HFSS GS simulation

[Meow_Qin]

Hi, I have some problems when simulating Ground(G)-Signal(S) structure transmission line using HFSS. Below is the model. As for the GSG coplanar waveguide structure, the waveport should intersect both of the ground signals to define the signal electrode. My model only has one ground electrode and one signal electrode and the structure is symmetrical. I need to calculate the S parameter, characteristic impedance and effective indices of the two ports. The waveports are set according to the slotline port with an integration line marked in the picture. However the results are wrong. I want to know how to set the waveports correctly. Many thanks!

 

[PlanarMetamaterials]

Welcome, Meow_Qin

You haven't highlighted the wave ports, but I'm guessing one is that tall rectangle.
The aspect ratio looks off, it's probably too tall and you might be exciting higher-order modes. Please show us the modes that are being excited on the ports.

 

[30 dBw Basho]

Ditto on the fact that the first port is likely too long and skinny.

I'd reduce the size of it, and also make sure you're putting a radiation boundary on the outside of the sol'n region, and checking the "Use Radiation Boundary on Ports" option under the advanced tab of your sol'n setup.