R&S
®
ZVL
System Overview
Measured Quantities
Quick Start Guide 1303.6538.62-01
91
E
A two-port transmission parameter Z
ij
(i
S
j) can describe a pure serial impedance
between the two ports.
Relation with S-parameters
The converted impedances Z
ii
are calculated from the reflection S-parameters S
ii
according to:
,
1
1
0
ii
ii
i
ii
S
S
Z
Z
+
=
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.
Example:
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 reflection
measurement).
Tip:
You can also read the converted impedances in a reflection coefficient
measurement from the Smith chart.
3.2.3 Admittance Parameters
An admittance is the complex ratio between a current and a voltage. The analyzer
provides converted admittances: each admittance parameter is obtained from a single
S-parameter.
The converted admittance parameters describe the input admittances of a DUT with
fully matched outputs.The converted admittances are the inverse of the converted
impedances.
The analyzer converts a
single
measured S-parameter to determine the corresponding
converted admittance. As a result, converted Y-parameters cannot completely describe
general n-port DUTs:
E
A reflection parameter Y
ii
completely describes a one-port DUT. For n-port DUTs
(n>1) the reflection parameters Y
ii
describe the input admittances at ports i (i = 1 to
n) under the condition that each of the other ports is terminated with its reference
impedance (matched-circuit parameters).
E
A two-port transmission parameter Y
ij
(i
S
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
according to:
