Learning Forum

[Russell Raldiris Torres]

When specifying a complex impedance for lumped ports in an HFSS design for FEM simulations in unit cell analysis, I get very strange results that don't look correct, specifically in the 400-420 GHz range. For example, in the port impedance I specified 76.9-1i*75.46 (per the HFSS menu setup recommendation) and then simulate. Looking at the S11 return loss we see the following:

Background, this a simple patch antenna with 3 ports.

Is there anything we need to setup prior to using complex impedances? What could be causing this type of response?

 

Any help is appreciated, thank you!

[Praneeth]

Hi Russell,

Thank you for reaching out to the Ansys learning forum.

Did you normalize the port impedance while defining the lumped port? Please share the snap of the lumped port definition in your model to help us serve you better.

Best regards,
Praneeth.

[Russell Raldiris Torres]

Hi Praneeth,

I did not perform port renormalization. I specified the port 1 and 3 in the following manner:

Let me know if there is anything else you would like me to share.

Russell

[Russell Raldiris Torres]

Hi Praneeth,

I discovered a older post with the solution. The settings had to be modified per the post: "The solution to this issue was to change the S parameter definition from the default of Generalized in Design Settings to Power which corrects the issue and plots negative return loss values."

Here is the link: /forum/forums/topic/complex-lumped-port-impedance/

My issue is resolved.