CST antenna simulation

[JohnFid]

Hello I am new in CST and I am trying to implement a microstrip antenna.
I want to add a wave guide port on each side of x axis on my structure. Is it right to add these ports on boundaries? What boundaries do I have to choose? On transient solver, must the adaptive mesh refinement be enabled or I have to use the default settings? What type of background material do I have to use (vaccum or pec)?

 

[nschutten]

I haven't worked with CST, but with HFSS and GEMS I got the most representative results when using lumped ports instead of wave ports for microstrip structures.

If you want to simulate antennas, for sure don't use PEC as this will only reflect all radiation from the antenna. You should use an absorbing boundary condition (and the material can indeed be vacuum).

 

[mauloftin]

Hi,
how to use waveguide port with microstrip line you can read in CST help: Contents - CST MICROWAVE STUDIO - Excitation source - Waveguide port overview - Mictrostrip Line.

May be this: https://www.youtube.com/watch?v=k54XWrcI5Bc&list=PL0A63CDCC0D6466C8&index=7

For farfield of antenna you must use "Open (add space)" boundaries.

You can read for example this: https://www.cst.com/Content/Events/...119-PR-WLAN-Microstrip-Patch-Array-Design.pdf

about mesh: 2 cells per substrate height, 2 cells per air gap, 2-4 cells per strip width

Background material is Vacuum of course. (what does it mean antenna in PEC ? )

 

[JohnFid]

Thank you for your answers.
As I've previously said I am new at CST so can you explain what do you mean at about mesh part?

 

[mauloftin]

Try to find answer in the pdf document, page 8. It is about local mesh properties. In the basic tree - "Components" - choose the your mictrostrip and use "right button" on your mouse and choose "Local mesh properties". You can use here "Help" button. You must set it and control mesh.

 

[JohnFid]

Thank you for your answer.
Can you also tell me how to simulate a plane wave and how to set the boundaries for this case?
I uploaded my current project so you can take a look if you want. I used two waveguided port and I want the S parameters from port 1 to port 2.

 

[mauloftin]

Hi,
Sorry I have not experience with plane wave. You want to use plane wave in this case? Why? What si your idea?

So, your project:
1) I think, that the substrate is too small! Must be about min 2xPW (1.6 in your case) on the both site. Not because you are using CST, but it is about how microstrip line works.
2) Your mesh is not good. Try to find answer in the pdf document, page 8. Try find how to use "Mesh Control Fixpoint List" and "Local Mesh". Your mesh is too low in slot.
3) You must read help about waveguide port: CST help: Contents - CST MICROWAVE STUDIO - Excitation source - Waveguide port overview - Mictrostrip Line. You can use Macros - Solver - Ports - Calculate ports extension coefficient. Please pick the metal face before launching macro - it is your patch on the port side.

 

[JohnFid]

I am confused. Can you help me with the fixpoints? I don't know how to use them... :S I have only changed the settings on the global mesh settings.

 

[mauloftin]

Hi, try to use google, for example https://www.google.cz/url?sa=t&rct=...M5O9wYXAvCOtKbw&bvm=bv.47534661,d.Yms&cad=rja

 

[mauloftin]

1) for farfield you do not need plane wave, only waveguide port. Do you know what does farfield mean exactly?
2) Fixpoint list - in version 2013: Home - Mesh view - Fixpoint list (help) - or you can use "Local mesh", but I think, that will be better draw vacuum to the all slot and use local mesh on this slot - follow the attachment