Ian White GM3SEK wrote:
I share Tom B's suspicions. Since Cecil's analysis is leading to
physical absurdities such as "watts of destructive interference" and
vagueries such as "elsewhere in the system", it means that something is
wrong.

Do you think Eugene Hecht of "Optics" fame is wrong?
The unit of irradiance is "watts per unit area" and is
NOT a "physical absurdity". Hecht uses "watts per unit
area of destructive interference" quite often in his
classic textbook. He says the spacial average of all
interference must be zero so that the watts per unit
area of constructive interference must be balanced by
the watts per unit area of destructive interference
elsewhere in order to satisfy the conservation of
energy principle.

Nothing is wrong, Ian, you are simply ignorant. I suggest
you read the chapter on interference in "Optics" and try
to comprehend it. It might do you good to learn something new.

Either way, it is Cecil's tarbaby, and nobody else needs to get stuck to
it.

By all means don't try to learn and understand anything new.
Newsgroup gurus apparently already know all there is to know
and are therefore incapable of additional learning.

The rest of us can continue to use the methods that have existed for a
hundred years to account for the voltages, currents and phases at any
location along a transmission line, and at any moment in time.

And that is exactly why you don't understand reflected energy.
An understanding of of interference can be had from a voltage
analysis but you obviously have never performed such. It is
common knowledge that V1^2+V2^2 is not equal to (V1+V2)^2.
The question as to why they are not equal has been avoided
even though it is easy to answer. If (V1+V2)^2 V1^2+V2^2
then the superposition of voltages has resulted in constructive
interference. If (V1+V2)^2 V1^2+V2^2 then the superposition
of voltages has resulted in destructive interference. Away
from any source, constructive interference must always equal
destructive interference to avoid violating the conservation
of energy principle. At a Z0-match point, the reflected energy
is redistributed back toward the load by constructive interference.
An equal magnitude of destructive interference occurs toward
the source thus eliminating reflected energy toward the source.
It is the same way that thin-film non-reflective glass works.
--
73, Cecil http://www.w5dxp.com