Richard Harrison wrote:

If the transmitter is matched to the feedline to deliver maximum power,
no reflected power gets through the matching network. This means that
all reflected power is re-reflected by the network.

But then if there is no matching network, the reflected power must enter
the transmitter. Where does it go then? Is this what cooks the final?

This is demonstrative of the difficulties that arise when the loose
wording
promulgated by Bird, et al, is accepted literally. Not to mention the
difficulties that arise on lines with complex Z0.

Reasonable answers are only obtained once this view of reflected power
travelling back along the line is discarded. It is a voltage wave which
does the travelling.

Once this view of reflected power is discarded, you will be free to
study the implementation of your Bird and understand how it computes
the average of p(t) = v(t) * i(t) (the real definition of average
power on the line), by doing some additions and subtractions of v(t)
and i(t) and displaying it on an appropriate scale.

Unfortunately for clear understanding, the intermediate results of
this mathematical manipularion have been labelled Pfwd and Pref with
the result that many believe these actually exist.

I'd encourage anyone who doubts to do the derivation and show that
when you subtract the Pfwd and Pref displayed by your Bird that all
you have done is calculate Pnet = average(v(t) * i(t)) in a round
about fashion, so that of course it produces the right answer.
But this is no reason to ascribe physical meaning to Pfwd and Pref,
especially when it is clear that the whole notion collapses in the
general case of lines with complex Z0.

Rejecting the notion of Pfwd and Pref does not mean that your
Bird will stop being useful. When used to obtain a Pref of 0
it will be functioning perfectly fine as a TLI and when Pref
is not 0, you can still obtain Pnet by subtracting Pref from
Pfwd. But you will now understand how it really works and will
not be misled by false labels.

....Keith