Concepts and Features
R&S
®
ZNC
46
User Manual 1173.9557.02 ─ 13
Relation with S-parameters
The converted impedances Z
ii
are calculated from the reflection S-parameters S
ii
accord-
ing to:
ii
ii
i
ii
S
S
Z
Z
1
1
0
The transmission parameters are calculated according to:
,
,
2
0
0
0
0
j
i
Z
Z
S
Z
Z
Z
j
i
ij
j
i
ij
The converted admittances are defined as the inverse of the impedances.
Examples:
●
Z
11
is the input impedance of a 2-port DUT that is terminated at its output with the
reference impedance Z
0
(matched-circuit impedance measured in a forward reflec-
tion measurement).
●
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
.
You can also read the converted impedances in a reflection coefficient measurement
from the Smith chart.
3.3.2.2
Z-Parameters
The Z-parameters describe the impedances of a DUT with open output ports (i = 0). The
analyzer provides the full set of Z-parameters including the transfer impedances (i.e. the
complete nxn Z-matrix for an n port DUT).
This means that Z-parameters can be used as an alternative to S-parameters (or Y-
parameters) in order to completely characterize a linear n-port network.
2-Port Z-Parameters
In analogy to S-parameters, Z-parameters are expressed as Z
<out>< in>
, where <out> and
<in> denote the output and input port numbers of the DUT.
The Z-parameters for a two-port are based on a circuit model that can be expressed with
two linear equations:
Measurement Results
