Reducing Mismatch Errors; Reducing Mismatch Errors In A Reflection Measurement - HP 8712ET User Manual

Optimizing Measurements

Reducing Mismatch Errors

Reducing Mismatch Errors
Mismatch errors are due to the fact that the analyzer's port impedances
are not exactly 50 ohms or 75 ohms across the frequency range.Source
match errors are produced on the source (analyzer RF OUT) side of the
DUT; load match errors on the load (analyzer RF IN) side. If the DUT is
not connected directly to the port, the mismatch errors due to cables,
adapters, etc. are considered part of the source or load match errors.
Source match and load match error terms can be reduced by using the
methods described in this section.
Reducing Mismatch Errors in a Reflection
Measurement
The best way to reduce mismatch errors in a reflection measurement of a
two-port device is to perform a reflection calibration directly at the point
that will connect to the DUT, using the exact frequency parameters that
you will be using for the measurement. The accuracy of a one-port
calibration for a two-port device can be increased dramatically by
terminating the output port of the device with a high quality Z
0
termination (a load from a calibration kit, for example) instead of
connecting it to the analyzer.
1. Set up your reflection measurement and frequency parameters.
2. Press CAL 1-Port .
3. Follow the instructions on the display.
See Chapter 6 for more information on calibration choices for reflection
measurements.
ET User's Guide 5-15