Concepts and features
R&S
®
ZNA
248
User Manual 1178.6462.02 ─ 20
Defined coherence mode requires an analyzer with at least two independent internal
sources. It is compatible with arbitrary single-ended or balanced port configurations. It
can also be used for frequency conversion measurements.
The source ports and the properties of the coherent signals are all defined in the
"Source Coherence" dialog. After a system error correction, the coherent signals with
the selected properties are available at the calibrated reference plane.
Prerequisites for accurate phase control
●
Source coherence mode relies on wave correction. A consistent system error cor-
rection is essential for accurate coherent waves at the reference planes. You
should always perform a full n-port calibration (TOSM, UOSM or one of the Txx cal-
ibration types) of all physical ports involved and change the reference impedances,
if they differ from the default settings. A subsequent source power calibration is
recommended.
The system error correction applies to all a- and b-waves of the n calibrated ports,
not only to waves with a defined phase. You can also use offset parameters in
order to move the reference plane where the analyzer provides an accurate coher-
ent signal.
●
The defined phases are established during a pre measurement per sweep point
and source coherent port, which significantly slows down the sweep.
4.7.4.1
Amplitude Imbalance and Phase Imbalance Sweep
Since fimware version 2.40, amplitude and phase imbalance sweeps are no longer
limited to
, but are also available in source coherence mode.
In source coherence mode, during an amplitude or phase imbalance sweep, all source
signals are coherent.
●
During an amplitude imbalance sweep, the driving port operates at its port-specific
phase and performs a power sweep within a configurable, port-independent delta
range relative to its nominal port power.
●
During a phase imbalance sweep, the driving port operates at its port-specific
power and performs a phase sweep within a configurable delta range relative to its
port-specific phase.
Generator ports operate in CW mode, at their port-specific nominal power and phase.
4.7.5
True differential mode
Option R&S
ZNA-K61
Differential transmission lines and circuits are widely used, because their characteris-
tics give them a lower susceptibility to electromagnetic interference. Linear balanced
devices can be tested with sufficient accuracy using the
, where
the vector network analyzer generates unbalanced stimulus signals and uses a mathe-
matical transformation to convert unbalanced wave quantities into balanced S-parame-
Optional extensions and accessories
