How does a passive NFC tag work
NFC technology is pretty common in most high-end smartphones. As well as phone to phone communication, NFC tags can also be used to store and transfer information. You will probably have noticed small NFC tags next to advertisements near bus stops, stickers in shops, or may have even come across the clever idea of using NFC enabled business cards.
The NFC tags can store wide ranges of information, such as a web address or contact details, to links to apps in some Stores. It’s a quick and efficient way to quickly push information to your phone and NFC tags can replace bar and QR codes, and could even be used instead of Bluetooth in some cases.
How it works?NFC tags are passive devices, which means that they operate without a power supply of their own and are reliant on an active device to come into range before they are activated. The trade-off here is that these devices can’t really do any processing of their own, instead they are simply used to transfer information to an active device, such as a phone or PAD.
In order to power these NFC tags, electromagnetic induction is used to create a current in the passive device. the basic principle is that coils of wire can be used to produce electromagnetic waves, which can then be picked up and turned back into current by a another coil of wire. This is very similar to the techniques used for wireless charging technologies.The active devices are responsible for generating the magnetic field. This is done with a simple coil of wire, which produces magnetic fields perpendicular to the flow of the alternating current in the wire.
NFC tag induction circuit and the tiny microchip on the back of a NFC sticker tag.The passive device works in the same way, just in reverse. There is always some power lost during transmission through the air, but over short distances the current generated is enough to power the circuitry in the NFC tag.
These circuits are fine tuned to a certain frequency, which increases the device’s sensitivity to charging frequencies. This allows for a maximum transfer of energy across the air. Once the tag is powered up, it can sync up and send data over the 13.56MHz NFC transmission frequency at either 106, 212 or 424 Kbps, just like your regular NFC communication between phones or other larger devices.
There are a range of different tag types available, each offering different storage levels and transfer speeds. just only 106 kbit/s. Although that may sound quite small, but that’s enough data for some very simple pieces of information, These tags are designed to be highly cost effective, and can also be re-used if you want to change the data stored on them.
NFC tag is Cheap and effective,over other forms of short range wireless communication, is that tags are incredibly cheap to make and maintain, but can still be used for a wide range of applications. With very simply circuitry and very few components, NFC tags can be produced on mass for very low unit costs.
Combine low costs with the absence of any power requirements, and you have a cheap yet effective way of quickly communicating with other smart devices. From launching applications, to exchanging web addresses and purchasing a rail ticket, NFC aims to make our lives that little bit more convenient just by using our smartphones.
Given the roll-out of mobile payment methods than can use NFC, more and more smartphones are shipping NFC communication enabled. Don’t be surprised if you see more and more of these little tags popping up all over the place..
If you want to pick up some good tags for a project or just to mess around with, there are usually some pretty good deals available over at www.sertag.com