Frequency Drift; Performance Verification; Reference Plane And Port Extensions - Agilent Technologies 8719D User Manual

Minute changes in frequency accuracy and stability can occur as a result of temperature and
aging (on the order of parts per million).
Override the internal crystal with a high-stability external source, frequency standard, or (if
n
your analyzer is equipped with option lD5) use the internal frequency standard.
You should periodically check the accuracy of the analyzer measurements, by doing the
following:
Perform a measurement verification at least once per year
n
Refer to the HP 8?'19D/2OD/22D Network Anulgm seruice Guide for the measurement
verification procedure.
Use the port extension feature to compensate for the phase shift of an extended measurement
reference plane, due to such additions as cables, adapters, and Gxtures, after completing an
error-correction procedure (or when there is no active correction).
Using port extensions is similar to using electrical delay. However, using port extensions is the
preferred method of compensating for test fixture phase shift. 'Iable 5-1 explains the difference
between port extensions and electrical delay.
Differences between PORT EXTENSIONS and ELECTRICAL DELAY
The end of a cable becomes the test port plane Compensates for the electrical length of a
Main Effect
for all S-parameter measurements.
All S-parameters.
Intelligently compensates for 1 times or 2
Electrical
times the cable's electrical delay, depending
on which S-parameter is computed.
Then enter the delay to the reference plane.
. . . A i . . . . . . . . . . . / . . . . . . . . . . . . . . : . . . . . : : : . . : : .. . . . . . . . . i : : : . . . . i . . . . < i..... <m. : . . .
cable.
Set the cable's electrical length x 1 for
transmission.
Set the cable's electrical length x 2 for
reflection
Only the currently selected S-parameter.
Only compensates for electrical length.
Optimizing Measurement Results 63