R&S ZVB - Page 384

R&S
®
ZVA / R&S
®
ZVB / R&S
®
ZVT GUI Reference
Channel Menu
Operating Manual 1145.1084.12 – 30 369
In general, it is recommended to calibrate all frequency ranges in all noise figure calibration stages at once
to obtain a sufficient set of calibration data (click the higher-level node Port <n> RF... etc.).
3. Receiver Power Calibration gives access to the Scalar Mixer Measurement Power Calibration dialog for
the previously selected DUT output port. If a preamplifier is connected between the DUT and the receive
port of the analyzer, or if the output signal of the DUT is fed to the MEAS IN connector of option R&S
ZVA<frequency>-B16, Direct Generator and Receiver Access, in order to bypass the coupler and improve
the receiver noise figure, the check box should be selected. This activates the input fields for the base
power and source step attenuator settings (if available), which you may have to adjust to the test setup in
the receiver path in order to avoid excess receiver input power levels (receiver compression; see data
sheet). It also activates the Port <n> Pwr Offset field in the S-Parameter Calibration panel. An active
check box has no additional effects.
The base power setting overwrites the Channel – Power Bandwidth Average – Power setting after you
confirm the Reduce IF bandwidth... message box in order to open the calibration dialog. The step
attenuator setting immediately overwrites the source attenuator settings for the DUT input port in the
Channel – Power Bandwidth Average – Step Attenuators dialog.
4. Define Noise Figure opens the Define Noise Figure Measurement dialog, providing basic settings for
the noise figure measurement.
5. Noise Figure Calibration opens the Noise Figure Calibration dialog to assess and compensate the
internal noise at the NWA receiver and source.
6. S-Parameter Calibration opens the Calibration wizard for the previously selected input and output ports
and the Cal Method. If this step is skipped, the previous power and noise figure calibrations effectively
ensure a transmission normalization; the noise figure trace line contains no calibration state label (except
Pcal or another power calibration state label). With an additional S-Parameter Calibration (i.e., a Full One
Port calibration at the RF and IF ports), the system error correction of the gain G
D
(and thus the noise
figure measurement in total) is improved; the trace lines for the calibrated ports indicate Cal; the noise
figure trace is labeled Cal NCal (see Noise Figure Calibration State Labels). The S-Parameter Calibration
is a prerequisite for an Enhanced Wave Correction at the RF and IF ports.
Port <n> Pwr Offset is enabled if Preamp or Direct Receiver Access Used is checked in the Receiver
Power Calibration panel. <n> is the DUT output port number. The power offset increases or decreases the
source power at port <n> during the calibration. If a generator step attenuator is available at port <n>, it
also selects the Low Noise step attenuator mode. If a pre-amplifier is used in the receiver path, a power
reduction (negative value of the Port <n> Pwr Offset) may be required to prevent excess power levels at
the input of the pre-amplifier or at the NWA receiver port during the calibration.
Note: An S-parameter calibration is required for S-parameter measurements in parallel to the noise figure
measurement. The large IF bandwidth required for noise figure measurements limits the accuracy of the
calibration and the subsequent S-parameter measurements. In general, the AVG detector largely
improves the results.
7. Configure Traces provides a selection of traces which are commonly of interest for the noise figure
measurement. The selected traces are created and displayed when the Replace or Add buttons are
clicked. Moreover, the DUT input port (e.g. P 1) appears in front of the power values in the channel line
The noise figure trace (NF21) is smoothed automatically (label SMO in the trace line). The large IF
bandwidth limits the accuracy of the S-parameter measurement; the AVG detector can improve the
results. Use the Trace – Measure menu if you wish to modify the trace settings.
To avoid misleading results, S-parameter selection is enabled only after an S-Parameter Calibration has
been performed.