On Sun, 27 Oct 2019 at 16:02, <erik@...> wrote:
Doing a manual optimization using
openC0=300e-15 F
openC1=-250e-24 F
did result in an reduction of the amplitude variations (blue lines, see
attached picture)
Changing shortL0 seemed to have a similar impact as openC0 so I do not
know how to reduce both amplitude and phase variations (red lines)
Someone else (forget who), showed to my satisfaction at least, that there
was no need for anything beyond C0 for cal kits. He checked 3 kits I own
* 85054B 18 GHz N
* 85052B 26.5 GHz 3.5 mm
* 85050B 18 GHz APC7.
He used some Octave code which showed that for those cal kits at least,
there was no point having any more than C0, as the effects of C1, C2 and C3
are smaller than the uncertainties of the calibration kits.
Your value of 300 fF for C0 seems large. I would expect that to be below
100 fF for almost any kit.
I suspect you are ignoring the offset length, and trying to do it all with
a capacitance, which will not work.
Dave
