Coplanar Waveguide - How to set up ports?

Fatih Yüksekkaya_21211

Hello community,

I am currently working on a simulation involving a coplanar waveguide (CPW) in FEKO. The structure consists of a signal trace flanked by two ground planes. I’ve set up the geometry and boundary conditions, but I’m unsure if I’ve defined the ports correctly. There was an example online that I followed, but the fields don’t appear as I’d expect for a coplanar waveguide. Specifically, the electric field distribution doesn’t show the expected behavior for a quasi-TEM mode.

Here’s what I’ve done so far:

1. Defined the CPW geometry with the correct signal and ground trace dimensions.
2. Used an edge port to excite the signal trace relative to the ground planes.
3. Specified the port width and height, but I’m not sure if they align correctly with the structure.
4. Ran the simulation and visualized the near fields, which seem off compared to typical CPW field profiles.

My port is set up as following: A small rectangle extending back to the large ground plane connection (edge port).

This is the field line I get from this simulation:

I have attached my model for better analysis. My specific questions are:

1. Is my port definition correct?
2. Is there any other way I could use besides an edge port? (e.g. microstrip port)
3. If the ports are defined correctly, why do the field lines look not as expected from a CPW?
4. Off-topic: Is there any way to a have a finite thickness microstrip line? I would like to simulate the traces with a thickness of 35µm but would the edge port definition still work the same way for that? Or would I need a FEM simulation for that and then set up a FEM line port?

Thank you in advance!

Best regards

Fatih

Jaehoon

Hello Fatih,

I can't find your model.

However, please see the following pages "A-2.2 How to Feed a Grounded Coplanar Waveguide" in the Feko user guide. You can get some idea to construct the port.

Regards,

Jaehoon