Concepts and Features
R&S
®
ZNA
68
User Manual 1178.6462.02 ─ 12
After changing the channel settings or selecting another measured quantity, the ana-
lyzer needs some time to initialize the new sweep. This preparation period increases
with the number of points and the number of partial measurements involved. It indica-
ted in the status bar:
All analyzer settings can still be changed during sweep initialization. If necessary, the
analyzer terminates the current initialization and starts a new preparation period.
During the first sweep after a change of the channel settings, the analyzer displays an
asterisk symbol in the status bar.
5.1.4.1
Partial Measurements and Driving Mode
Depending on the measurement task and the measured quantities, the measurement
at each sweep point can consist of one or several "partial measurements" with definite
hardware settings.
●
If a single S-parameter is measured (e.g. the reflection coefficient S
11
), the ana-
lyzer can operate at fixed hardware settings. In particular, a fixed source port and
receive port is used. Each sweep point requires a single partial measurement.
See also
●
For a complete two-port S-parameter measurement (e.g. S
11
, S
21
, S
12
, S
22
) the
analyzer needs to interchange the roles of the source and receive ports. Each
sweep point requires two partial measurements.
To improve the accuracy, it is possible to insert a delay time before each partial mea-
surement.
In the default configuration, the R&S
ZNA performs a partial measurement at all sweep
points (partial sweep) before the hardware settings are changed. The next partial mea-
surement is carried out in an additional sweep ("Alternated" driving mode). However, it
is possible to reverse the order of partial measurements and sweeps ("Chopped" driv-
ing mode).
See Channel – [Channel
Config] > "Mode" > "Driving Mode".
Advantages of alternated and chopped driving mode
If the settling time between adjacent frequency points is smaller than the settling time
between the partial measurements (which is generally true), then the "Alternated" mea-
surement is faster than a normal sweep so that smaller sweep times can be set. In
contrast, an "Alternated" measurement provides a result only during the last partial
sweep.
Basic Concepts
