Concepts and features
R&S
®
ZNB/ZNBT
191
User Manual 1173.9163.02 ─ 62
For a channel with more calibrated ports than cal unit ports available, you can change
the port assignments and rerun the automated validation. Or you can switch to
advanced mode and validate each port manually.
Advanced mode
In advanced mode you can configure the validation settings (reference characteriza-
tion, deviation limits) and run or rerun particular measurements (reflection at port p with
connected Open, Short or Match).
4.5.5.6
Multiple port assignments
With multiple port assignments, you can calibrate port groups of any size, no matter
how many ports your calibration unit (or cal unit characterization) has. For example,
you can use a 2-port calibration unit to perform a full 4-port calibration.
The multiple port assignment method considerably extends the range of applications of
the calibration units. However, the method entails some loss of convenience because
you have to reconnect the calibration unit between the different calibration stages
(assignments). It can also cause a loss of accuracy because only a subset of all possi-
ble through connections is measured.
To calibrate n test ports with an m-port calibration unit (m<n), the calibration unit has to
be connected at least n/m times. Each connection is described by its "port assign-
ment", i.e. the mapping of calibration unit ports to test ports. Then for each assignment
an automatic calibration is performed. Finally the analyzer combines the calibration
data and calculates the required n-port error terms.
This calculation is possible if and only if:
●
The port assignments "cover" the calibrated test ports
●
The overlap between assignments allows a(n ordered) "chain of measured through
connections" between any (ordered) pair of test ports requiring a Through mea-
surement
For full n-port calibrations, to calculate the correction terms for those test port pairs that
are not covered by a single assignment, the R&S
ZNB/ZNBT applies the "reduced
through" logic. See
Chapter 4.5.1.11, "Full n-Port calibration with reduced number of
Calibration
