9.2 Receiver Bandwidth
A vector network analyzer (VNA) measurement is a narrow-band or frequency-selective measurement.
Only one frequency of interest is analyzed at a time. To do so, the receiver is configured to be
sensitive to exactly the same frequency that is currently generated by the signal generator. All other
frequencies or side-bands are neglected. In reality, there is always some finite side-band content that
will be included in the measurement result. The RBW setting (Receiver Bandwidth or Resolution
Bandwidth) defines the width of the narrow-band filter used to generate the result.
A high RBW value, will result in a fast measurement but more noise. The wider bandwidth results in
more noise-energy included in the measurement and therefore in a higher noise-floor level. A low
RBW value offers more noise-rejection but it will increase the measurement time.
The following picture shows the shape of the frequency-selective receiver filter for different RBW
values:
Figure 9-2: Graphical representation of the different RBW values.
The Receiver Bandwidth setting in the Bode Analyzer Suite is actually a maximum RBW
setting. The system will automatically reduce the RBW value when it measures at a
frequency below the max. RBW value. It is impossible to measure e.g. at 10 Hz using a
receiver bandwidth setting greater than 10 Hz.
Use the setting to adjust the maximum RBW used during the
measurement.
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OMICRON Lab
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