question about NFC and Bluetooth antenna

[Cindy]

Hi 

I'm really new to this filed and don't know anything about antenna, please forget me if the question is stupid. 

I have an nRF52 DK, I noticed the Bluetooth antenna on it is PCB antenna,  so my question is 

1) if I have to design my own, will it be hard or I can do the same on the development board?

2) or keep the same circuit design in the development board, but add an attached antenna, what specifications should I follow to pick the antenna?

And I know the NFC antenna on nRF 52 DK is not commercialized, so how do I find a replacement? 

(we want to use NFC to do some cellphone authentication, like between a cellphone and nRF52, so the distance will be close, like 3-5cm, but inside a plastic enclosure)

Any suggestion will be helpful.

Thanks

Cindy

[Heidi-Irene Harvey Sollie]

Hi Cindy!

I recommend reading this blog post regarding general PCB design guidelines for the nRF52 series.

Specifically the section entitled "Antenna" is relevant to your question. You can choose between using a PCB antenna and a chip antenna (consider that the PCB antenna is cheaper as it is one less component), and if you choose PCB antenna there is a white paper called Quarterwave printed monopole antenna for 2.4GHz that explains how to design it.

Regarding the NFC antenna, the schematic for Nordic's NFC antenna is available on our website here in the download section under nRF52-DK hardware files and I have also attached it below. So, the easiest would just be to use this design and produce your own.

Note that you can send your PCB files to us for review before production. Just create a private ticket and attach the relevant files.

I hope this answers your questions!

Best regards,
Heidi

PCA64110_Schematic_And_PCB.pdf

[Cindy]

Hi Heidi

Thanks for your reply, I checked the PCA64110_Schematic_And_PCB.pdf file you attached, it's like a printed picture of the NFC antenna, there's no dimension or anything. I still don't know how to design my own, would you mind explain it a little more?

I never designed an antenna, so I just add the antenna on my pcb board top or bottom layer and don't cover it copper pour? 

[Heidi-Irene Harvey Sollie]

Hi, I just linked the pdf as an example. Here is the folder with all hardware files, including the Altium files.

nRF52 Development Kit - Hardware files 1_2_1.zip

[Cindy]

Hi 

can I just get an external NFC antenna? would any of them work? or it has to a specific one? or any specifications I should look for?

[Heidi-Irene Harvey Sollie]

Hi, yes you can also buy an external NFC antenna from a third party provider. All of them should work right out of the box, just make sure the frequency is 13.56 MHz. 

The other thing to consider is that the size and shape of an NFC antenna should be roughly the same size and shape as the reader you're gonna use it with, to achieve maximum power transfer. For example the antennas on Nordic's development kits have roughly the same size and shape as the NFC Forum Reference Antenna Poller 6, which works with most NFC readers. 

The NFC Forum sets these specifications, so you could also take a look at their website for more information.

Best regards,

Heidi