TDR – Frequency Domain S11 Conversion to Time Domain TDR

tdr

Below we see the S11 plot of a transmission line, the Wikipedia definition of the reflection coefficient as a function of S-params.

As I see it, the S-param frequency domain plot comes from the time domain steady state.

TDR is time domain in every moment from the start (transient).

So how can we convert from S-param (steady state) to TDR (transient)?

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Best Answer

You get the time domain TDR by taking the inverse transform of the frequency domain S11 data. This is related to the fact that the impulse response of a network is equal to the Fourier transform of its frequency response. Many Vector Network Analyzers have this function built in and usually labeled "Transform". You can find the details by Googling "convert S11 data to TDR". One good source is: https://cdn.rohde-schwarz.com/pws/dl_downloads/dl_application/application_notes/1ez44/1ez44_0e.pdf.

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