HFSS: who undestands this?

[beetro78]

The attached file...is the model of a CPW on LiNb03 (not a real RAR..just change the extension in .HFSS).

Everything in the model is symmetrical..I deisgned a straight CPW line and I put two identical waveport at its ends to analysze its behaviour.

What happende is very strange: THE RESULTS are not SYMMETRICAL..results from port1 are different from port2...this does not match with the reciprocity theorem... so or I or HFSS or both are wrong!

Even the MODAL field computed by HFSS is different in the TWO identical ports on the same line

Does anybody knows why? Where is the mistake? What did I do wrong?

Please help me...

Thank you

 

[rfmw]

Might be that you'll have to expand the port rectangle to the outer sides of the substrate.


EDIT: admins move this topic to a ELMG forum, cos 99% people dealing with HFSS will miss this one...

 

[beetro78]

Thank you.

I made the slim slots just because I've seen the CPW tutorial, you talk about: the slim slots make the port edge touch the grounds in order to avoid that HFSS calculate the TEMs mode of a 3 signal trace line.

Is not this the way to create the inward "fingers"?

Probably, I did not get actually the meaning of inward pointing finger, reading the tutorial. I didn't understand it from the slides. Could you please explain me?

many thanks.