Johanson balun and pcb antenna

[hakki goceoglu]

Hi All,

I am integrating Johanson's balun and Nordic's L shaped pcb antenna, is it possible to have the antenna connected directly to the balun's pad? as in the below pcb, or do I need an extra track (50Ω) in between. What radio performance should I expect without any antenna tuning?

Thanks in advance, and regards

Hakki

[Øyvind Karlsen]

Hi Hakki,

See this blogpost on General PCB Design guidelines for nRF51. It is possible to connect directly to the baluns pad, but you will get poor performance without antenna tuning. On the design you have provided the antenna is also covered on two sides by a ground plane, this is going to severely affect RF-performance, see the guidelines in l/4 printed monopole antenna for 2.45GHz.

Best regards,

Øyvind

[hakki goceoglu]

Thanks Øyvind,

So as per the design guideline I will add one shunt component for tuning. I do not quite follow you about the ground plane, the design I posted is a copy of Johanson reference design with the pcb antenna added. I did not print the bottom plane at all. Would you clarify this please?

Thanks again and regards

Hakki

[Øyvind Karlsen]

Hi,

Yes, adding one shunt component along with tuning the length of the antenna is the idea. From the picture it looked like the start of the antenna was placed very close to ground, which may lead to bad performance due to high parasitic effects. Best regards, Øyvind

[hakki goceoglu]

Thanks a lot, that answers all my questions.