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Old June 9th 10, 01:55 PM posted to rec.radio.amateur.antenna
joe joe is offline
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First recorded activity by RadioBanter: Feb 2010
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Default Question about "Another look at reflections" article.

Keith Dysart wrote:
On Jun 8, 11:27 pm, lu6etj wrote:
On 8 jun, 22:33, Keith Dysart wrote:





On Jun 8, 8:54 am, Cecil Moore wrote:
On Jun 8, 6:04 am, Keith Dysart wrote:
It is too bad, because the time domain is quite enlightening.
Nothing wrong with a time domain analysis but analyzing problems whose
basic premises violate the laws of physics is a waste of my time and
yours.
I assume that you do not consider that the problems you propose to be
ones "whose basic premises violate the laws of physics".
Consider then, the problem you propose inhttp://www.w5dxp.com/nointfr.htm.
A time domain analysis (http://sites.google.com/site/keithdysart/
radio6),
demonstrates that the analysis presented inhttp://www.w5dxp.com/nointfr.htm
results in the wrong answers.
Perhaps you could locate a flaw in the time domain analysis. Finding a
flaw
would pretty much settle the matter.
...Keith

Hi Cecil. Yes, good comment, definitions of terms specifying their
meanings in each context avoid innecessary disagreements. I think that
it is an essential predialogal "must".

Keith: I just saw your web page =http://sites.google.com/site/keithdysart/radio3
where you seems disagree (please correct me if I am wrong) with our
ideas about superposition principle. I search examples in the Net -for
not paid the price of my hard and slow translations ;)- What do you
think about them?

http://www.physics.ucla.edu/demoweb/...osition/waveSu...

http://www.phy.ntnu.edu.tw/ntnujava/...php?topic=18.0


Superposition works just fine for voltage and current, but is mostly
invalid for power. Attempting to apply superposition to power will
lead to inaccurate results.

From any circuit analysis, superposition is used to find the voltages
and the currents, and then the resulting total voltages and currents
are
used to compute powers. Doing it in the other order does not work.

I am curious as to what I wrote on the web page that suggested
disagreement with the superposition principle.

...Keith



I think the issue is the assertion there is no energy flow when I or V
is 0 is where people disagree.

I've tried to show with very simple (EE101) circuits that just because v
= 0 at some points in a circuit there is still energy flowing.

But, nobody apparently saw that.

The leap from v=0 to energy flow=0 is the source of contention. Just
because the amount of power sourced in one part of a circuit matches the
power dissipated in that portion does not mean that all the power
sourced in a portion of a circuit stayed in that portion to be
dissipated there. The whole rest of the circuit is involved.

When you do your Spice evaluation you only see the _net_ results of the
underlaying evaluation and note the _apparent_ lack of energy flow.

By selecting situations that give the results you want, you are
reinforcing the misperception. If the generators did not put out
identical pulses would you see the same lack of energy transfer?

A linear system, where superposition applies should not change based on
minor changes to the signals in it.

Limiting any analysis to steady state sine waves or uniform pulse trains
may cause you to reach the wrong conclusions.