Network analyzers are used typically at high frequencies (up to over 100 GHz) to measure the scattering parameters of electrical networks. These scattering parameters are measured when a linear electrical network is being stimulated by several known electrical stimuli. These are most commonly used when dealing with the transmission or reflection of electrical signals (the previously mentioned stimuli). These are most common with microwave or radio frequencies, where the actual signal power and various energy uses are easily measured and quantified, while the specific voltage and current are much harder to measure.
When measuring audio equipment, some network analyzers can measure lower frequencies, sometimes as low as 1 kHz. There are two types of analyzers, the first of which is known is scalar (SNA for short). This device can only measure the magnitude and the various amplitude properties of a given electrical signal. A vector analyzer (sometimes called automated, or ANA) can measure both the amplitude properties and the properties of phase. This vector analyzer is mostly commonly used to measure impedance for circuits.
There is a third, newer category of network analyzers, called the Microwave Transition Analyzer (MTA), used to measure all the phase properties and amplitude properties of harmonics. By analyzing audio like that, technicians are able to better 'see' sound, specifically the interactions between various sound sources. By analyzing the harmonics of a seemingly complex sound system, users of the MTA can look at the unique and specific interactions between sounds, which produce the timbre.
Analyzers contain a sweep oscillator, a test set with multiple ports, a panel for the controlling the various metrics of measurements, a graphical display for information (both input/output data and a real-time graph of the function), and an RF cable that connects the analyzer to the electric device being tested. Before use, network analyzers require precise calibration, of which there is a large variety. Most modern network analyzers can perform any number of calibrations, the specifics of which should depend on the familiarity of the user and the type of measurements eventually desired. When calibrating, a technician will have the option of omitting isolation and averaging or 'smoothing' the results (gives more accuracy but the measurements take much longer).
Scalar network analyzers, on the other hand, are not capable of nearly as many measurements, nor does the user have nearly as much control over the input conditions. The scalar analyzer does not have any way of detecting or measuring any of the phase information - it can only measure power, something that the vector analyzers are already capable of doing. The vector analyzer's capability to measure impedance, isolation, loss/gain, and group delay for any two ports of a network with multiple ports make it an absolutely essential piece of equipment in laboratories that do electrical testing, that test machinery, or that test circuits. And no matter what the analyzer is being used for, a vector analyzer is vastly superior to a scalar analyzer, as the vector analyzer can perform all the functions of a scalar analyzer and more, with much more precision.
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