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Old January 29th 07, 07:17 PM posted to rec.radio.amateur.antenna
K7ITM K7ITM is offline
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First recorded activity by RadioBanter: Jul 2006
Posts: 644
Default Thevenin and s-parameters...



On Jan 29, 2:12 am, "camelot" wrote:
Thank you for your comments,
I'm doing some calculations and simulations in order to verify if I
can bypass representation problem of s-parameters in other ways rather
than the Thevenin one.
There is one thing I'd like to submit to your attention, the known
formula
S11=(Zin-Z0)/(Zin+Z0),
where Z0 is the port impedance and Zin the load, does not works if you
consider Z0 not pure real (usually 50 ohm) but composed by a real and
an imaginary part i.e. Z0 = a+jb.
Are there other known formulas for S11 for Z0 real+imaginary?

Camelot


Frank has already provided you with links to (I presume)
transformations to other linear two-port representations.

But I'm curious. Why do you think that the formula you wrote above
doesn't work when Z0 is complex? In what way do you think it does not
work?

I'm also curious why you would pick a complex reference impedance for
S-parameter work, but that's really a different issue.

Cheers,
Tom