On Fri, 12 Mar 2004 03:51:35 GMT, Gene Fuller wrote:

Cecil,

OK, I will 'see' your references and 'raise' my bid to Born and Wolf
"Principles of Optics", 7th edition.

I recommend section 1.6, "Wave propagation in a stratified medium.
Theory of dielectric films". This section runs from page 54 to page 74,
and it describes in full detail everything you would want to know about
propagation of waves in multilayered structures.

There is a disclaimer in the introduction to this section which says,
"For the treatment of problems involving only a small number of films it
is naturally not necessary to use the general theory, and accordingly we
shall later describe an alternative and older method based on the
concept of multiple reflections." The reference is to section 7.6
"Multiple-beam interference", which runs from page 359 to page 409.

Well, Gene, you apparently deny that 'bouncing' waves exist. So what exactly are
'multiple reflections'?

Similar sections are included in the 6th edition of this book, on pages
51 to 70 and 323 to 367 respectively. I am sure you can find one or both
of these editions in the TAMU library. I prefer the 7th edition, as it
seems easier on the eyes.

If you choose not to actually read these references I will tell you that
the first section is a full-blown Maxwell's equations treatment, and the
second section employs an interfering wave treatment.

So I now ask, if your selected reference discusses interfering wave treatment
and multiple reflections in the explanation of impedance matching, then why do
you consider Cecil's position concerning reflected energy joining the forward
wave as purely in his imagination? Seems as if you're wearing opaque glasses
backward.

What I find interesting is that there is not one mention of bouncing
energy waves or waves that have disappeared but their energy lives on.
If you read your favorite Melles-Griot material carefully without adding
your own spin (how else could it be, etc.) you will see that they do not
discuss bouncing energy waves either. You will notice that M-G say the
energy "appears" in the transmitted wave. This is good, since we like to
believe conservation of energy is maintained. M-G do not discuss the
mechanism. All of the stuff about bouncing energy rejoining the forward
wave is purely in your imagination.

Imagination, indeed!

I think I have finally figured out the root of the disagreement. Your
approach is similar to a one-trick pony. You have latched onto the
concept of interference to the exclusion of any other valid approach. As
a consequence it becomes *necessary* to imagine such things as bouncing
energy waves. The Maxwell's equations approach does not require this
sort of crutch. Try it, you might like it.

Gene, multiple reflections in wave mechanics are the basic tools that accomplish
impedance matching--no way are the reflected waves any sort of a crutch. There
can be NO matching of different impedances without reflections. How could there
not be reflections when electromagnetic waves encounter a diffferent impedance
when going from medium to another?

I am quite familiar with both analytical methods, and I am comfortable
in using either one. The key is understanding when a given analytical
technique will be the most useful, most direct, most intuitive, and so
on. I have nothing against interference, but its misapplication is like
using a pipe wrench to drive a nail while a hammer is right at hand.

Wave interference is the total basis for all impedance-matching operations.
There is no misapplication of wave interference, and your assertion that the
pipe wrench and hammer apply here is absurd.

If you have a copy of QEX for Mar/Apr 1998 please review an article there
concerning this subject. It just might give you the opportunity of looking at
the concept from a somewhat different perspective.

Walt, W2DU