nRF52 Antenna Design Questions

[billt79]

Hi,

I need to design a small nRF52 board, with a 3cm by 3cm size. I am very new to antenna design, so i have some questions, in order to avoid ruining it. The reference PCB antenna on the nRF52 dev kit will be too big, so i was wondering if i could modify it, or move to a chip antenna. I would rather use the PCB antenna than a chip if it can be helped due to costs. Firstly i was wondering if the lobe itself could be mirrored so it faces in the other direction, which will save some space, and also i was wondering about the rf connecter aswell, and how to remove it, without changing the impedance or resonance. It also has a ground plane underneath the connector on the top layer, so i would like to know how to remove the plane and the connector. Will it just be ok to bridge it with the same size of track and remove the plane? Also i was wondering about the size of the keepout layer, if the PCB is going to be smaller than the width of the keepout, will it matter as long as the width is the same size? My main worry is that the ground plane will be too small. Also for extra info, i am looking for a range of around 10 metres, ideally with a low transmit power. The device will be worn around the wrist, which may also be a factor. Thanks in advance for your help and time.

[Anders Strand]

Hey.

Download the reference layout for our nRF51 Dongle. On that we use a smaller "meander" antenna.

When designing wearable products, try to place the antenna in such a way that the radio waves do not have to travel though body tissue. This will reduce your signal strength.

-Anders

[billt79]

Thanks Anders, We don't really have the funds for the hardware in order to tune a new antenna design, which is why we prefer to use existing designs, however in this case we will have to do our own. We don't require optimal range, and nor will it require certification, so we will have to rely on trial and error unfortunately. Thanks for the advice, but i do have one further question, what is the purpose of C15 on the nRF52 DK antenna? I know the chances of use getting a decent antenna from trial and error are slim, but i will just have to make do with what i can get.