Network Analyzers
A network analyzer is an instrument used to analyze the properties of electrical networks, especially those properties associated with the reflection and transmission of electrical signals known as scattering parameters (S-parameters). Network analyzers are used mostly at high frequencies; operating frequencies can range from 9 kHz to 110 GHz.
The two main categories of Network Analyzers are:

• Scalar Network Analyzer (SNA) - Measures amplitude properties only
• Vector Network Analyzer (VNA) - Measures both amplitude and phase properties

A VNA may also be called a gain-phase meter or an Automatic Network Analyzer. An SNA is functionally identical to a spectrum analyzer in combination with a tracking generator. As of 2007, VNAs are the most common type of network analyzers, and so references to an unqualified 'network analyzer' most often mean a VNA.