R&S ZNA50 - Page 90

Concepts and features
R&S
®
ZNA
90User Manual 1178.6462.02 ─ 20
Parallel Measurements with Frequency Offset
When performing parallel measurements, it is possible to specify a minimum frequency
offset between the port groups. This is particularly useful for situations where "Cross-
talk" between different DUTs would otherwise make the simultaneous measurement
impossible (e.g. in wafer prober applications).
Example:
Consider a linear frequency sweep with 101 points from 100 MHz to 200 MHz resulting
in a frequency step size of 1 MHz. When two port groups are defined and a minimum
frequency offset of 1 MHz is specified, a parallel measurement with frequency offset is
performed internally as follows:
●
In the first measurement step, no measurements for port group 1 will be performed;
measurements for port group 2 will be performed at 100 MHz.
●
In the second measurement step measurements for port group 1 will be performed
at 100 MHz; measurements for port group 2 will be performed at 101 MHz.
●
In the third measurement step measurements for port group 1 will be performed at
101 MHz; measurements for port group 2 will be performed at 102 MHz.
●
…
●
In the 101st measurement step measurements for port group 1 will be performed at
199 MHz; measurements for port group 2 will be performed at 200 MHz.
●
Finally, in the 102nd measurement step measurements for port group 1 will be per-
formed at 200 MHz; no measurements for port group 2 will be performed.
Parallel measurement with frequency offset is transparent to the user: All port groups
will be measured in the requested frequency range. The results are available in the
same form as if they were obtained in separate measurements without frequency off-
set.
Please note that in parallel measurement with frequency offset the firmware uses a
modified IF as compared to measurements not using this mode. Because this modified
IF requires a special calibration, it is essential to perform the Calibration with the same
Frequency Offset settings as for the actual measurement; otherwise the calibration is
turned off (see "Cal Off label" on page 160).
4.1.4.3 Stimulus and sweep types
The function of the Stimulus keys [Start], [Stop], [Center] and [Span] depends on the
sweep type.
Table 4-1: Function of Stimulus keys
Sweep type [Start](unit) [Stop] (unit) [Center] (unit) [Span] (unit)
"Lin Freq" "Start Frequency" (Hz) "Stop Frequency" (Hz) "Center Frequency"
(Hz)
"Span Frequency" (Hz)
"Log Freq" "Start Frequency" (Hz) "Stop Frequency" (Hz) – –
"Segmented" – – – –
Basic concepts