Vector Network Analyzers

Vector network analyzers measure both magnitude and phase of transmitted and reflected signals, which is what allows full characterisation of impedance, insertion loss, return loss and group delay.

Keysight and Siglent cover this range. Frequency coverage and port count are the starting point, with two ports sufficient for most filter and cable work and four required for differential or balanced devices. Dynamic range determines how deep a stopband you can actually see. Remember that a VNA is only as good as its calibration, so budget for the correct mechanical kit or ECal module and the right connector interface, since an uncalibrated measurement describes your cables rather than your device.