Principle of NFC tags?

Time：2016/3/30 17:18:34    

NFC (near field principle of wireless communication technology, the key lies in the "near-field", its use is the inductance of the mutual coupling, the basic principle of equivalent of a transformer. If the main open some RFID card, and then you find there have a coil, the coil is actually is the inductance of the secondary coil. NFC by evolution of RFID technology, RFID principle is this: the RFID card and the card reader each have an inductance coil, we put the RFID card close to the corresponding card reader, card reader inside the inductance coupling coil on the one hand, ACTS as the role of the transformer primary winding, powering a passive RFID identification card, RFID card inductor is equivalent to the secondary coil of the transformer, on the other hand in the RFID card chip information stored by its internal modulation on the coil of the RFID card (its modulation principle is a regular change inductance coil impedance to regular primary coil load), the RFID card reader by testing its internal impedance change law of inductance coil.