Rohde & Schwarz R&S ZNB - Page 130

Concepts and Features
R&S
®
ZNB/ZNBT
130User Manual 1173.9163.02 ─ 53
ence impedances for the differential and common mode at each balanced port. Both
steps can be done in a single "Balanced Ports" dialog. The most commonly used bal-
anced port configurations and impedances are predefined and can be selected in the
"S-Parameter Wizard".
Depending on the test setup, the analyzer provides different types of mixed mode
parameters; refer to the following sections for details.
5.3.6.2 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).
●
S
<mout><min>21
is the mixed mode forward transmission coefficient, defined as the
ratio of the wave quantities b
2
(mode mout) to a
1
(mode min) (forward measure-
ment with matched output and a
2
= 0).
●
S
<mout><min>12
is the mixed mode reverse transmission coefficient, defined as the
ratio of the wave quantities b
1
(mode mout) (reverse measurement with matched
input, b
1
' in the figure above and a
1
= 0) to a
2
(mode min).
●
S
<mout><min>22
is the mixed mode output reflection coefficient, defined as the ratio of
the wave quantities b
2
(mode mout) (reverse measurement with matched input, b
2
'
in the figure above and a
1
= 0) to a
2
(mode min), measured at PORT 2.
Measurement Results