# Homework Help: Smith chart question

1. Oct 29, 2009

### likephysics

1. The problem statement, all variables and given/known data

The characteristic impedance of a given lossless transmission line is 75 ohms. use a smith chart to find the input impedance at 200Mhz of such a line that is (a)1m long and open circuited and (b) 0.8m long and short circuited. Then (c) determine the corresponding input admittances for the lines in part (a) and (b).

2. Relevant equations

3. The attempt at a solution

I can find the answer for the short circuit case. The R=0 circle is the short ckt circle. I just started from the left most part of the smith chart and then moved a distance of (l/lambda)=0.53 , to find the input impedance.

But for open circuit, the circle degenerates to a point. I am not sure how to proceed.

Also, the analytical results don't agree with the graphical results. So I am going wrong somewhere. Any help?

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