wrote in message
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How close Z11=((1+s11)*(1-s22)+s12*s21)/((1-s11)
*(1-s22)-s12*s21) will be to the stated large signal
impedances after you convert
it to a series equivalent impedance on the Smith
chart, I don't really know.

Note:

In the above formula Z11 should be replaced by
Z11 / Z0. In other words Z11 is "normalized" with respect to Z0 in this
formula. See the Gonzalez reference.

In a "normalized" Smith chart Z0=1.0.

Bill W0IYH

William E. Sabin wrote:
wrote in message
oups.com...

How close Z11=((1+s11)*(1-s22)+s12*s21)/((1-s11)
*(1-s22)-s12*s21) will be to the stated large signal
impedances after you convert
it to a series equivalent impedance on the Smith
chart, I don't really know.

Note:

In the above formula Z11 should be replaced by
Z11 / Z0. In other words Z11 is "normalized" with respect to Z0 in
this
formula. See the Gonzalez reference.

In a "normalized" Smith chart Z0=1.0.

Bill W0IYH


You're correct according to Pozar.

I'm gonna assume that this was just a
typo on Gottlieb's part (pg.131, Practical
RF power Design Tech.), and what he really
meant to type was lowercase "z11", to show
it was normalized. (I have a feeling Gottlieb
just copied this out of another book, just like
i copied it from him! heheh...)

But you bring up a good point:
I might be barking up the wrong tree here if
Z11 or z11 is defined as the input impedance
when port 2 is open circuited.
This shouldn't be the same as the large
signal input impedance, when the output is
approximately conjugately matched.



Slick

Note:

In the above formula Z11 should be replaced by
Z11 / Z0. In other words Z11 is "normalized" with respect to Z0 in
this
formula. See the Gonzalez reference.

In a "normalized" Smith chart Z0=1.0.

Bill W0IYH

If the output is terminated with a 50 ohm pure resistance load then S11 is
the complex input reflection coefficient, 0 to 1.0. In an active circuit
(amplifier or oscillator) S11 can be outside these limits due to positive
internal DUT feedback.

Bill W0IYH