Concepts and Features
R&S
®
ZNB/ZNBT
151
User Manual 1173.9163.02 ─ 38
Compared to the full number of n(n-1)/2 Through connections this is a significant
reduction in time and effort, 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 as soon as a sufficient set
of Through connections have been measured. However, you can measure addi-
tional Through connections in order to improve the accuracy.
●
always proposes a minimum number of Through connec-
tions, which is particularly helpful if
are used.
In case an External Switch Matrix is used and three or more test ports shall be calibra-
ted that are all located on the
same submatrix
, an extra Through is required: comple-
ment 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 226 for background informa-
tion on switch matrices and their submatrices.
4.5.1.12
Complementary Isolation Measurement
For each port pair in a manual transmission normalization or TOSM calibration, the
Through measurement can be complemented by an isolation measurement, account-
ing for possible crosstalk between the related test ports (e.g. on a test fixture).
If isolation is measured, the corrected transmission coefficient of the DUT is calculated
as
(Transmission coefficient DUT – Isolation) / (Transmission coefficient Through – Isola-
tion)
There is no dedicated physical standard for isolation measurement; it is recommended
to suitably terminate the test ports (e.g. with 50 Ω loads).
4.5.2 Calibration Standards and Calibration Kits
A calibration kit is a set of physical calibration standards for a particular connector type.
The magnitude and phase response of the calibration standards (i.e. their S-parame-
ters) must be known or predictable within a given frequency range.
The standards are grouped into several types (Open, Through, Match,...) correspond-
ing to the different input quantities for the analyzer's error models. The standard type
also determines the equivalent circuit model used to describe its properties. The circuit
model depends on several parameters that are stored in the cal kit file associated with
the calibration kit.
Calibration
