Agilent Technologies N4413A User Manual page 74

Using the Multiport Test System
How to Characterize Balanced Devices
The mixed-mode S-parameters of the asymmetrical device are shown below:
The phase skew can have a significant effect on the performance of a balanced device as
shown in the mixed-mode S-parameter. The most noticeable change is in the mode conversion
parameters, designated by the SDCnn and SCDnn terms. In a perfectly symmetrical device,
these terms are equal to zero. Even a slight asymmetry is more noticeable in these terms than
in the pure-mode terms (SDDnn or SCCnn).
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