Keysight N9938-90003 User’s Guide 105
Calibration for NA, CAT, and VVM Modes
Verifying Calibration and Jumper Cable Integrity
Verifying Calibration and Jumper Cable Integrity
After calibrating, it is important to verify that the calibration is good. When
using a jumper cable, also verify that the cable is of high quality.
Verify a Calibration
— Connect a LOAD standard at the calibration reference plane (where
calibration standards were connected). This may be at the end of the
jumper cable or at FieldFox PORT 1 connector.
—In CAT Mode, select Return Loss
.
—In NA Mode, select S11
with Log Mag format.
— For frequencies lower than 9 GHz, observe the trace on the FieldFox
screen:
— Lower than 35 dB indicates a GOOD calibration.
— Higher than 30 dB indicates that you should recalibrate.
Verifying Phase Accuracy
— Connect a LOAD standard at the calibration reference plane (where
calibration standards were connected).
— In NA Mode, select a S11 Reflection with Polar or Smith Chart format.
— Because all LOAD standards have delay, you should see a small amount of
phase rotation as a function of frequency. In general, the measurement
result should agree with the characteristics of the calibration standard.
Test the Jumper Cable
With the LOAD standard still connected, move the jumper cable while
observing the trace.
— If the measurement trace is relatively stable, the jumper cable is of good
quality.
— If you observe significant movement in the peaks of the measurement trace
when moving the cable (>5 dB), the jumper cable may need to be replaced.
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