| Electronics > Beginners |
| S parameters of a connector!! |
| (1/1) |
| blackout123:
Hello everyone, I am desperately trying to find the Scattering parameters of a connector. For that purpose, I designed two lines, one of length L and the other of length 2L. First idea was to use the T parameters to find the connector’s S parameters and the idea was as follow: Tmeasured_L = Tc Tline Tc Tmeasured_2L = Tc Tline Tline Tc And then: [Tmeasured_2L] * [Tmeasured_L]-1 = Tc Tline Tc-1 = Ta [Tmeasured_L]-1 * Ta = Tc-1 Tc-1 and then invert everything and square root… this is the matlab code but the result cannot be correct Hello everyone, I am desperately trying to find the Scattering parameters of a connector. For that purpose, I designed two lines, one of length L and the other of length 2L. First idea was to use the T parameters to find the connector’s S parameters and the idea was as follow: Tmeasured_L = Tc Tline Tc Tmeasured_2L = Tc Tline Tline Tc And then: [Tmeasured_2L] * [Tmeasured_L]-1 = Tc Tline Tc-1 = Ta [Tmeasured_L]-1 * Ta = Tc-1 Tc-1 and then invert everything and square root… this is the matlab code but the result cannot be correct |
| rfeecs:
This is at least the fourth time you have posted the exact same question, previously under the user name RFbeginner. I guess you were not happy with my answer: https://www.eevblog.com/forum/beginners/s-parameters-of-a-connector/msg2618190/#msg2618190 Your equations are wrong. That's why your program doesn't work. Consider this: You have two unknown two ports: Tc and Tline These are passive and reciprocal, so for each one S12=S21 Tline is symmetric, so S11=S22 So you have 5 unknowns: 1. Tc(S11) 2. Tc(S21) = Tc(S12) 3. Tc(S22) 4. Tline(S11) = Tline(S22) 5. Tline(S21) = Tline(S12) You are measuring 2 symmetric devices, so S11=S22 and S12=S21 in your measurements. So you have 4 knowns to get 5 unknowns. It doesn't work. You have to make some assumptions. A common assumption is Tline is a perfectly matched 50 ohm line. S11=S22=0. That eliminates one of your unknowns and gives you 4 knowns and 4 unknowns. That is solvable. Now you just need to do the math correctly. It will be horribly messy algebra. |
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