Concepts and Features
R&S
®
ZNB/ZNBT
121User Manual 1173.9163.02 ─ 53
The extension of the impedances to more ports and mixed mode measurements is
analogous to S-parameters. Z
dd44
is the differential mode input impedance at port 4 of a
DUT that is terminated at its other ports with the reference impedance Z
0
.
The Converted Admittances are defined as the inverse of the converted impedances.
Reflection Impedance
The converted impedance Z
ii
(1 ≤ i ≤n) describes the input impedance at port i of the
DUT.
U
0
I
1
U
1
Z
0i
Z
ii
Example:
For a 2-port DUT that is terminated at its output with the reference impedance Z
02
, Z
11
is the input impedance (matched-circuit impedance measured in a forward reflection
measurement).
A converted impedance Z
11
completely describes a one-port DUT.
The calculation formula of the converted reflection impedances Z
ii
depends on the
waveguide circuit theory according to which Reference Impedances are calculated.
Table 5-4: Calculation of Converted Reflection Impedances
Traveling Waves Power Waves
Series Transmission Impedance
A two-port transmission parameter Z
ij
(i ≠ j) can describe a pure serial impedance
between the two ports.
Measurement Results
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