Upload S-parameter Model (Touchstone format)

Instructions

Time gating is a technique that filters out the effect of setup reflections in post-processing. I recommend using the S-parameter time gating tool with the following steps:

Step 1. Identify the timing of the setup.
Time gating can not be performed based on the S-parameter data alone, knowledge of the test setup is required. Specifically, the time it takes for unwanted reflections is needed. This can be determined by measuring the distance to an expected reflection and dividing by the propagation velocity. The time delay should be with respect to the VNA port calibration reference.

Step 2. Enter timing information.
Using the reflection timing of the setup earlier, enter the Time Cutoff and Ramp settings in the tool. The Ramp is optional (set to zero if not wanted) but it can give a smoother transition and reduce the effect of Gibbs ringing.

Step 3. Select and upload the S-parameter file.
Click the "Choose File" button and navigate to a touchstone formatted S-parameter file with an ".s*p" file ending. Click "Open" with the file selected and wait for the processing to complete. Once completed, a new S-parameter file will be downloaded with time gating filtering applied.

Step 4. Review the data plots.
Select the Trace and Format (Time Domain, Complex, Smith, or Log) of the plot to inspect the effect of the time gating filter. The Time Domain format, which shows the impulse response of the S-parameter using and inverse FFT, is especially useful for confirming that the filter settings are correct. See an example below with a Time Cutoff of 4.5 ns and a Ramp of 0.5 ns. If the filter settings need to be changed, then refresh the page and repeat Steps 2 through 4.