On 1/23/13 6:48 AM, David Kirkby wrote:
There's a fairly interesting (to me at least), discussion on an
Agilent forum devoted to the calibration of vector network analyzers.
http://www.home.agilent.com/owc_discussions/thread.jspa?threadID=34809&tstart=0
The title of the thread is "Coefficients of fringing capacitance polynomial"
A student needs to find the open-circuit fringing capacitance of a
piece of microstrip line. For this he needs to know the time between
the reference plane of the SMA connector and the open circuit
microstrip.
Can he build multiple microstrips with known distances, and measure them
all and solve for it that way?
An obvious way to do this is with a vector network analyzer with a
time-domain option. In HP/Agilent VNAs, this is option 010. The
student has access to an obsolete and unsuported HP 8753C 6 GHz VNA,
but it does not have the time-domain option.
Does it have the "measurement plane offset" option? I'm not in front of
my old analyzer in the lab (8720C.. no disk drive), and it does have the
transform option, but I'm not sure you need that option to have the
"dial an offset" in the calibration. I've used that to move the
reference plane from the connectors at the edge of a board to the device
on the board: testing a vector modulator with the display in polar
coordinate mode, for instance.. you keep turning the knob til the
display is a dot, not a circle or arc.
I thought he might be able to convince someone at Agilent to give the
uni this option, which is just enabled by software. So far that has
not worked. I did offer to help with access to my HP 8720D VNA which
has the time-domain option.
What measurement uncertainty is called for here? Can you make your own
limited purpose cal kit? The open is the challenge. Shorts, loads, and
thrus are fairly straightforward. Maybe you have to collect the
uncalibrated data with the cal standards and do the "cal" in post
processing in Matlab or something.
_______________________________________________
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
