Re: Is the Superposition Principle invalid?

Cecil Moore <nospam@xxxxxxxxx> wrote in news:p7iPh.3356$YL5.856
@newssvr29.news.prodigy.net:

Owen Duffy wrote:
Cecil, would you state the superposition principle as you know it?

I'll just quote Hecht on that. He gives the three
dimensional differential wave equation and follows it
up with a linear combination of individual waves in
an equation that cannot be reproduced here and says,

"Known as the *Principle of Superposition*, this property
suggests that the resultant disturbance at any point in a
medium is the algebraic sum of the separate constituent
waves."

The unreproducible equation essentially says that the
total wave function is equal to the algebraic sum of
the individual wave functions.

Hecht goes on to treat the forward wave and reflected
wave as the "separate constituent waves", something
that we have been told by the "reflected waves don't
exist" gurus on this newsgroup, is an invalid thing
to do.

It seems to me that the superposition principle gives us
permission to consider the forward and reflected waves
separately and "algebraically sum" the results. That is
exactly what the S-Paramater analysis is based upon.
The S-Parameter analysis considers a1 to be the incident
forward wave and a2 to be the incident reflected wave.
They are treated separately and then "algebraically
summed"

Cecil, this is not a complete definition, and you have not related it to
the subject under discussion, tranmission lines, and the quantities that
are being discussed.

To my mind, there is nothing in YOUR definition above (it is not Hecht's,
it is your partical quote and elaboration) that states that it is valid
to sum energy waves or power waves (whatever those terms mean) as you
seem to want to do, or to treat them independently if that is what
'separately' means as you use it, or the specifics of what quantities are
summed.

Several people have been freely writing expressions that take the
algebraic sum of phasor quantities Vf and Vr, and If and Ir. You are
citing and partially quoting obscure sources not directly relevant to the
subject to justify your summation of energy waves or power waves or
whatever you are calling them today.

Sit down and write a complete definition of your knowledge of the
"Superposition Principle" as you understand it using quantities
encountered in a transmission line analysis, like voltage, current,
power.

Owen
.

Relevant Pages

  • Re: Mismatched Zo Connectors
    ... "Contrary to popular views, the forward and reverse ... waves on a transmission line are not separate fields." ... for transmission lines as presented by Ramo/Whinnery, ...
    (rec.radio.amateur.antenna)
  • Re: Preposterous change of variables
    ... Now here is where it ties in to where you helped me before. ... separate using waves ... But when I separate using ... The main problem is that you really can't properly interpret the ...
    (sci.physics)
  • Re: Biosignal Classification
    ... Presumably this is relevant to the shape of your waves, ... In other words, if you take sub-samples and calculate the variance, ... analysis to separate it into the states. ...
    (comp.soft-sys.matlab)
  • Re: final results
    ... not sure how many waves and what was the interval gap. ... True, there won't be the congestion on the course, but I don't see how ... It's not clear how a separate starting line will help unless they are ... far apart and don't converge for some miles. ...
    (rec.running)
  • Re: what happens to reflected energy ?
    ... If the voltage is measured in volts and the current ...    transmission line. ... and reflected waves are as I provided above. ...
    (rec.radio.amateur.antenna)