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I'm creating an app reading NFC tags.

Currently all works well expect that the NFC tag can only be scanned when it touch the back of the phone.

Is there anyway to allow NFC to be read through the screen?

I'm testing on a Nexus 4.

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    You are aware of the fact that the NFC "sensor" usually is integrated in either the back cover or the battery, and that its range is quite limited? With the entire battery in between, I very much doubt you can read tags placed on the "other side". Except they have a QR printed on, and you're using the front camera, that is ;) – Izzy♦ Nov 21 '13 at 22:13
  • I'll just back up what @Izzy said. The range on the NFC scanner used in the Nexus 4 is extremely limited. It's measured in millimeters. Even if the battery, glass, and other electronics didn't impede the signal (Which they do greatly), I don't think that it would be able to read something as far away as the screen. – dotVezz Nov 21 '13 at 22:15
  • Even on best conditions, the specs AFAIK say something about 4 centimeters (for security/privacy reasons), maximum 10 cm (see Wikipedia). And that's with "clear view". The metal components (especially the battery) will shrink that a lot, by at least factor 10 I'd say. That would make for a max of 1 cm, rather less. Now measure the thickness of the device. Guess it's not less than .8 cm. Fat chance for the NFC to pass through. – Izzy♦ Nov 21 '13 at 22:42
  • Is there any Android Phone with better NFC reading range? – Simon Boudrias Nov 21 '13 at 22:51
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    See my answer. With the NFC specs giving a 10 cm range, and the density considerations, that device must be thinner than your finger nail. Speaking of that: Ask Motorola for a tattoo. Not sure if the phone is already included with it ;) – Izzy♦ Nov 21 '13 at 22:58
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With the backing of dotVezz, summing up from the comments:

Considering the specifications, this is quite unlikely:

  • range of the NFC signal is limited to a max of 10 cm on "clear view" (see Wikipedia)
  • material with a greater density will reduce this even more: air ~ 0.001 g/cm3 versus Lithium ~ 0.53 g/cm3 makes rawly a 500-times-density difference, so a factor of 10 (as I mentioned in my comment) probably is a huge under-estimation
  • even calculating with a factor of ~10, this would reduce the range to below 1 cm. And you will rather have to more than double that factor.

With few devices being thinner than .8 mm, your wish is close to impossible of being fulfilled.

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It is possible. Apple has filed a patent on a clever new use of antenna real estate on a smartphone.

Apple patents NFC antenna that works on all sides of a mobile device

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