Rohde & Schwarz 1145.1010.04/05/06, Operating Manual

Page: 144 / 813

Measured Quantities R&S
®
ZVA/ZVB/ZVT
1145.1084.12 3.34 E-1
Mixed Mode Parameters
Mixed mode parameters are an extension of normal mode parameters (e.g. S-parameters, impedances
and admittances) for balanced measurements. The analyzer can measure mixed mode parameters as
soon as a balanced port configuration is selected.
Mixed mode parameters are used to distinguish the following three port modes:
s: Singe-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 (forward 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 measurement 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.
If <mout> is different from <min>, the S-parameters are called mode conversion factors.
Mixed Mode Parameters for Different Test Setups
The mixed mode parameter types available depend on the measured device and the port configuration
of the analyzer. The following examples of mixed more parameters can all be obtained with a 4-port
analyzer.
1. DUT with only single-ended ports: No balanced port definition necessary, the analyzer provides
single-ended multiport parameters.
2. DUT with one balanced port: Only reflection and mode conversion measurements with
differential and common mode parameters.