R&S ZNB Series User Manual page 198

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R&S ZNB/ZNBT
A lower label in the list has priority over the higher labels (e.g. if the power calibration is
interpolated and the source power is changed, then the label PCao is displayed).
Interpolation and extrapolation
The analyzer can interpolate and extrapolate power correction data so that a source or
receiver power calibration can be reused after a change of the frequency sweep range:
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At new sweep points within the calibrated sweep range, interpolation is applied to
calculate the correction data. A label "PCai" in the trace list indicates an interpola-
ted power calibration.
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At new sweep points outside the calibrated sweep range, the correction values are
extrapolated: Sweep points below the lowest calibrated frequency are assigned the
correction value of the lowest frequency. Sweep points above the highest calibra-
ted frequency are assigned the correction value of the highest frequency. A label
"PCax" in the trace list indicates an extrapolated power calibration.
4.5.6.4 Extended test setups
The power calibration data can be modified to account for an additional two-port device
in the test setup. The known transmission coefficients of the two-port can be entered
manually or automatically (Channel – [Cal] > "Pwr Cal Settings" > "Transm. Coeffi-
cients..."). The R&S ZNB/ZNBT supports two different test scenarios.
A: Two-port at DUT (during measurement)
Test and measurement procedure:
1. Perform the calibration without the additional two-port. During the calibration, the
analyzer decreases the power sensor values by the 2-port transmission coefficients
to move the calibration plane of the power calibration towards the input of the DUT.
The calibration plane corresponds to the output of the 2-port which is placed in-
between the network analyzer port and the DUT.
2. Perform the measurement with the additional two-port.
Practical example: On-wafer measurements. The power sensor cannot be directly
connected to the input of the DUT. The transmission coefficients of the wafer probe are
used for the power meter correction.
User Manual 1173.9163.02 ─ 62
Concepts and features
Calibration
198