Hello people I'm new to this forum. Can someone please take a look at my solution to the problem I have attached. my lecturer said I am on the right track but my answer is wrong. I have till Friday to get the right solution. I would really appreciate it if someone can post up the correct answer and solution for this one. Thanks

 

The diagram is a little unclear to me.
The values of the given 's' parameters appear to indicate that Port 1 has an additional shunt impedance of 50 ohms as well as the anticipated source impedance - presumably also 50 ohms. This makes the apparent impedance seen at the source end of the line a value of 25 ohms.
Is this the correct interpretation?

 

Sorry so late response. Yes i think your interpretation is correct if you are talking about the input impedance as seen looking in to port 1.