# Homework Help: Double Stub Matching Using Smith Charts

1. Feb 22, 2010

### xcvxcvvc

I'm going to class, and I'll ask my teacher. There is not sense in you using your time on this problem anymore, so don't! I'll post the answer to my question after I find it in case someone ever stumbles on this thread with the same question I had. OK HERE IS THE ANSWER: My teacher accidentally gave an unsolvable question :P.

1. The problem statement, all variables and given/known data
A 50 ohm line is terminated in a 40 ohm load.
Two shorted stubs are to be used in parallel with the line to match the load and line. One stub should be located in parallel with the load , and the other should be located1/4 wavelength from the load.
Find the input impedance of each stub.

3. The attempt at a solution

I know the circle I drew is retarded looking, but it gets the point across. I plotted the normalized impedance(.8) and converted it to admittance. Next, I drew a unit circle shifted toward the load by .25 wavelengths. After that, I see no way I can add an imaginary admittance to my real 1.25 so that it will be on the predictive unit circle (in other words, so that when that total admittance is shifted .25 wavelengths toward the generator, it will be on the unit circle with 1 real, xL reactive.)

http://img687.imageshack.us/img687/7161/smithchart.jpg [Broken]

Last edited by a moderator: May 4, 2017