The simulation results of cpw structure don't consist with other software

[WEIXUEP]

Hi, i am simulating a impedance matching structure using palace, this structure transforms impedance from 5 Ohm to 50 Ohm. However, a phase shift was observed when compared with other software (FEM of HFSS, MoM of Cadence).

The structure is as follows (Substrate er=3.66, tanD=0.004, H=0.508mm):

A similar model is created in HFSS:

The simulation results are:

I am not sure if this issue arises from the json configuration or the mesh. I tried changing some of the modeling settings, or using a denser mesh, but it had little effect.

The simulation results of HFSS and PALCE (s2p):
results.s2p.tar.gz

Port-S file (csv):
port-S_P1.csv
port-S_P2.csv

Mesh file and json file:
mesh_json.zip

HFSS Project:
20241230_PALACE_HFSS.aedt.zip

[WEIXUEP]

Besides, i set "CrackDisplacementFactor" : 0.0 (issue #319)

[hughcars]

Hello @WEIXUEP,

I lack access to an HFSS license, so am unable to inspect those HFSS files in any meaningful way. That plot doesn't immediately convince me that there is a bug however, but suggests there is likely some other divergence between your configuration and those of the HFSS model. The Palace results look reasonable, despite not being identical to HFSS and Cadence.

Have you checked they are identical problem setups? I am assuming that no amr is being performed in hfss or cadence.

1. Is the external boundary condition identical? Palace is using a first order absorbing boundary condition, what is the external boundary condition in HFSS?
2. What is the scale in that plot? You are saying "similar" model created in HFSS, suggesting it's not identical, in that the mesh generated within HFSS and that used with Palace (generated with gmsh it looks like?) then you could very easily get different results as you will not be fully resolved. I'm not aware of a way to pass meshes between HFSS and external systems.
3. Have you done a refinement study? Refining the mesh and/or increasing the polynomial order, do you arrive at a converged solution between the three systems
4. What does the HFSS mesh look like compared to the mesh used in Palace?