On Sun, 27 Oct 2019 at 19:15, <erik@...> wrote:
Well, the delays did not work as expected.
So I'l formulate my tuning question a bit more to the point.
The green line in attached picture shows the outcome of this formula
"phase(S11open) - phase(S11short) - pi" of a 1 meter coax cable versus the
frequency (0.5 till 900MHz)
The phase is unwrapped to avoid discontinuities.
The line should be flat on 0 independent of the frequency but it is not. 0
means the S11open and S11short are exactly opposite on the smith chart
Why should phase of S11 open and S11 short be 180 degrees apart?
Are just leaving open a bit of coax, then adding a short to it? If so, the
phase difference will not be 180 degrees due to the fringing capacitance of
the cable. That phase difference will increase with frequency. That's well
all well-engineered calibration kits have the offset delay on the short a
bit longer than on the open.
Dave
