Learning Forum

[Diego Molina]

To analyze the parameters of a coplanar waveguide that operates in microwave frequency, I have to simulate the S parameters and measure the CPW characteristic impedance. The S parameters I didn't have any problem and also I made a tutorial to simulate those for my team in Brazil, link in the end of this post.

However, my main intention is to determine the characteristic impedance of the CPW. How can I get the characteristic impedance using the S parameters? Or ANSYS HFSS have some tool that can simulate the characteristic impedance direct to some coplanar waveguide?

Thanks for the help!

https://www.youtube.com/watch?v=Vwps9U_NypA&t=10s&ab_channel=DiegoMolina

[Stefano R]

Under the results option, you can plot Port Z0 to get the characteristic impedance. Make sure it is not renormalized under Excitations.

[DMARATHE]

Hi Diego

If you are simulating the CPW line and having wave ports as exciation, you can determine the characteristic impedance. You make sure that you have defined an integration line while creating the waveports, as characteristic impedances like Zpv or Zvi are not calculated by default in HFSS. 

After simulation, you can plot the Port Z0 from Results.

Thanks,

[Diego Molina]

Hi DMARATHE, thanks for the help.

I usually make terminal wave port excitations to simulate the S parameters. When you said to define an integration line, did you mean to make a modal wave port for my port excitations? If it is, how I build correctly for cpw line the line for the integration line?

[Maurice Will]

 

In the “Results” option, you can greenleafguru plot Port Z0 to obtain the characteristic impedance. Ensure herbalhighsociety it is not renormalized under “Excitations.”

 

[maryam.rahmani]

I have same issue. I have been trying different port defenision and I get different values for characteristic impedance which are way far from the value calculated by different cpw calculators. I have used terminal wave port with setting the center conductor as terminal, I have used Modal waveport by drawing line from the side ground-plane to the center conductor, I even have tried using terminal wave port by setting the center conductor as reference and set the Differencial pair and common pair ports. I still keep getting different values with different port defenision and the most important the results are completely off from my calculation (as long as online calculators) which I am pretty sure that my calculation is correct. I really appreciate if anyone can help me with that. Strugelling with this for a couple of weeks!!! Thanks!