Johanson balun and pcb antenna

RE: Johanson balun and pcb antenna

hakki goceoglu — Tue, 23 Jun 2015 09:30:59 GMT

Thanks a lot, that answers all my questions.

RE: Johanson balun and pcb antenna

Øyvind Karlsen — Tue, 23 Jun 2015 09:10:22 GMT

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

RE: Johanson balun and pcb antenna

hakki goceoglu — Mon, 22 Jun 2015 12:42:23 GMT

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

RE: Johanson balun and pcb antenna

Øyvind Karlsen — Mon, 22 Jun 2015 12:22:12 GMT

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