On Feb 19, 11:07 am, Keith Dysart wrote:
....
As well, what would be the equivalent expression for the following
example?

+-------+-------------+----------------------+
| | |
^ | Rs |
Is +-/\/\/-+ 1/2 wavelength ZLoad
2.828A 50 ohm | 50 ohm line |
| | |
+---------------+-----+----------------------+

The forward power is the same, the source impedance is the same,
but the conditions which cause maximum dissipation in the source
resistor are completely different.

Which, of course, illustrates the point that I believe Roy made in the
article, that the load conditions (whether they are the result of
something going on involving a transmission line, or just a lumped
load) tell us nothing about what's going on inside a source, ideal or
otherwise. For that, you MUST know the characteristics of the source
itself, and for that you do NOT need to know anything about the load
beyond the impedance it presents to the generator output terminals
(possibly as a function of time, frequency, amplitude and other
factors). For example, in the case of the signal generator on my
bench when 100dB of attenuation is cranked in, the change in
dissipation inside the generator versus load impedance is
inconsequential: at least 99.999 percent of the generator's available
RF output is dissipated in the attenuator when the load is matched (50
ohms). The additional maximum possible 0.001 percent increase
depending on load would be difficult to detect: about 0.00004dB
change. On the other hand, the change in dissipation inside my 450MHz
transmitter versus load impedance is substantial, BUT bears no
resemblance to either the current-source-with-shunt-resistor or the
voltage-source-with-series-resistor model, for multiple reasons.

Cheers,
Tom