nRF5340 - NFC tag orientation and potential crosstalk

[Gabriele]

Hi,

I’m finishing the design of a nRF5340-based custom board featuring a NFC coil-inductor antenna.
Will orientation of track turns - clockwise or counterclockwise - affect in any way the NFC behavior from the user perspective? Is there a preferred orientation with respect of device's front side ?

The second question is a request for comment about a design choice.
I'm new to NFC design in general and with nRF5340 in particular. I can't know whether antenna induced currents can affect adjacent sensitive signal traces by crosstalk phenomena. Is it a founded concern ? In any case I though it is a good idea to put a small 0-Ohm resistor halfway the coil trace, in such a way I have the chance to open the current loop for the time of SW development. However, if the NFC is already open when disabled, this measure would be unnecessary.

BR,
Gabriele

[Kenneth]

I have never heard this would be a problem, but to be sure we should check with the HW team when they are back from vacation next week. I will keep the case open until then.

Kenneth

[ketiljo]

Orientation of the turns doesn't matter. If you take a normal NFC access card, it will work the same with no regards to the side that faces the reader. You will have the highest reading distance when the size of the reader coil is equal to the tag coil 

As long as the NFC pins are not defined as normal GPIOs when the antenna coil is connected to the pins, there's no risk to harm anything. So you don't need to disconnect the coil when you develop the SW.