I want to know the attenuation constant of a microstrip line. And I measured s11, s21, s22.
Can I draw attenuation of the line by subtracting both mismatch losses at the port and the load from s21 as shown below?
Mismatch loss at the port: sm1=10*log10((1-10.^(s11(:,2)./10)))
Mismatch loss at the load: sm2=10*log10((1-10.^(s22(:,2)./10)))
attenuation=s21-sm1-sm2
attenuation constant=ling length*attenuation
You can convert the S-parameters to RLGC, then extract alpha. There is a function in MATLAB that can do this: https://uk.mathworks.com/help/rf/ug/s2rlgc.html
Should also be possible in ADS.
I believe, as long as you have calibrated the VNA to the ports of your device, it is as straight forward as using RLCG to extract what you are interested in.
My open-source software project called SignalIntegrity (https://pypi.org/project/SignalIntegrity/) has a fitter that will fit RLGC as well as loss-tangent and skin-effect loss. You simply supply a two-port s-parameter file.
All of the details of how I do this are in my recently published book "S-Parameters for Signal Integrity" (Book S-Parameters for Signal Integrity
), but like I said, the source code for all of this is in the project.I added a screenshot of this.
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