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Nov 9 2018

RFID Technology: System, Principle, Classification and Application

Warm hints: This article contains about 3000 words and reading time is about 15 min.


    As one of the key technologies to build the Internet of Things, RFID has attracted much attention because of its long-distance reading and high-storage capacity. It can not only help enterprises to improve the efficiency of controlling goods management and labor cost, but also connect sales and manufacturing enterprises, so that they can receive feedback information and control demand information more accurately, and optimize the entire supply chain. RFID must be widely used in many fields in the future.

Article Core



Introduce RFID 

Article Name

RFID Technology: System, Principle, Classification and Application


Semiconductor Information 


Security Applications,Access Control,Logistics Management,Medical Application


RFID,Reader&Writer,Electronic Tag,antenna   





System Architecture

Electronic Tag 



Reader antenna 

Communication facility 

Antenna Type of RFID 

Operational principle of RFID


Inductive-Coupling RFID System

Back-scatter Coupling RFID System

Characteristicof RFID Technology

Application Field of RFID Technology



        Radio Frequency Identification Technology(RFID), also called electronic tag, wireless radio frequency identification, inductive electronic chip, and non-contact card, is a non-contact automatic identification technology, which can automatically identify the target object and obtain relevant data by radio frequency signal. RFID technology can work in a variety of harsh environments without human intervention. Moreover, it can identify high-speed moving objects and identify multiple tags at the same time, which is fast and convenient to operate. Short-range RF products are not afraid of oil stains, dust pollution and other harsh environments, so that in such environments they can replace barcodes, such as tracking objects on factory assembly lines. Long-distance RF products are mostly used in traffic, which identification distance can reach tens of meters, such as automatic charging or vehicle identification.


         According to the availability of power, RFID is divided into Passive and Active.

  1.Passive Tag : the Passive sensor itself does not have a power supply. Its power supply is generated by a sensor that activated by  emitting frequency from Reader, where the data is finally transmitted back to. The Passive Tag is thin and short and has a long service life but the sensing distance is relative short. 

        2.Active Tag : the price is relative high, volume is larger than Passive tag because of built-in battery. It has longer service life and longer sensing distance.

        According to the frequency, RFID can be divided into three types: LF,HF,UF:

        1.Low Frequency RFID (100~500KHz): low frequency RFID has shorter inductive distance, the reading speed is slower. low frequency RFID of 125KHz is commonly used, whose penetration ability is good.

        2.High Frequency RFID(10~15MHz): high frequency RFID has longer sensing distance, the reading speed is relative high. High frequency RFID of 13.56MHz is the mainly used.

        3.Ultra High Frequency RFID (850~950MHz~2.45GHz):Ultra High Frequency RFID has the longest sensing distance and fastest reading speed, but penetration ability is bad.  

System Architecture 

        According to the function,RFID system can be divided into Edge system and Software system.Edge system mainly completes information perception and belongs to hardware component. Software system completes information processing and application. The communication facility is responsible for the information transmission of the entire RFID system.

System Architecture

Basic composition of RFID system


1.Electronic Tag 

        Electronic Tag also known as the transponder or Smart Label, is a miniature wireless transceiver consisting mainly of built-in antennas and chips.

Electronic Tag  Electronic Tag


        Reader & Writer is a device that captures and processes RFID tag data, either as an individual or embedded in other systems. Reader&Writer is also one of the important components of RFID system, and its name comes from it can write date to RFID. The hardware of the reader is usually composed of transceiver, microprocessor, memory, external sensor / actuator, alarm input / output interface, communication interface and power supply.



Controller is the command center for the orderly operation of the reader chip. Its main functions:

  • Communicate with application system software;

  • Execute the action instructions sent from the application system software;

  • Control the communication process with the tag;

  • Encoding and decoding of baseband signals;

  • Implement anti-collision algorithm;

  • Encrypting and decrypting data transmitted between the reader and the tag;

  • Implement identity authentication between the reader and the electronic tag;

  • Control of other external devices such as keyboards and display devices.

  • Controls operation of the reader chip( the most important). 

4.Reader antenna

        The antenna is a device that receives or radiates the front-end RF signal in the form of electromagnetic waves. It is an interface device between the circuit and the space, which is used to realize the conversion of the guided wave and the free space wave energy. In the RFID system, the antenna is divided into electronic tag antenna and reader antenna, which respectively bear the functions of receiving energy and transmitting energy. The features of the reader antenna are:

  • Small enough to be attached to what is needed

  • Directionality with omnidirectional or hemispherical coverage

  • Capable of providing the chip with the largest possible signal

  • Polarization of the antenna can match the interrogation signal of the card regardless of the direction

  • Robust

  • Cheap price 

5.Communication facility

        Communication facilities provide secure communication connections for different RFID system management and are an important part of RFID systems. Communication facilities include wired or wireless networks and serial communication interfaces for readers and controllers to be connected to a computer. The wireless network can be a personal area network  (such as Bluetooth technology), a local area network (such as 802.11x, WiFi), or a wide area network (such as GPRS, 3G technology), and a satellite communication network (such as a synchronous orbit satellite L-band RFID system).

Antenna Type of RFID 

        RFID has three basic types: coil type, microstrip patch type and dipole type. Among them, the RFID antenna less than 1 meter used by the short distance application system generally adopts the coil type antenna, which has simple process and low cost. It mainly works in the middle and low frequency stage. The RFID antenna of more than 1 meter usually adopts microstrip patch type or dipole type,which is used in the application system. They work in the high frequency and microwave frequency stage. The principles of these antennas are different. 

① Coil Antenna 

        When the RFID coil antenna enters the alternating magnetic field generated by the reader, the interaction between the RFID antenna and the reader antenna is similar to that of the transformer, and the coils of both are equivalent to the primary and secondary coils of the transformer. The resonant loop formed by the coil antenna of the RFID is shown below.

The resonant loop formed by the coil antenna of the RFID 

        It includes the coil inductance L of RFID antenna, parasitic capacitance Cp and parallel capacitor C2, and its resonant frequency is:

    Capacitance C is the parallel equivalent capacitance of Cp and C2. The RFID application system realizes two-way data communication through this frequency carrier. The appearance of ID1 non-contact IC card is small plastic card (85.72mm × 54.03 mm × 0.76 mm), antenna coil resonance frequency is usually 13.56 MHz. A short range RFID application system with minimum area of 0.4mm × 0.4 mm coil antenna has been developed so far.

 coil antenna 

        Some applications require that the RFID antenna coil be small in shape and require a certain working distance, such as the RFID for animal identification. When the antenna coil area is small, the mutual inductance between RFID and reader is obviously not suitable for practical application. Generally, ferrite materials with high magnetic conductivity are inserted into the antenna coil of RFID to increase the mutual inductance and compensate for the decrease of the cross-section of the coil.

②Microstrip antenna 

        Microstrip antenna is an antenna which is fed by microstrip line or coaxial probe on a thin dielectric substrate. On one side, a thin metal layer is attached as a grounding plate, and on the other side, a metal patch with a certain shape is made by photoetching etching method. Microstrip antennas can be divided into 2 types: ①microstrip patch antennas  ② Microstrip slot antenna

  Microstrip antenna

Operational principle of RFID 

        The basic principle of RFID technology: the RF signal to be transmitted by the reader&writer is coded and loaded onto the high frequency carrier signal, and then sent out through the antenna. The electronic label entering the working area of  reader&writer receives the signal. The relevant circuits of the chip in the card perform voltage doubling rectifying, modulating, decoding, deciphering, and then judging the command request, password, authority, etc. Finally, signal processed by tag according to the command.

Operational principle of RFID


        From the point of view of communication and energy sensing between electronic tags and readers, systems can generally be divided into two types, namely, Inductive Coupling system and Electromagnetic Backscatter Coupling system. Inductive coupling is achieved by spatial high-frequency alternating magnetic field, which is based on the law of electromagnetic induction; Electromagnetic back-scattering coupling, that is, the radar principle model: the emitted electromagnetic wave hits the target and then reflects, and carries back the target information, which is based on the law of the electromagnetic wave propagation in space.


2. Inductive-Coupling RFID system 

        The inductive coupling of RFID corresponds to the ISO/IEC 14443 protocol. The inductively coupled electronic tag consists of an electronic data carrier, which usually consists of a single microchip and an antenna made by a large area coil.

        Almost all the tags in inductively coupled mode work passively, and all the energy needed to work on the microchip in the tag is provided by the inductive electromagnetic energy transmitted by the reader. The high frequency strong electromagnetic field is generated by the antenna coil of the reader, which traverses the cross section and surrounding space of the coil to make the nearby electronic tag produce electromagnetic induction.

Working principle Diagram of Inductively coupled RFID system 

Working principle Diagram of Inductively coupled RFID system

3.Back-scatter Coupling RFID System 

① Back-scattering modulation 

        Radar technology provides a theoretical and practical basis for the back-scattering coupling of RFID. When the electromagnetic wave meets a space target, one part of the energy is absorbed by the target and the other part is scattered in various directions with different intensity. In the scattering energy, a small part(echo) reflected back to transmitting antenna and receives by the antenna (so the transmitting antenna is also the receiving antenna). The received signal can be amplified and processed, and the relevant information of the target can be obtained.  In radar technology, this reflected wave can be used to measure the distance and orientation of the target.

        For the RFID system, the electromagnetic back-scattering coupling can be used to transmit the data from the electronic tag to the reader by using the electromagnetic wave reflection. This operating mode is mainly used in systems of 915 MHz,2.45 GNz or higher frequency.

 ②RFID backscattering coupling mode 

        The frequency of a target's reflected electromagnetic wave is determined by its cross section. The cross section is related to a series of parameters, such as the size, shape and material of the target, the wavelength and polarization direction of the electromagnetic wave, etc. Because the reflection performance of the target is usually enhanced with the increase of the frequency, UHF and UHF are used in the RFID backscattering coupling mode, and the distance between the transponder and the reader is more than 1 meter. Readers,electronic tags and antennas constitute a transceiver communication system. 

4.Characteristicof RFID Technology 

① Advantages: 

  • Fast scan: RFID recognizer can read and write multiple RFID tags at the same time, and the reading speed is very fast. The sketch capability of active RFID system can be used for interactive services such as process tracking and maintenance tracking.

  • Miniaturization and variety of shapes: RFID labels develop into miniaturization and variety for different products. The reading of information is not limited by the size and shape of the chip, and it is not necessary to match the fixed size or printing quality of the paper to read accurately. Moreover, the RFID tags are being miniaturized and diversified to be used in different products.

  • The RFID label is to store the data in the chip: The RFID chip and the RFID card reader have a strong resistance to water, oil and chemicals, which is not only free from contamination but also easy to preserve.

  • Reusable: RFID tags repeatedly add, modify, delete the data stored in the RFID volume label, facilitate the update of information.

  • Penetration and unbarrier reading: RFID technology is more accurate than traditional smart chips, and the distance of recognition is more flexible. It can achieve penetration and non-barrier reading. RFID can penetrate materials such as paper, wood and plastics for penetrating communication. It also can read labels though snow, fog, ice, paint, dirt and other harsh environment like bar code can not be used.

  • Large memory capacity: The maximum capacity of RFID is several megabytes, which can be recorded in large quantities. And as technology advances, capacity has increased.

  • Safety: Since RFID carries electronic information, its data content can be protected by passwords, making its content difficult to be forged and altered. 

② Shortcomings:

  • Technological maturity is not enough: RFID technology is new and is not very mature in technology. Due to the reverse reflective nature of UHF RFID tags, it is difficult to apply in metal, liquid and other commodities.

  • High cost: RFID electronic tags are relatively expensive compared to ordinary bar code labels, which are costing dozens of times than ordinary bar code labels. If the usage is large, the cost will be too high, which greatly reduces the enthusiasm of the market for using RFID technology.

  • Technical standards are not uniform: RFID technology has not yet formed a unified standard. Multiple standards coexist in the market resulting in incompatible of different enterprise products. The main manufacturers of RFID systems provide dedicated systems, which lead to different applications and industries adopting frequency and protocol standards of different manufacturers. Incompatible standards have caused confusion in the application of RFID technology, restricting the entire growth of RFID.

③ Prospects:

        In recent ten years, RFID technology has been developed rapidly, and has been widely used in many fields such as industrial automation, commercial automation, traffic control management and so on. With the development of technology, the variety of RFID technology will be more and more abundant, and the application will be more and more extensive. It can be predicted that RFID technology will continue to maintain rapid development in the next few years.

        In general, that current development of RFID tend to be standardized, low cost, low error rate, high security and low power consumption.

  • Standardization: Industry standards and related product standards are not uniform, so far the global electronic label has not formally formed a unified (including each stage) international standards.

  • Low-cost: At present, the lowest price for an electronic tag in the United States is about 20 cents, which cannot be applied to certain low-value individual items. Only when the unit price of an electronic tag drops below 10 cents can it be applied to goods on a large scale.

  • Low error rate: Although the single technology of the RFID tag has matured, the overall product technology is not mature enough, and there is still a high error rate (the rate of RFID misreading is sometimes as high as 20%). In the integrated application, we also need to solve a large number of technical problems.

  • High security:The passive RFID system, which is widely used at present, has no very reliable security mechanism and can not keep the data confidential. The RFID data is vulnerable to attack, mainly because of the RFID chip itself. And chips in the process of reading or writing data are easily used by hackers.

Application Field of RFID Technology

Access Control: personnel access Control Management.

Animal Monitoring: animal management, pet identification, wildlife ecological tracking.

Application Field of RFID Technology

Transportation: toll system for Expressway.

Logistics Management: air baggage identification, inventory and logistics transport management.

Automatic Control:  classification and assembly line management of automobile, home appliance, electronics industry.

Medical Application: management of Medical record system, instrument and equipment in Hospital.

Material Control: automatic inventory and Control system of material in Factory.

Application Field of RFID Technology

Quality Tracking: product quality tracking and feedback.

Resource Recovery: management of stack board, recyclable container.

Security Applications: security management in supermarkets, libraries or bookstores.

Application Field of RFID Technology

Prevention of Counterfeiting: the fight against counterfeiting and counterfeiting of famous brands.

Waste Disposal: garbage collection and disposal, waste control system.

Joint Ticket: smart cards for multi-purpose.

Dangerous Goods: control of ordnance, firearms, detonators and explosives.

 Application Field of RFID Technology


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