On 26 mayo, 11:09, Cecil Moore wrote:
On May 26, 6:59*am, Cecil Moore wrote:

That knowledge can be obtained
from any good optics reference book including "Optics", by Hecht and
"Principles of Optics", by Brown and Wolf.

Continuing after taking my wife to work:

The reason that optical physicists know so much more about energy
transfer than RF gurus is that the optical physicists do not have the
luxury of measuring the voltage and current associated with an EM wave
at light frequencies. They have historically been forced to deal with
irradiance, i.e. power density, at every step of their analysis since
that is the only thing they could easily quantize through
measurements. As a result, they know everything one needs to know
about where the energy goes during reflection and wave cancellation.
If one wants to catch up on such as it applies to all EM waves,
including RF waves, please obtain a copy of "Optics", by Hecht and
read the chapters on superposition and interference. It was an eye
opener for me and resulted in my WorldRadio energy analysis article.

http://www.w5dxp.com/energy.htm

Optical physicists usually make power density (irradiance)
measurements and then calculate the electric and magnetic fields of
the EM wave. RF gurus make voltage and current measurements and ignore
energy/power except for net power in and net power out thus losing
important details in the process. When they don't understand energy
transfer, they dismiss it as unimportant or worse yet, assume that
their ignorance somehow proves something as W7EL has done in his "food
for thought" article on forward and reflected power. All that he has
succeeded in proving is his ignorance of partial or total wave
cancellation involving two superposed component waves which can
reverse the flow of energy in a transmission line just as easily as
can an actual reflection. Here is a diagram of the energy flow at a 50-
ohm Z0-match as is common in ham installations.

http://www.w5dxp.com/enfig3.gif

Pref1 = Zero = P3 + P4 - 2*SQRT(P3*P4)

where P3=P4 and the two electric fields are 180 degrees out of phase.
This is total destructive interference due to wave cancellation, i.e.
out-of-phase superposition.

Pfor2 = P1 + P2 + 2*SQRT(P1*P2)

This total constructive interference due to in-phase superposition.

If W7EL would use the general power density equation on his "food-for-
thought" examples

Ptot = P1 + P2 + 2*SQRT(P1*P2)cos(theta)

he would obtain all the correct answers as to where the reflected
energy goes, i.e. the energy analysis would agree exactly with his
voltage analysis. That energy analysis would tell us exactly how much
reflected power is absorbed in the source resistor and exactly how
much is redistributed back toward the load as part of the forward
wave. But when W7EL heard these facts of physics from the field of EM
wave optics many years ago, he said "Gobbleygook".
--
73, Cecil, w5dxp.com

Hi Cecil

Continuing after taking my wife to work:

Yo have a chopper, I have a chopper. Your wife go to work, my wife go
to work. Are you my big brother? (older brother? = "hermano mayor",
in spanish) :D
....
Dr. Corum tells us what the problem is: "Lumped circuit theory fails
because it's a *theory* whose presuppositions are inadequate.

Well... "theories" are theories, models of "reality". As Einstein
said: "free creations of the human mind" = Newton's gravity theory,
Einstein's gravity theory...
Einstein one of course it is more accurate in certain situations, but
we still using Newton's laws to send spacecrafts to Mars. As in the
Sears-Zemansky example given, they coexist and it can solve differents
problems.
Velocity adding fails at very high speeds ("presuppositions are
inadequate") and we need relativity, but for common situations it is
not necessary use the last one (of course you know it, it is only a
note). It is easy for us become tempted to think that Einstein one it
is the "true" theory and not "a better aproximation to reality"
theory.

As some of us agree "all models are false", then, perhaps --only
"perhaps"-- (I do not want offend to anyone) some of the others models
presented by our distinguished colleages could not be as precise for
certain special situations, but still quite adequate to solve problems
or explain more simple things, as a Newton laws or "charges in
movement"...

As in other physics laws, it is not possible to reach a similar
consensus here in this regard? Models given, leads to wrong numbers or
failed to agree with empiric data?

Your examples, Cecil, gve me a light, now I have in my mind three
models that (for me) describe "reality" so good. With yours I can
think in forward and reflected power flowing simultaneously on Rs -not
contradiction-
Adding phasors of the forward and reflected travelling waves before
the last one reach generator, this one sees different Z line input and
not any reflected power there is circulating on it (not contradiction
to me) = "adding" in my human mind, of course. Reality only God/Allah/
Yahweh/Manitou/The Force/Zeus, knows- :) .

I'm not trying to be syncretic. Same cat, different models... Is it
not possible that?

73

Miguel Ghezzi LU6ETJ