Convert S parameter into TDR Impedance

[mike_bihan]

There is an equation in HFSS manual. However, there is a print error.
Could any one correct it and point out the reference source?

Z0*(1_re(S11)/(1-re(S11).

It seems not direct to me.

thanks,

 

[Supaswing]

You got the input impedance if you change _ by + but not the TDR impedance. The S-parameters being a frequency response, I dont think its should be correct but I cant help you any further, sorry.
David

 

[fantomf4]

Yep, just change the upper part of the formula, use + sign insetead of minus.
For more information look for the paper from Daniel Wu. There was a post recently about Ansoft presentations you can download from the web site.
I can't remember about the name of the post, but it was within last 2 weeks.
The paper was written for HFSS 8.5, but should not make any difference.
Hope this helps.

 

[mike_bihan]

It does not address the principle of the equation.

Also, I can not see the reason to get real part of S11.

 

[neoflash]

They do not match exactly between TDRZ and above equation. It does not looks right.