what happens to reflected energy ?
On 27 jun, 19:05, lu6etj wrote:
On 27 jun, 17:39, Keith Dysart wrote:
On Jun 27, 2:20 pm, K1TTT wrote:
but the equivalent points out that your statements about it sourcing
constant power is incorrect.
You might like to actually test it. The two sources are always
delivering 100W.
With an open circuit load:
The current source is delivering 100 W to the parallel source
resistor.
The voltage source delivers nothing.
Total: 100W
With a shorted load:
The voltage source is delivering 100W to the series source resistor.
The current source delivers nothing.
Total: 100W
With a 50 ohm load:
The voltage source is delivering 50W.
The current source is delivering 50W.
Total: 100W
The load is receiving 50W.
Each generator resistor is dissipating 25W.
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.
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?
I have snipped the rest of your post since until the above
is agreed, there is no sense in proceeding further.
...Keith
Sorry, *I ommited aknowledge to you I understoond your example and
what you mean with:
"What happens to Vfor1(rho) = 50v(0.7143) = 35.7v? "
"What happens to Pfor1(rho^2) = 50w(0.51) = 25.5w? "
(Last represent the cancellating (interference?) term of transmitted
power (1.Rho^2) towards generator from the reflected power from the
load to render VRef1=0 (doing the accounts with phasorial V-I math,
though I suppose will give similar results employing the eq-1 of your
World Radio article, but I am not sure if I'm catching it very well
yet. Have you P1, P2, P3 and P4, for your 100 W example, to clear
it? *)
Miguel- Ocultar texto de la cita -
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Or if you prefer, tell me if in your article: P1=48.98 W; P2=53.15 W;
P3=51.02 W; P4=51.02 W
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