Concepts and Features
R&S
®
ZNC
48
User Manual 1173.9557.02 ─ 13
n) under the condition that each of the other ports is terminated with its reference
impedance (matched-circuit parameters).
●
A two-port transmission parameter Y
ij
(i
≠
j) can describe a pure serial impedance
between the two ports.
Relation with S-parameters
The converted admittances Y
ii
are calculated from the reflection S-parameters S
ii
accord-
ing to:
ii
ii
ii
i
ii
Z
S
S
Z
Y
/
1
1
1
1
0
The transmission parameters are calculated according to:
99
...,
,
1
,
,
,
/
1
2
0
0
0
0
j
i
j
i
Z
Z
Z
S
Z
Z
S
Y
ij
j
i
ij
j
i
ij
ij
Examples:
●
Y
11
is the input admittance of a 2-port DUT that is terminated at its output with the
reference impedance Z
0
(matched-circuit admittance measured in a forward reflec-
tion measurement).
●
The extension of the admittances to more ports and mixed mode measurements is
analogous to S-parameters. Y
dd22
is the differential mode input admittance at port 2
of a DUT that is terminated at its other ports with the reference impedance Z
0
.
You can also read the converted admittances in a reflection coefficient measurement
from the inverted Smith chart.
3.3.3.2
Y-Parameters
The Y-parameters describe the admittances of a DUT with output ports terminated in a
short circuit (V = 0). The analyzer provides the full set of Y-parameters including the
transfer admittances (i.e. the complete n x n Y-matrix for an n port DUT).
This means that Y-parameters can be used as an alternative to S-parameters (or Z-
parameters) in order to completely characterize a linear n-port network.
2-Port Y-Parameters
In analogy to S-parameters, Y-parameters are expressed as Y
<out>< in>
, where <out> and
<in> denote the output and input port numbers of the DUT. In analogy to Z-parameters,
the Y-parameters for a two-port are based on a circuit model that can be expressed with
two linear equations:
2
22
1
21
2
2
12
1
11
1
V
Y
V
Y
I
V
Y
V
Y
I
Measurement Results
