R&S ZVB - Page 181

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ZVA / R&S
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ZVB / R&S
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ZVT GUI Reference
Trace Menu
Operating Manual 1145.1084.12 – 30 166
expression represents a voltage. Examples for voltage-type expressions are all terms proportional
to a wave quantity (e.g. 1.1*Data, if a wave quantity is measured) or to a stimulus value of a
power sweep. If Show As: Power is selected in the More Wave Quantities dialog, the result is
converted into a linear power before the selected trace format is applied. Otherwise no conversion
is performed, and dB Mag results are referenced to 1 μV.
 If Result is Wave Quantity is disabled the analyzer assumes that the result of the mathematical
expression is dimensionless. Examples for dimensionless expressions are all terms proportional
to ratios of wave quantities, e.g. Data / Mem2[Trc1]. The selected trace format is applied without
previous conversion.
Result is Wave Quantity acts on the result of the mathematical expression only. Wave quantities and
power sweep stimulus values always enter into the expression as voltages.
Effect of Result is Wave Quantity and numeric example
In the More Wave Quantities dialog, the Show as: control element specifies whether wave quantities are
displayed as voltages or equivalent power levels, using the port impedances for a conversion between the
two representations. Result is Wave Quantity is relevant for mathematical traces displayed in units of dBm
(Show as: Power and trace format dB Mag):
 If Result is Wave Quantity is on (checked), the mathematical trace values <W> are interpreted as
voltages and first converted into equivalent power levels (<W> —> <P> = <W>
2
/Re(Z
0
)). Results
in dB Mag format are calculated according to <P>
log
= 10 * log (<P>/1mW).
 If Result is Wave Quantity is off, the mathematical trace values <W> are interpreted as
dimensionless quantities. Results in dB Mag format are calculated according to <W>
log
= 20 * log
(<W>).
Example: A mathematical trace value amounts to 1 (real value); the port impedance is 50 Ω. If Result is
Wave Quantity is on, the analyzer assumes the trace value to be 1 V, which is converted into a linear
power of 20 mW, corresponding to approx. 13 dBm. With Result is Wave Quantity off, the trace value 1 is
directly converted into a logarithmic power of 0 dBm.
See also example for CALCulate<Chn>:MATH:WUNit:STATe ON | OFF.
Time Domain
Opens a submenu to view the measurement results as a function of time. The time domain transformation
requires option ZVAB-K2, Time Domain.
Time domain transformation
The network analyzer measures and displays complex S-parameters and other quantities as a function of
the frequency. The measurement results can be filtered and mathematically transformed in order 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 bandpass or lowpass mode. For the latter 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 sidelobes due to the finite sweep range.
Moreover, it is possible to eliminate unwanted responses by means of 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 1EZ44 which is posted on the R&S internet.