On Jun 17, 12:38*am, Owen Duffy wrote:
The notion that reflected power is simply and always absorbed in the real
source resistance is quite wrong. Sure you can build special cases where
that might happen, but there is more to it. Thinking of the reflected
wave as 'reflected power' leads to some of the misconception.

Again, exactly who proposed that notion? The "power" in a reflected
wave is actually reflected energy measured at some point on the
transmission line. Reflected EM waves cannot exist without ExH energy
per unit time per unit area.

The special case where 100% of the reflected power incident from a
Z0=50 ohm transmission line is dissipated in the 50 ohm source
resistor happens when there is zero interference between the forward
wave and reflected wave. Since it is not true when interference
exists, it is logical to conclude that interference has something to
do with the reflected power results deviating from the zero
interference case - and so it does. The interference term in the power
density equation indicates what kind of interference exists and what
happens to the interference energy.

Roy's experiment was designed to eliminate re-reflections from the
source and it does exactly that. What that means is that all of the
variations in power distribution are associated with interference, the
other mechanism by which RF wave energy can be redistributed. Contrary
to w7el's assumption, EM wave reflection is NOT the only mechanism for
redistributing RF energy in a transmission line. That glaring fact of
physics is what most of the RF experts are missing.
--
73, Cecil, w5dxp.com