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A network analyzer is a device that tests the transmission and reflection properties on an electrical network. Components of a network include transmission lines, capacitors, switches, inductors, and resistors. Network analyzers are usually used in the characterization of two-port networks, like filters and amplifiers, but can also be used on a network with multiple ports.
The scalar network analyzer (SNA) and vector network analyzer (VNA) are the two types of network analyzer. Three main components make up each network analyzer including a signal generator, a test set, and one or more receivers. These devices mainly operate at high frequency ranges of between 9 kHz and 110 GHz but a few operate on lower frequencies of about 1 kHz. The lower frequency analyzers are best used to measure the stability analytics of open loops and audio.
Although older models lacked a signal generator, they were designed to work with external stand-alone generators through a special kind of connection known as a general purpose interface bus (GPIB) connection. This connection facilitates communication between two pieces of hardware and exchanges data between the two at a very fast rate. Modern analyzers come with not one, but two such generators so that they are able to perform more complex tests. One example of this is the mixer test, which requires both radio frequency (RF) and local oscillator (LO) signals to be generated simultaneously.
The test set plays two important roles in both analyzers because it splits the incident signal and either uses it to calibrate the signal generator in an SNA or as a phase reference for the VNA. The last component in both devices is the receiver, which works to record the test results. Both devices have a standard reference port and multiple test ports. Depending on the brand, each test port could be linked to its own receiver or shared.
The scalar network analyzer is only capable of measuring the signal’s magnitude whereas the vector network analyzer can measure the signal’s magnitude and phase. The measurements are calibrated to make the repetitions accurate. The test port that is used for reference is labeled R and the primary ones are labeled A, B and C.
Vector network analyzers are the most commonly used out of the two types. In order to ensure that the network analyzer is providing accurate results, it must be calibrated regularly. Calibration can be completed automatically or manually, however, the process must be compliant with certain standards.