System Overview
R&S
®
ZVT
75
Getting Started 1300.0045.62 ─ 10
3.3.2.10
Ratios
A ratio measurement provides the complex ratio of any combination of transmitted or
received wave amplitudes. Ratios complement the S-parameter measurements, where
only ratios of the form b
I
/a
j
(ratio of the incoming wave to the outgoing wave at the test
ports I and j of the DUT) are considered.
Examples for using ratios
A measurement of ratios is particularly suitable for the following test scenarios:
●
The test setup or some of its components (e.g. active components or non-recipro-
cal devices) do not allow a system error correction so that a complete S-parameter
measurement is not possible.
●
The test setup contains frequency-converting components so that the transmitted
and the 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 num-
bers. Additionally, the source port must be specified. In analogy to wave quantities, the
letter a indicates an outgoing wave, b an incoming wave.
Examples:
●
b
2
/a
1
Src Port 1 is the ratio of the outgoing wave b
2
at port 2 and the incident wave
a
1
at port 1; this corresponds to the S-parameter S
21
(forward transmission coeffi-
cient).
●
b
1
/a
1
Src Port 1 is the ratio of the wave quantities b
1
and a
1
, measured at PORT 1;
this corresponds to the S-parameter S
11
(input reflection coefficient).
3.3.2.11
Unbalance-Balance Conversion
Unbalance-balance conversion is the simulation of one or more unbalance-balance
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.
With option R&S ZVA-K6, True Differential Mode, the analyzer can generate balanced
waves at arbitrary reference planes in the test setup and determine balanced results
such as S-parameters, wave quantities and ratios. The true differential mode also pro-
vides two additional sweep types, the "amplitude imbalance" and "phase imbalance"
sweeps. What is said below is valid for both the simulated balanced mode and the true
differential mode.
Measured Quantities
