Hello,
We have integrated our NFC antenna onto a controller board.
Our antenna measures approximately 90 mm x 40 mm and has 3 turns.
It is already surrounded by ground planes on two sides. The distance between the ground planes and the antenna is approximately 5 mm.
Our PCB manufacturer (of a multi-layer PCB) wants us to fill the antenna area of the inner layers with copper.
Since I found NFC demo boards from NXP where this is implemented in a similar way, I think it should work and would like to implement it similarly.
Are there any reasons why it was implemented this way on these evaluation boards?
To what extent does the copper area affect the range?
Does the copper area affect EMC? Is it better or worse?
What should be the minimum distance between the copper area and the antenna?
Is it better to use a single large area or several small areas?
Thank you very much, and best regards,
Michael
Hello Michael,
The main reason why we use this inner metallization is mainly for a demonstration purpose to simulate a realistic environment around the NFC antenna e.g. in the POS terminal.
Also this metal filling may help to reduce the detuning effect by a different object because the antenna is already tuned with the "metal loading" inside.
However for the real product, I would go for a conventional NFC antenna without any filling inside.
BR
Tomas