Radio frequency identification technology(RFID)

Radio frequency identification technology (RFID), is developed in the 1980 s a new automatic identification technology, RFID technology is a use of rf signal through space coupling (alternating magnetic field or electromagnetic field) and transmit information through non-contacting’s message to achieve recognition technology.RFID is a simple wireless system with only two basic components, which are used to control, detect and track objects.The system consists of an interrogator (or reader) and a number of transponders (or labels).

RFID system of RFID system

Automatic identification system composed of radio frequency tag, reader and computer network.Usually, read on an area that form the electromagnetic field, energy is emitted radio tags through read device signal was detected in this area after sending the data stored, read device receives a signal sent by a radio tags, decoding and the accuracy of the calibration data to achieve the purpose of identification.


Initially in the field of technology, transponder refers to the electronic module can transmit information reply information, in recent years, because of rf technology developing rapidly, transponder has a new view and meaning, is known as the smart tag or label.RFID electronic elevator (RFID) reader (reader) wirelessly communicates with RFID electronic tags through the antenna, which can be used to read or write the tag identification code and memory data.A typical reader consists of a high frequency module (sender and receiver), control unit, and reader antenna.

RFID is a non-contact automatic identification technology, it through radio frequency signal automatically identify target objects and access to relevant data, identify work without manual intervention, it can work in all kinds of bad environment.RFID technology can identify high speed moving objects and can recognize multiple labels simultaneously.

Tags: composed of coupled components and chips, each of which has a unique electronic encoding, which is attached to the object to identify the target object.

Reader: device that reads the tag information can be designed for handheld rfid reader (e.g. C5000W) or fixed reader;

Antenna: transmission of rf signals between the label and reader.

Working principle

Label after entering the magnetic field, receive the radio frequency signal from the reader, with the energy gained by the induced current send product information, stored in the chip is passive tags or passive tags), or by the label initiative to send a frequency signal of active tags or active tags, reader reads the information and the decoding, sent to the central information system on data processing.

A complete set of RFID system, is by the Reader and electronic tag is the Transponder and applications of the software system of three parts, its working principle is the Reader to launch a specific frequency radio waves of energy to the Transponder, send the internal data to drive Transponder circuit, the Reader will receive interpreting data in a sequence, for application to do the corresponding processing.

The communication and energy sensing methods of RFID card readers and electronic tags can be divided into two types: inductive coupling and backscattering coupling.Generally, the low frequency RFID adopts the first type, while the higher frequency mostly adopts the second way.

The reader can be read or read/write devices according to the structure and technology used, and is the RFID system information control and processing center.The reader is usually composed of coupling module, transceiver module, control module, and interface unit.The reader and transponder typically use a semi-duplex communication mode to exchange information, while the reader provides energy and timing through coupling to the passive transponder.In practical application, the acquisition, processing and remote transmission of object recognition information can be further realized through Ethernet or WLAN.The transponder is the information carrier of the RFID system. At present, the transponder is mostly composed of the original coupling (coil, microstrip antenna, etc.) and microchip.

Mode of operation

The basic working mode of rfid system is divided into full duplex and semi-duplex system and timing system.The full-duplex indicates that the radio frequency tag and the reader can transmit information to each other at the same time.Half duplex means that the radio frequency tag and the reader can transmit information in both directions, but only send information in one direction at the same time.

In full-duplex and semi-duplex systems, the rf tag response is sent out in the case of electromagnetic fields or electromagnetic waves emitted by the reader.Because compared to the reader itself signal, radio frequency tag signals in the receiving antenna is very weak, so you must use the appropriate transmission method, in order to apply rfid tag signals with the reader.In practice, the commonly used data transmission from the radio frequency tag to the reader load reflection modulation technology to radio tags on the echo of load data into (especially for passive radio frequency tag system).

In contrast, the irradiated electromagnetic fields of the reader are periodically disconnected.These intervals are identified by radio frequency tags and are used to transmit data from rf tags to readers.In fact, this is a typical way of working with radar.The shortcoming of the timing method is that the energy supply of rf labels is interrupted when the reader is sent intermittently, which must be compensated by loading sufficient auxiliary capacitors or auxiliary batteries.