topic Re: PN7642 Antenna Design in NFC

PN7642 Antenna Design

MPEngineering — Wed, 02 Jul 2025 19:39:32 GMT

Hey there,

i´m currently designing an custom PCB with PN7642 and i wanted to ask, if somebody has experience with the minimum size of a custom antenna.

The PCB is quite small. The problem i see is, that if underneath the antenna is a solid GND or VCC plane, much power dissipates into it, right? In that case the size would be about 37 x 12 mm.

The size with plane free area for the antenna could only be 17,25 x 9,5 mm.

Could this be enough?

Best regards

Oliver

Re: PN7642 Antenna Design

KaiLi — Thu, 03 Jul 2025 02:29:33 GMT

Hello @MPEngineering

It's recommanded that you try online NFC Antenna Tool NFC - NXP Community to design antenna according to your application Scenario.

For pcb layout, please check PN76 family antenna design guide, especially 3.3 section.

Re: PN7642 Antenna Design

MPEngineering — Thu, 03 Jul 2025 10:44:55 GMT

Hey KaiLi,

thanks for replying. I know this Guide, but there is nothing about the Shape for the Antenna itself, only recommendations for routing the BGA.

I´ve read in the "PN7160 antenna design and matching guide", that the smaller the antenna, the smaller the reading distance.

But what is meant with small? Or is it try and error princip?

Re: PN7642 Antenna Design

KaiLi — Fri, 04 Jul 2025 00:19:06 GMT

Hello @MPEngineering

"Small" means small in size. Please refer to Figure 2 in Chapter 2.1 of PN76 family antenna design guide

The shape and size of the antenna depend on your application requirements. You can also use the NXP recommended design. For the PN7642, the antenna can be square with a size of 45*45mm.