Concepts and features
R&S
®
ZND
156
User Manual 1173.9557.02 ─ 61
must be well matched on both sides and cause an attenuation different from 0 dB; the
exact value of the transmission coefficient is not important.
As with TRL, TNA calibration is especially useful for planar DUTs. If TNA is not practi-
cable, TRL can be an alternative.
With a unidirectional R&S
ZND (see
on page 80) TNA calibration is not available.
4.5.1.11
Full n-Port calibration with reduced number of Through connections
The analyzer can calculate the error terms for a full n-port calibration after n−1 Through
measurements, if the measured Throughs connect all ports to be calibrated. The cor-
rection values for the unmeasured Throughs can then be calculated from the mea-
sured ones.
To establish a sufficient set of Through connections, you can select an arbitrary test
port as the "center" and measure all Through connections to this test port ("star-sha-
ped calibration"). You can also connect all ports in increasing order, e.g. 1→2, 2→3,
3→4 ...
[For the mathematically inclined: the graph constructed from the calibration ports as
nodes and the measured Throughs as edges must be connected.]
If an external switch matrix is configured and you want to calibrate three or more test
ports that are all on the
same submatrix
, then an extra Through measurement is
required: Complement the minimum set of n-1 Throughs (as explained above) by an
additional Through at a port pair that is connected by a "chain of throughs" of length 2
(e.g. between ports 2 and 4 in the examples above).
See
Chapter 4.7.20, "External switch matrices"
on page 220 for background informa-
tion on switch matrices and their submatrices.
Compared to the full number of n(n-1)/2 Through connections, the time and effort is
significantly reduced, in particular if n is large.
The "Reduced Through" logic is implemented for all full n-port calibration types.
●
During manual calibration, you can apply the calibration when a sufficient set of
Through connections have been measured. However, you can measure additional
Through connections to improve the accuracy.
●
a minimum number of port assignments. However, for each port assignment all
Calibration
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