HP HP 8712ET, User Manual, Page: 223 / 480

ET User’s Guide 5-17
Optimizing Measurements
Compensating for Phase Shift in Measurement Setups
Compensating for Phase Shift in
Measurement Setups
Port Extensions
The port extension feature is used to compensate for the phase shift
caused by the insertion of cables, adapters, and fixtures into the
measurement path.
Port extension is particularly useful if you are unable to perform a
calibration directly at your DUT. (See
Figure 5-2, “Compensating for Test
Fixture Delay,” for this discussion.) For example, you might have a test
fixture with type-N connectors, where you can easily perform an accurate
calibration. However, calibrating at this connector does not remove the
electrical length within the fixture. The desired calibration reference
plane is on the other side of the test fixture where you may have device
specific connectors. Port extension lets you compensate for this delay
within your fixture by removing the phase shift that it causes.
Figure 5-2 Compensating for Test Fixture Delay