Why the impedance is different?

[John_li]

Hi friends,
I want to match antenna impedance: 52.3+j*54.4 to 50Ohm in ADS, I calculate S parameters and Z parameters to get 50 Ohm. In help menu, it introduces: calZ ~Converts the results of an S-parameter simulation to Z-parameters. The S-parameters are also output.So I have thought I can get the same result in final, Actually I got the different result. I do not know what happens; would anyone help me find the root cause? And what is the case that I can use Z parameters?
Thanks

 

[BigBoss]

Z-Parameters are "Open circut parametrs" so output or input ( one of them ) should be open circuited when the other is simulated/measured.
Therefore they are different than s-parameters.ADS makes one port open circuit when it calculates the other onen therefore you see the differencies.

For instance, when you look Z11, 2nd port is open circuited or vice versa...

 

[John_li]

Oh..I see now.Thanks BigBoss for help.

 

[kspalla]

I could not understand the question clearly.
What ever may be the parameters (s,z, ABCD etc) if you calculate the antenna impedance it should be same.