For example: Agilent E4440A or Anritsu 68369

Network Analyzers

A network analyzer is an instrument that measures the network parameters of electrical networks.

Manufacturers: Keysight / Agilent, Anritsu, Advantest, Rohde and Schwarz, Wiltron, Fluke, Bird Electronics, Spirent, JDSU, Digital Lightwave, Fluke Networks, Keithley Instruments, Stanford Research Systems, Aeroflex, Chroma, Maury, Gigatronics, IFR Systems, Lecroy, Wandel and Goltermann, Pacific Measurement Inst, Scientific Atlanta