R&S ZNB Series User Manual page 224

®
R&S ZNB/ZNBT
point at zero frequency (DC value). The time domain result is complex, with an
undetermined phase depending on the delay of the signal.
●
Low pass mode: The measurement results are continued towards f = 0 (DC value)
and mirrored at the frequency origin so that the effective sweep range (and thus
the response resolution) is more than doubled. Together with the DC value, the
condition of equidistant sweep points implies that the frequency grid must be har-
monic. Due to the symmetry of the trace in the frequency domain, the time domain
result is harmonic.
See also
Two different types of response are available in low pass mode; see below.
Table 4-19: Comparison of band pass and low pass modes
Transform
type
Advantages
Restrictions
Use for...
Impulse and step response
In low pass mode, the analyzer can calculate two different types of responses:
●
The impulse response corresponds to the response of a DUT that is stimulated
with a short pulse.
●
The step response corresponds to the response of a DUT that is stimulated with a
voltage waveform that transitions from zero to unity.
The two alternative responses are mathematically equivalent; the step response can
be obtained by integrating the impulse response:
The step response is recommended for impedance measurements and for the analysis
of discontinuities (especially inductive and capacitive discontinuities). The impulse
response has an unambiguous magnitude and is therefore recommended for most
other applications.
User Manual 1173.9163.02 ─ 62
Chapter 4.7.2.4, "Harmonic
Band pass
Easiest to use: works with any set of equi-
distant sweep points
No step response
Undetermined phase
Scalar measurements where the phase is
not needed
DUTs that do not operate down to f = 0 (e.g.
pass band or high pass filters)
Optional extensions and accessories
grid", on page 225.
Low pass
Higher response resolution (doubled)
Includes information about DC value
Real result
Impulse and step response
Needs harmonic grid
Scalar measurements where the sign is of
interest
DUTs with known DC value
Integrate impulse
response
Obtain step
response
Concepts and features
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