wlcsp
Full Member level 3
Did anybody ever simulate symmetric structure (e.g. CPW, microstrip) in HFSS 9.2 ? It is really ridiculous, the S11 is not the same as S22. Any comment on this?
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wlcsp said:Did anybody ever simulate symmetric structure (e.g. CPW, microstrip) in HFSS 9.2 ? It is really ridiculous, the S11 is not the same as S22. Any comment on this?
Wiley said:S11 and S22 will not be equal unless the mesh is also symmetric. Since HFSS uses adaptive meshing, the mesh will almost certainly not be symmetric. FDTD codes uses a cartesian gridding; by its very nature this gridding is symmetric.
However, S11 and S22 should be very close. If they are not close, I suspect you have an error in your setup.
wlcsp said:Wiley said:S11 and S22 will not be equal unless the mesh is also symmetric. Since HFSS uses adaptive meshing, the mesh will almost certainly not be symmetric. FDTD codes uses a cartesian gridding; by its very nature this gridding is symmetric.
However, S11 and S22 should be very close. If they are not close, I suspect you have an error in your setup.
I agree with you, I also thought about it. My result shows less than 1 dB difference. However, I was wondering where the HFSS start to generate the mesh. Is there any trick to make the mesh symmetric?
Kit-the-great said:I see no way to make it. But the difference between parameters, that must be equal, indicates the value of simulation error. If You have the difference about 0.1 dB - this indicates that the simulation error not less than 0.1 dB. In this case I'm usually replace both parameters by its simple average. Usually this procedure slightly decrease the error and restore the structure symmetry.
Best regards,
Kit