On Tue, 20 Feb 2007 18:52:07 GMT, james wrote
in :

On Mon, 19 Feb 2007 22:52:40 -0800, Frank Gilliland
wrote:

+++Notwithstanding the fact that the non-reactive component of impedance
+++changes at or near resonance, maximum power transfer (due to matched
+++impedances) occurs regardless of whether those impedances are reactive
+++or not. Hence "impedance match" instead of the more limited "conjugate
+++match". As for your assertion that non-reactive impedances are rare in
+++the "real world", maybe you should describe -your- "real world" and
+++how it differs from the rest of reality.

**********
I am not saying that the real portion of impendances are rare. I am
saying that pure resistance is but a subset of complex impedance. Pure
resistance is where the reactive part of the complex impedance is
zero. In the real world no component has a "zero" reactive component
as does it not have zero resistive part.


Well, in my "real world" there are many components with reactances so
small as to be insignificant and are therefore ignored.


In conjugate matching, the nodal point where the output of the
transform network terminates with the load will have a net reactance
of zero. The real part is still there. It does not go away.


Okay....


The net
real part should be half that of the real part of the load.


Huh?


All components have complex impedances. In cases where frequency of
operation is well below the self resonance frequency, discrete passive
components can be thought of as purely resistive or purely reactive
dending on construction of the passive part. That be whether it is a
resistor or a capacitor or inductor.


Thank you. And I should add that it is more often the case where an
intended reactive component is measured for resistive impedance than
an intended resistive component is measured for reactive impedance.


Non passive components have
complex impedances.


Not necessarily, for the very same reasons mentioned above.


All the above is valid only when you are dealing with time varying
signals. Complex impedance has no definition when dealing with a non
time varying signal(ie. DC).


For all practical purposes, true.

But you are still ignoring the fact that a conjugate match is nothing
more than an impedance match using a conjugate impedance, which is
often not necessary. Just because some comp resistors -- or even the
wires or PCB traces -- in an audio amp or power supply may have a very
slight inductive reactance doesn't mean you waste your time trying to
load them all with sub-pF caps. That's why, here in the real world,
the term "impedance match" is used to include any necessary conjugate
match that may (or may not) be necessary, and why you don't hear the
term "resistance match" used very often (i.e, never).