You can add the impedance data as data sets, one for resistance and one for the reactance. Then you can add an impedance boundary condition and in the entry field type pwl(datasetname, freq). You can as well create an anisotropic impedance boundary where you can link to another HFSS design that extract the impedance data

Dear Ibrahim thanks a lot for your precise response... 

Hello Hadi, my answer would be same as Ibrahim's, he did a great job, follow his answer. Good luck.

 Dear Al-Rizzo thank a lot for your response...

Ibrahim:

I get the following error message when I try your answer to Hadi's issue, "datasetname is not a defined dataset in this context."

Thanks in advance for any help you can provide.

EDIT: I resolved the issue. 

So the problem is resolved?

Yes. Thank you.

 Hi, Ibrahim

I get an error message. 

"Boundary 'Imped1': Resistance cannot be a function of intrinsic variable 'Freq' "

Dont know what should I do to solve this problem. 

Thanks in advance for helping me. 

By the way, I am using Eigenmode to run  the simulation. 

Can you please share the HFSS file to take a look?

I just want to use Eigenmode instead of Driven mode to run the simulation. 

So, if I put the right impedance on both side of the waveguide, I should be able to recover the same result of simulation from Driven mode. 

Yes you cannot assign a frequency dependent boundary when you use the eigenmode solver with HFSS. Just specify the impedance value at the eigenmode resonance of concern

Okay, thanks for your help. 

Thank you Ibrahim T. Nassar ! After this long time, your response was so helpful for me!

Hi, I have a similar issue in Circuit: one of the capacitance values should be changed synchronously with another parameter.

1. I have created the dataset in Design with the name "Length_C_data" this contains the distance as the X column in mm and capacitance in pF as Y

2. when I'm trying to set the variable "Cap1" which is used in the schematic as:

"pwl(Length_C_data, 55)" it immediately shows the error "Length_C_data is not defined dataset name in this context".

thanks for the help in advance.