Now that the repeater stickers are available, I think it would be a good place to start documenting the best placement of the stickers on the devices that we have available to us. I will try to keep the same and similar format as the wiki-nfc-phone-performance topic. You can use the Xfd or Diagnostic Card to find the best placement. For those that do not have access to these tools this can be a refference point.
This resource is a good starting point on figuring where to zero in your repeater
When using the diagnostic card or circular field detectors to find the best placement, are you simply looking for where the fiend field is strongest (e.g. the LED is brightest)?
Or are you using the repeater and the detector at the same time to find a place where the detector lights up with the repeater, but wouldn’t without it?
For anyone who got the new Pixel 9 Pro Fold and the official case, the sweet spot for the repeater stickers is right on top of the Google logo (on the official case)
Google publishes a hardware diagram for all Pixel phones, including my Pixel 7a, showing you the exact location of the NFC chip. Interestingly, for the Pixel 9 Pro Fold they display the chip a bit higher than the sweet spot shown above.
I also have a new Motorola Moto G15 Power. The manual puts the NFC chip to the right of the bottom two camera lenses:
So quite often you can find the location somewhere on the manufacturer’s website. If not, you can also roughly pinpoint the location using a small NFC tag (I used a coin tag), a piece of paper and a marker. Tape the paper to the back of the phone and try the tag in various locations, marking where it did or did not work. If you cover the whole backside and connect all the spots where the tag was detected by the phone, it should be somewhere in the middle of that. I initially used that method before I found the official locations, and it corresponded quite closely.
Great advise @robm i have found that usually the field is strongest at the corners of where the antenna bends. at least when devices are placed directly close to the coil. This is also a good point of refference for people that just want to at a glance find their device and see the best spot.
