A complete RFID system consists of reader, electronic tag, so-called transponder and application software system. Its working principle is that the reader emits radio wave energy with a specific frequency, and the driving circuit sends internal data. At this point, the reader sequentially receives the interpreted data and sends it to the application for corresponding processing.
In terms of communication and energy induction between RFID reader and electronic tag, it can be roughly divided into inductive coupling and backscattering coupling. Generally, the first method is used for low-frequency RFID, and the second method is used for high-frequency RFID.
Classification of radio frequency cards:
1, passive RFID.
Among these three types of RFID products, passive RFID is the earliest, the most mature and the most widely used. In passive RFID, the electronic tag receives the microwave signal emitted by the RFID reader, and obtains energy through the electromagnetic induction coil to supply power for a short time, thus completing this information exchange.
2. active RFID.
Active RFID has not risen for a long time, but it has played an indispensable role in various fields, especially in the electronic toll collection system of expressways. Active RFID supplies power through an external power supply and actively sends signals to RFID readers.
3. semi-active RFID.
Passive RFID itself does not supply power, but the effective identification distance is too short. Active RFID identification distance is long enough, but it needs external power supply and is huge. And semi-active RFID is the product of compromise to this contradiction.
Refer to the above content: Baidu Encyclopedia-Radio Frequency Card