Scattering Parameters - Lesson 12

[@jamesm6951]

Very good video series. You and Behzad Razavi are like the only two electrical engineers I've seen that can communicate tough concepts clearly.

[@emviso]

Thank you - I appreciate the encouragement!

[@valentinaangelini8473]

You saved me!!!! Amazing explanation!!!!! Thanks for everything

[@yanhairen7293]

very insightful

[@asht7788]

Amazing explanation, you are a lifesaver

[@emviso]

I'm glad it helped - thanks for the feedback!

[@srujaniam9762]

Thank you. Thank you very much

[@emviso]

You're very welcome - thank you for the comment!

[@blakely1317]

brilliant. thanks a lot

[@bilalalsyed2291]

At 1:47 it says the signal exited at port 1 and input was at port 2. Shouldn't this be the other way around?

[@yahiahatem4898]

yes, I think it should

[@-Apostolos]

Excellent video, nice work! Regarding the sum at 6:12, shouldn't it be Σ(|S_ij|^2) rather than Σ(|S_ij|) since we're talking about the squared magnitudes of the elements of the S-matrix?

[@emviso]

You are quite right - that's a typo. The magnitude of S_ij should be squared in the last equation on that screen. Thank you for pointing that out!

[@-Apostolos]

@@emviso Thank you for clarifying! On that note, is the result of this summation sufficient to declare a network lossless or lossy? I've noticed some resources (e.g. page 11 "From unitary condition follows": classes.engr.oregonstate.edu/eecs/fall2017/ece580/Lecture%20Notes/Andreas%20WeisshaarECE580_guest-lecture.pdf ) also state some properties about the conjugates of S-parameters. Are these additional conditions, or does the summation alone always imply that the equations involving the conjugates describe the same thing?

[@emviso]

@@-Apostolos This is sufficient, as long as the characteristic impedance is equal at every port.

[@-Apostolos]

@@emviso Thanks, one (hopefully) final question regarding the definition of the incident power waves: en.wikipedia.org/wiki/Scattering_parameters#A_definition The equation k_i = (√|ℜ{Z_i}|)^-1 involves the real part of the impedance (since R = ℜ{Z}). But why is it wrapped in |...|? If R ≥ 0, why do we need to take the absolute value of the resistance when |R| will always be equal to R?

[@-Apostolos]

FYI, I looked back at the original papers where the equation was introduced, and apparently the absolute value takes care of R < 0. R can sometimes be considered negative when we're dealing with active networks, such as active reflections (|S11| > 1).

[@fanpeter-z3c]

thanks, ur video conclude my professor's 40 miniutes lectucre which I have no idea what she is saying

[@emviso]

I'm glad you found it helpful!

[@ivane1168]

too bad mic, better to use a clips-mic.