Electronic – DIY NFC boosting antenna for a mobile device

androidantennanfcrfid

I am very new to this. I'm a dentist trying to improve client flow in a busy office.

I would like to develop a cheap proof of concept for an NFC enabled client tracking system using a hacked mobile phone. My idea is to develop a system where I place passive NFC tags on the door frames of my office. As a client walks into the room, the cell phone reads the NFC tag and sends a message via Wi-Fi to a computer which collects the data.

Since NFC only works at short distances, I would like to make an external antenna that would extend the range of the cell phone (Samsung Galaxy 4) and allow it to read tags at a distance of about 30-60 cm. The size/shape of the antenna is not a concern at this point, but practically speaking the largest dipole antenna I would consider is 200 cm. (I'm not completely sure what a dipole antenna is but I read this and it sounded important 🙂

I know RFID is better at these distances but it's also more expensive and I'd like to keep the cost to the absolute minimum. The same goes for the mobile device. This may be possible with more specialized equipment but the cost and ubiquity of mobile phones make it the preferred reader (also makes programming the tags easier).

My questions are:

  • Is this feasible?
  • How would the antennas be designed? Shape – planar circular vs cylindrical vs dipole; Size – 22.11 meters long
  • What is the best way to connect to the native NFC antenna pins?

Best Answer

When I first read your question I assumed the following:

  • You are trying to track your clients' movements using your clients' smartphones
  • Your clients would have to install an app on their smartphones in order to enable this

Then I saw the discussion about hacking the smartphones to change their antennas. This would imply that you would be providing the phones and giving them to the clients.

Hacking a cellphone to make it read NFC at a greater distance, would IMHO be quite a difficult task. As has been pointed out, NFC is specifically designed to limit distance (for privacy and security considerations, I believe).

Unless I'm missing something... if your scheme requires giving them something to carry with them in the clinic, you might just as well give them RFID tags, and place RFID readers in the doorways.

On the other hand, if you want to use the clients' cellphones with a downloaded app, as another poster suggested, Bluetooth low energy beacons might be a better approach, as BLE is designed to be readable at a greater distance.

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