Difficulty getting s2rlgc to work

Hello -

Using Matlab R2021b.

I am attempting to use the s2rlgc function. I have high quality two port data collected with a fully calibrated VNA in a 50 ohm environment from a simple transmission line on a test board specifically built for measuring a clean trace. This file was saved as a Touchstone file and imported with the sparameters() function (original data attached).

When I attempt to run the data through s2rlgc, the routine complains that the data must be passive. I assure you that it is, but just in case, I tried running it through makepassive() before extracting the parameters. The output of makepassive does not seem to be acceptable to to s2rlgc, which complains about the incoming parameters (S_PARAMS must be numeric).

This would seem to be the ideal circumstances for extracting transmission line parameters, but so far I have not been able to get it to succeed.

Answer 1

[Hornett]

If the makepassive function is not producing acceptable results for the s2rlgc function, you may need to investigate further to ensure that the S-parameters data is correctly formatted and meets the requirements of the s2rlgc function. To address the error message you're receiving, it's important to ensure that the S-parameters data is passive. In addition to using the makepassive function, you should check the passivity of the S-parameters using the isPassive function.

Read more about the function here: https://www.mathworks.com/help/control/ref/dynamicsystem.ispassive.html