| Electronics > Beginners |
| Even-odd mode analysis |
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| promach:
Could anyone show an actual circuit example using the even-odd mode analysis concept ? By the way, I am reading this useful textronix TDR impedance measurement application note |
| rfeecs:
It is used all the time in analyzing differential pairs, like the inputs to op-amps. Same as differential mode / common mode. It is mentioned on the last page here: http://www.ittc.ku.edu/~jstiles/723/handouts/Odd%20Even%20Mode%20Analysis.pdf Also used in analyzing coupled transmission lines: http://emlab.uiuc.edu/ece451/notes/coupled.pdf https://www.ewh.ieee.org/r5/denver/rockymountainemc/archive/2000/diffimp.pdf And coupled line structures like directional couplers: http://www.ittc.ku.edu/~jstiles/723/handouts/Analysis%20and%20Design%20of%20Coupled%20Line%20Couplers.pdf |
| T3sl4co1l:
An example would be a VNA with a single measured port and an open/short/terminated far port. A single port is just an impedance, but by seeing how that impedance changes due to the far port's impedance, you obtain the transfer characteristics (s21). Tim |
| rfeecs:
--- Quote from: T3sl4co1l on March 17, 2019, 10:54:18 pm ---An example would be a VNA with a single measured port and an open/short/terminated far port. A single port is just an impedance, but by seeing how that impedance changes due to the far port's impedance, you obtain the transfer characteristics (s21). Tim --- End quote --- This would only work if you were measuring a reciprical network (S21 = S12). Then you have three measurements and three unknowns. For an amplifier or a network with isolators / circulators, it won't work. Also, I don't see how this is an example of even / odd mode analysis. |
| promach:
I just found this nice article about even-odd mode analysis for Wilkinson Power Divider Before reaching the even-odd mode analysis, I am bit confused with slides 10 and 11. For slide 10, why "250-ohm transmission line loads in parallel" ? For slide 11, why "quarter-wave transformer could convert RS to 2RS so we can match input ports" ? |
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