Learning Forum

[Liam1]

Hello all,

I am simulating a structure with two lumped ports:

Solution type: terminal

Radiation boundary: a quarter wavelength away from each face

S11:

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]

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:

 

S11:

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?

Best,