Designing Balun using CST for plnar yagi antenna

[andrion]

Does anyone know how to design a Balun for planar yagi antenna? I would like to know how to calculate each component using TXline calculator. Please help me. thanks

 

[Marco_A_Llamas]

Hi, you need to pass from a umbalanced mode to a balanced one. The balum will depend on the acces TL do you have. Are you looking for CPW-to-Slotline transition?


marco

 

[andrion]

Yes, I am doing that one.
Actually, I have finished my desgin and when I do it practically, the PCB technician told me that the gap in my Balun design is quite small. So, I need to improved my design without changing the result. DO u have any ideas?

Hi, you need to pass from a umbalanced mode to a balanced one. The balum will depend on the acces TL do you have. Are you looking for CPW-to-Slotline transition?


marco

 

[Marco_A_Llamas]

Hi,

You can maintain your CPW even mode impedance just redesigning central conductor and slots width. Unfortunatly this is more complicated for your slotline mode as this mode impedance will depend mainly on the slotline gap and your substrate properties (if slotline strips are thinner they can also impact the slotline impedance). In my opinion a reasonable approach is:

1- Ask to the lab technician for the minimun spacing between metals.

2- design your slotline that connects to your antenna taking into account previous lab technician recomendation.

3- Extract your slotline impedance

4- design your CPW even mode that match your slotline impedance and It is compatible with spacing bwetween metals.

I can recommend you a IEEE paper in case you have access to it. I wrote it few years ago. It's about wideband CPW to sloline transitions

M.A. Llamas, D. Girbau, M. Ribó, L. Pradell, “Compact, Wideband CPW-to-Slotline Multimodal Transition”, European Microwave Conference, pp. 897-900, Munich, Germany, 8-12 October 2007

Let me know if you require more assistance.

BR

Marco