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Validating a Calibration
Once a calibration has been performed, its performance should be checked before making
device measurements.
Why Validate a Calibration
There are several sources of error that can invalidate a calibration:
• bad cables
• dirty or worn connectors
• operator error
• measurement uncertainties from interpolation
Measure Known Standards
Measuring known devices, other than calibration standards, is a way of verifying that the
network analyzer system is operating properly. Verification kits use accurately known
standards with well-defined magnitude and phase response. These kits include precision
airlines, mismatch airlines, and precision fixed attenuators. Traceable measurement data
is shipped with each kit on disk and verification kits may be re-certified by Agilent. For
information about ordering verification kits, see
Perform ECal Confidence Check
ECal Confidence Check is a simple way to check the accuracy of a calibration (performed
with mechanical standards or an ECal module). The confidence check allows you to
measure an impedance state in the ECal module, called the confidence state, and compare
it with factory measured data (of the same confidence state). ECal Confidence Check
overlays the two traces so that the differences between the stored state and the measured
state can be easily viewed.
Before performing a confidence check, the analyzer must be calibrated and the calibration
type should be appropriate for the parameter being checked. For example, you cannot
measure the confidence state with S22 if an S11 1-port calibration is active.
NOTE
ECal Confidence Check is not available with ENA-L series network
analyzers.
For detailed information on performing an ECAl Confidence Check using a VNA, ENA or
PNA series network analyzer, refer to the appropriate user guide or online Help. To use the
internet to view the ENA or PNA online Help or an online VNA user guide, use the steps
listed in
"Finding More Information on Performing a Calibration" on page
Chapter 3
"Contacting Agilent" on page
Operating ECal Module
Validating a Calibration
1-15.
3-6.
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