Two port network

The Electrician

Joined Oct 9, 2007
2,970
It's not a trivial problem. The Z12 & Z21 parameters in particular require some careful algebraic manipulation.

I made use of delta-wye transformation for Z11 & Z22 analysis.

Good luck.
It looks like the OP has either solved the problem, or given up.

I think it's probably ok at this point to publish a solution.

So, t_n_k, I'd like to see your solution. If you have a pdf of your work, would you please post it?
 

t_n_k

Joined Mar 6, 2009
5,455
\(Z_{11}=Z{22}=\frac { 60 \omega^3 + 87 \omega +j \( 25 \omega^4 + 23 \omega^2 -18\)}{ 25 \omega^3 + 36 \omega }\)


\(Z_{12}=Z{21}=\frac { 40 \omega^3 + 57 \omega +j \( 25 \omega^4 + 24 \omega^2 -18\)}{ 25 \omega^3 + 36 \omega }\)


Only posting results as I am away from my desktop & scanner. Not 100% sure of Z12 Z21.
 
Last edited:

The Electrician

Joined Oct 9, 2007
2,970
I was about to point out a tiny numerical error in your results, but I see you corrected it just before I posted! :D

The red numbers are the ones where you had the tiny error!

Here's what I get:

 

Attachments

Last edited:

t_n_k

Joined Mar 6, 2009
5,455
I'm not surprised the OP gave it up. A lot of points at which the algebra can go awry. I did it all by hand with pen & paper. Required several attempts before getting consistent result using different approaches.
 

The Electrician

Joined Oct 9, 2007
2,970
I'm not surprised the OP gave it up. A lot of points at which the algebra can go awry. I did it all by hand with pen & paper. Required several attempts before getting consistent result using different approaches.
And this was for a circuit with 5 nodes. Imagine if there were even one more node. It would probably be next to impossible to solve without the assistance of an algebra software.
 

Thread Starter

xxxyyyba

Joined Aug 7, 2012
289
z11= z22 = -(w*5*i - (17*i)/w - 3/w^2 + 18)/((6*i)/w - 5);

z21 = z12 = ((((6*i)/w - 4)/(w*15*i - (51*i)/w - 9/w^2 + 54) + ((24*i)/w - 20)/(w*15*i - (51*i)/w - 9/w^2 + 54) + (w*((6*i)/w - 5)*i)/(w*5*i - (17*i)/w - 3/w^2 + 18) - (((3*i)/w - 2)*i)/(w^3*(w*5*i - (17*i)/w - 3/w^2 + 18)))*(w*5*i - (17*i)/w - 3/w^2 + 18))/((6*i)/w - 5);

I tested it using Multisim and it's good. Thank you all for help :)
 

The Electrician

Joined Oct 9, 2007
2,970
Checking your results, I find that your result for Z11, Z22 is correct:



But I have a different result than you do for Z21, Z12:



If you transcribed your Z21 result into this forum by hand, rather than by copying and pasting, it's possible that your error is just a transcription error, but I copied and pasted your expression from the forum post into Mathematica, so there shouldn't be any transcription errors there.
 

Attachments

Last edited:
Top