On Tue, 29 Oct 2019 at 20:11, <erik@...> wrote:
The vertical scale is the abs of the measured s11. Zero to one. Red an
green lines
The pink line is S11 open phase minus S11 short phase minus pi.
What would the offset delay do to the rotation of S11 open and short.
Would it impact the phase or also the magnitude.
Would it be constant shift or frequency dependent?
Hi,
I need to go out, so don't have time to re-arrange all these equations into
the form you want, but hopefully it will get you started.
A section of transmission line with a vacuum dielectric causes a phase
shift phi of
phi = 2*Pi*L/lambda
where lambda is the wavelength (metres), and L the length (metres).
The wavelength lambda = c/f where f is the frequency in Hz, and c the
velocity of light in a vacuum.
so phi = 2*Pi*L*f/c
*So the phase shift is directly proportional to frequency, and directly
proportional to the length of the line. *
Some manufacturers of cal kits use a length (e.g. Rohde and Schwarz), and
others a delay (e.g. Keysight). They are related by the velocity of light
in *vacuum*, not air or the dielectric. That's the convention used - it is
obviously not realistic in practice.
The delay d (seconds) of that transmission line lf length L is L/c, where c
is the velocity of light in vacuum.
e.g. 30 ps is 8.9938 mm.
So the phase shift phi is proportional to frequency, and proportional to
the delay. Obviously you get phase wrapping too, but that's another issue.
If those don't make any sense, I would have screwed up somewhere.
--
Dr David Kirkby Ph.D C.Eng MIET
Kirkby Microwave Ltd
Registered office: Stokes Hall Lodge, Burnham Rd, Althorne, CHELMSFORD,
Essex, CM3 6DT, United Kingdom.
Registered in England and Wales as company number 08914892
Tel 01621-680100 / +44 1621-680100
