What is a Vector Network Analyzer and how does it work?

What is a Vector Network Analyzer (VNA)?

Vector Network Analyzers are used to test component specifications and verify design simulations to make sure systems and their components work properly together.

Today, the term “network analyzer”, is used to describe tools for a variety of “networks”. For instance, most people today have a cellular or mobile phone that runs on a 3G or 4G network. In addition, most of our homes, offices and commercial venues all have Wi-Fi, or wireless LAN “networks”. Furthermore, many computers and servers are setup in “networks” that are all linked together to the cloud. For each of these “networks”, there exists a certain network analyzer tool used to verify performance, map coverage zones and identify problem areas.

From mobile phone networks, to Wi-Fi networks, to computer networks and the to the cloud, all of the most common technological networks of today were made possible using the Vector Network Analyzer that was first invented over 60 years ago.

R&D engineers and manufacturing test engineers commonly use VNAs at various stages of product development. Component designers need to verify the performance of their components such as amplifiers, filters, antennas, cables, mixers, etc.

The system designer needs to verify their component specs to ensure that the system performance they're counting on meets their subsystem and system specifications.

Manufacturing lines use Vector Network Analyzers to make sure that all products meet specifications before they're shipped out for use by their customers. In some cases, Vector Network Analyzers are even used in field operations to verify and troubleshoot deployed RF and microwave systems.

Vector Network Anallyzer

How does a Vector Network Analyzer (VNA) work?

A Vector Network Analyzer contains both a source, used to generate a known stimulus signal, and a set of receivers, used to determine changes to this stimulus caused by the device-under-test or DUT.

The stimulus signal is injected into the DUT and the Vector Network Analyzer measures both the signal that's reflected from the input side, as well as the signal that passes through to the output side of the DUT. The Vector Network Analyzer receivers measure the resulting signals and compare them to the known stimulus signal. The measured results are then processed by either an internal or external PC and sent to a display.

A Vector Network Analyzer contains both a source, used to generate a known stimulus signal, and a set of receivers, used to determine changes to this stimulus caused by the device-under-test or DUT.

What is a Vector Network Analyzer used for?

Vector Network Analyzer’s perform two types of measurements – transmission and reflection. Transmission measurements pass the Vector Network Analyzer stimulus signal through the device under test, which is then measured by the Vector Network Analyzer receivers on the other side. The most common transmission S-parameter measurements are S21 and S12 (Sxy for greater than 2-ports). Swept power measurements are a form of transmission measurement. Some other examples of transmission measurements include gain, insertion loss/ phase, electrical length/delay and group delay. Comparatively, reflection measurements measure the part of the VNA stimulus signal that is incident upon the DUT, but does not pass through it. Instead, the reflection measurement measures the signal that travels back towards the source due to reflections. The most common reflection S-parameter measurements are S11 and S22 (Sxx for greater than 2-ports).

Learn more about Tektronix vector network analyzers »

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