Concepts and features
R&S
®
ZND
202
User Manual 1173.9557.02 ─ 61
Recalibration Required
Although this is a software option, the R&S
ZND has to be recalibrated at Rohde &
Schwarz service to comply with the specifications of the data sheet.
4.7.5
Time domain analysis
Option R&S
ZND-K2
The network analyzer measures and displays complex S-parameters and other quanti-
ties as a function of the frequency. The measurement results can be filtered and math-
ematically transformed to obtain the time domain representation, which often gives a
clearer insight into the characteristics of the DUT.
Time domain transforms can be calculated in band pass or low pass mode. For the lat-
ter, the analyzer offers the impulse and step response as two alternative transformation
types. A wide selection of windows can be used to optimize the time domain response
and suppress side lobes due to the finite sweep range. Moreover, it is possible to elimi-
nate unwanted responses using a time gate and transform the gated result back into
the frequency domain.
For a detailed discussion of the time domain transformation including many examples,
refer to the application note 1EP83 which is available on the R&S internet at
www.rohde-schwarz.com/appnotes/1EP83
.
Trace selection
Select a reflection parameter S
ii
to perform a time domain reflectometry (TDR) mea-
surement, e.g. to detect cable faults. To measure the impedance of a network, you can
select a
Z←S
ii
.
Select a transmission parameters S
ij
(i≠j) to perform a time domain transmission (TDT)
measurement, e.g. for measuring antennas.
For TDR traces and if distance is used as the x axis, the x value indicates the
one-way
path to the reflection.
4.7.5.1
Chirp z-transformation
The Chirp z-transformation that the analyzer uses to compute the time domain
response is an extension of the (inverse) Fast Fourier Transform (FFT). Compared to
the FFT, the number of sweep points is arbitrary (not necessarily an integer power of
2), but the computation time is increased by approx. a factor of 2. This increased com-
putation time is usually negligible compared to the sweep times of the analyzer.
The following properties of the Chirp z-transformation are relevant for the analyzer set-
tings:
●
The frequency points must be equidistant.
Optional extensions and accessories
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