the other signals, but time is a variable, as is
space. you seem to have a snapshot of a bunch of sine waves on an
angular scale, but is that scale time or distance?

Time, of course. I agree, though, it is not as clear as it could
have been. It helps a bit if you look at Cecil’s schematic.

Still, it is complicated and will probably take some effort to
understand.

It would probably be better to start with the step wave example
offered previously in another post and copied below for
convenience:

example
I am not sure where you think there is an error. Perhaps you can
point them out in the following example:
Generator:
- 100V step in to an open circuit
- 50 ohm source impedance
Line:
- 50 ohm
- open circuit
Generator is commanded to produce a step.
This will produce 50 V and 1 A at the line input which will
propagate down the line.
The open end of the line has a reflection co-efficient of 1.0.
Just before the 50 V step reaches the end of the line, the
whole line will be at 50 V and 1 A will be flowing everywhere.
The 50 V step hits the end and is reflected, producing a 50 V
step (on top of the 50V already there) which propagates back
to the generator. In front of the 50 V step, the current is
still 1 A (which provides the charge necessary to produce
the reverse propagating 50 V step. Behind the step, the
current is 0.
When the reverse 50 V step (which is actually a step from
50V to 100V) reaches the generator, the source impedance
matches the line impedance so there is no further reflection.
The line state is now 100V and 0A all along its length.
The settling time was one round-trip.
The generator is still producing the step, so the forward
step voltage wave is still 'flowing' and being reflected so
there is still a reflected step voltage wave, each of 50 V.
Since the generator open circuit voltage is 100 V and the
line voltage is now 100 V, current is no longer flowing
from the generator to the line.
Does this agree with your understanding?
/example

....Keith