VNA Concepts and Features
R&S
®
ZNL/ZNLE
226
User Manual 1178.5966.02 ─ 07
It is possible to assign arbitrary, independent reference impedance values to the differ-
ential and common mode of the single balanced port.
Example:
Bal.
port
Differential mode
Z
ref
= Z
0d
Common mode
Z
ref
= Z
0c
DUT
Balanced port:
Log.
VNA
port
The "Balanced Ports" dialog allows you to switch to balanced operation and to define
the reference impedances the differential and common mode.
Depending on the test setup, the analyzer provides different types of mixed mode
parameters; refer to the following sections for details.
8.3.5.2
Mixed Mode Parameters
Mixed mode parameters are an extension of normal mode parameters (e.g. S-parame-
ters, impedances and admittances) for balanced measurements. The analyzer can
measure mixed mode parameters once a balanced port configuration is selected.
Mixed mode parameters are used to distinguish the following three port modes:
●
s: Single-ended (for unbalanced ports)
●
d: Differential mode (for balanced ports)
●
c: Common mode (for balanced ports)
The notation of a general S-parameter is S
<mout><min><out><in>
, where <mout> and <min>
denote the output and input port modes, <out> and <in> denote the output and input
port numbers.
Meaning of 2-port mixed mode S-parameters
The mixed mode 2-port S-parameters can be interpreted as follows:
●
S
<mout><min>11
is the mixed mode input reflection coefficient, defined as the ratio of
the wave quantities b
1
(mode mout) to a
1
(mode min), measured at PORT 1 (for-
ward measurement with matched output and a
2
= 0).
Measurement Results
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