Agilent / HP / Keysight 8720DX

This Network Analyzer is an instrument which measures the complex transmission and reflection characteristics of two-port devices in the frequency domain.

It does this by sampling the incident signal, separating the transmitted and reflected waves, and then performing ratios that are directly related to the reflection and transmission coefficients of the two port.

Frequency is swept to rapidly obtain amplitude and phase information over a band of frequencies of interest.

This unit utilizes synthesized frequency sources to provide a known test stimulus that can sweep across a range of frequencies or power levels.

It also can perform ratioed measurements (including phase), which require multiple receivers.

It can provide a wealth of knowledge about a device under test (DUT), including its magnitude, phase, and group delay response.