Design of a 50 ohms balun on CST

[KacyAma]

Hi everyone

I would like to design a 50 ohms balun on CST and also simulate it. I tried designing one but after simulation it says 'the distance between the element 1 and waveguide port is small. Must be at least three mesh steps'. Advice pls

 

[johnjoe]

First advice: Increase the mesh density
Second advice: Post a pic of your simulation structure. It's easier to help.

 

[KacyAma]

The highest meshcells is 300,000. Where do I increase the mesh density. The attached file is the design of the balun. I just have a feeling the design is wrong. Thank you

 

[johnjoe]

Can you post a better pic of your structure? You can change the mesh density in "Global mesh settings".

 

[KacyAma]

Is this clear enough?

 

[johnjoe]

Ok, increase the mesh density or try to become familar with adaptive meshing and local mesh setup. You can check your settings with the mesh view.

 

[KacyAma]

I will try it. Do you think I should fix another lumped element at the spiral antenna point that is create a point P1 and P2. Because the 50 ohms is feeding into an antenna with an impedance of 183 ohms.

 

[johnjoe]

You're using some coaxial feed for your antenna?

 

[KacyAma]

Yes. But I read somewhere, it was suggested to use a tapered balun for the antenna. I do not know anything about balun or how it is designed. Coaxial balun looked liked the easy one to design.So confused.

 

[johnjoe]

Maybe try for first examination a discrete port.

 

[KacyAma]

Ok I will try it then reply on how it went. Thanks

 

[KacyAma]

@ johnjoe Had to change the design of the balun for a S-band spiral antenna. The issue now is getting the accurate calculation for the design. I am using a journal 'A printed circuit balun for use with spiral antennas' to get the dimension but can't figure it out. Help plssssssss