Scalar Network Analyzer, SNA
- notes and overview of the scalar network analyser, SNA detailing what it is, how it works and how it may be used.
As the name indicates, a scalar network analyser or SMA is a form of RF network analyzer that only measures the amplitude properties of the device under test. In view of this it is the simpler of the various types of RF network analyser.
Effectively, a scalar network analyzer, SNA, works just as a spectrum analyzer in combination with a tracking generator. When a tracking generator and spectrum analyser are used together, their operation is electrically closely linked.
The tracking generator generators a swept signal on exactly the same frequency that the spectrum analyser is receiving. Thus if the output from the tracking generator was connected directly to the input of the spectrum analyzer, then a constant line would be seen across the screen of the analyzer indicating the amplitude of the tracking generator output.
If a device is placed between the two items, then the spectrum analyser will note any amplitude variations. In this way for example, the response of a filter can be plotted. The constant output of the tracking generator will pass into the filter, where the response of the filter will change it according to the frequency and the response of the filter at that frequency, and in this way the spectrum analyzer will be able to display the response of the filter. From this it can be seen that scalar network analyzers, SNA, are very useful for measuring the amplitude response of a variety of components.
By Ian Poole
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