Network analyzer Types

1. Network analyzer Types (SNA, VNA) Introduction A network analyzer is an instrument that measures the network parameters of electrical networks. Today, network analyzers commonly measure s–parameters because reflection and transmission of electrical networks are easy to measure at high frequencies, but there are other network parameter sets such as y-parameters, z- parameters, and h-parameters. Network analyzers are often used to characterize two- port networks such as amplifiers and filters, but they can be used on networks with an arbitrary number of ports. The network analyzer is a instrument used for transmission measurements and reflection measurements. There are two types of network analyzer viz. Scalar and Vector. Transmission measurements include transmission coefficient, insertion loss, gain etc. Reflection measurements include reflection coefficient, return loss, impedance etc. Network analyzers are used mostly at high frequencies; operating frequencies can range from 1 Hz to 1.5 THz. Special types of network analyzers can also cover lower frequency ranges down to 1 Hz. These network analyzers can be used for example for the stability analysis of open loops or for the measurement of audio and ultrasonic components. The two basic types of network analyzers are scalar network analyzer (SNA)—measures amplitude properties only.  vector network analyzer (VNA)—measures both amplitude and phase  properties

2. scalar network analyzer (SNA) The Scalar Network Analyzer, SNA, can be used for measuring the scalar response of a network to an input signal. The scalar network analyzer, SNA is considerably less common in RF design circles than the VNA, but it can provide some useful insights. As the name indicates a scalar networj analyzer, SNA, measures only the amplitude response of an RF network to an applied stimulus. Scalar network analyzers can be very useful in measuring aspects like the amplitude response of a filter or other network. In this way a good insight can be obtained into a number of the aspects of the operation of the network. 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.