Concepts and Features
R&S
®
ZNB/ZNBT
205
User Manual 1173.9163.02 ─ 53
Table 5-19: Comparison of band pass and low pass modes
Transform
type
Band pass
Low pass
Advantages
Easiest to use: works with any set of equi-
distant sweep points
Higher response resolution (doubled)
Includes information about DC value
Real result
Impulse and step response
Restrictions
No step response
Undetermined phase
Needs harmonic grid
Use for...
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)
Scalar measurements where the sign is of
interest
DUTs with known DC value
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:
Integrate impulse
response
Obtain step
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.
5.7.2.3
Windows in the Frequency Domain
The finite sweep range in a frequency domain measurement with the discontinuous
transitions at the start and stop frequency broadens the impulses and causes side
lobes (ringing) in the time domain response. The windows offered in the "Define Trans-
form" dialog can reduce this effect and optimize the time domain response. The win-
dows have the following characteristics:
Optional Extensions and Accessories
