Vector Network Analyzers are a great tool for performing time domain measurements. Time domain analysis comes as a standard feature in CMT’s software, making our VNAs a sensible alternative to a traditional time domain reflectometer. 

VIDEO TRANSCRIPT:

For some applications it is important to analyze signals in time domain as well and having one instrument doing all these measurements is more convenient than owning another instrument to perform time domain analysis. So unlike a traditional TDR instrument where measurements are made by launching an impulse or a step to the DUT and then observing its response, the VNA looks at the frequency responses and then mathematically transforms to time domain using inverse Fourier transform. Also since the VNA has a better dynamic range than TDR it has been proved that a VNA can provide better accuracy even in time domain measurements for certain measurements.

One of the important use case of a time domain analysis is that it helps detect faults and discontinuity in a transmission line. As you can see from the image a BT line is shown as an example to show impedance versus distance measurements.

Here the y-axis is the impedance and x-axis is the distance. Here you can clearly observe the impedance change of 25 Ohm in the BT section and the 3.5 mm connectors. Another feature of the time domain mode is the gating function which helps or selectively remove undesired effects in time domain and see the corresponding measurements in frequency domain.

It is important to note that the time domain analysis and the gating function of standard features are available in all Copper Mountain Technologies’ VNAs.