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Oscillations in the S-parameters results

    • Liam1

      Hello all,

      I am simulating a structure with two lumped ports:

      Solution type: terminal

      Radiation boundary: a quarter wavelength away from each face


      I don't understand where all these oscillations and resonances come from. When I change the size of the radiation boundary to be exactly as large as the structure (offset=0, all the faces touch the surface of the structure), the oscillations disappear:

      I tried different meshing techniques and the oscillations are still there.

      Any idea what's causing this and how to resolve?


      Thank you





    • slouie
      Ansys Employee

      The lumped ports don't look to be defined correctly. Please see File>>Open Examples>>HFSS>>Signal Integrity, Connector model. The lumped port should be no wider than the trace width and height extent should be between trace and reference plane. Hope that helps.

    • Liam1

      Thank you slouie for your reply. 

      I found the example, and redefined the ports:



      I think the root of the problem is the radiation boundary.

      With the new ports, if I make the radiation boundary small to touch all the surfaces of the structure, the resonances disappear as well. 

      Any suggestions?



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