Rohde & Schwarz 1145.1010.04/05/06, Operating Manual

Page: 142 / 813

Measured Quantities R&S
®
ZVA/ZVB/ZVT
1145.1084.12 3.32 E-1
received waves are at different frequencies.
•
A ratio of two arbitrary waves that is not an element of the S-matrix (e.g. a ratio of the form a
i
/a
j
)
is needed.
The notation for ratios includes the two waves with their directions and test port numbers. Additionally,
the source port must be specified. In analogy to wave quantities, the letter a indicates an outgoing
wave, b an incoming wave.
Examples:
•
b2/a1 Src Port 1 is the ratio of the incoming wave at port 2 and the outgoing wave at port 1 b
2
and a
1
and corresponds to the S-parameter S
21
(forward transmission coefficient).
•
b1/a1 Src Port 1 is the ratio of the wave quantities b
1
and a
1
, measured at PORT 1, and
corresponds to the S-parameter S
11
(input reflection coefficient).
Balance - Unbalance Conversion
Balance-unbalance conversion is the simulation of one or more balance-unbalance transformers
(baluns) integrated in the measurement circuit in order to convert the DUT ports from an unbalanced
state into a balanced state and virtually separate the differential and common mode signals. The
analyzer measures the unbalanced state but converts the results and calculates mixed mode
parameters, e.g. mixed mode S-parameters. No physical transformer is needed.
To perform balanced measurements, a pair of physical analyzer ports is combined to form a logical
port. The balanced port of the DUT is directly connected to the analyzer ports