Only making cards tells you what RFID (electronic tags) are.

Only cards are madeTell You What RFID (Electronic Tag) Is

1. What is an electronic tag?

Electronic tags are also known as RFID tags or RFID (RFID). It is a non-contact automatic identification technology that uses radio frequency signals to identify target objects and obtain related data. The identification process requires no manual intervention. As the wireless version of barcodes, RFID technology offers advantages that barcodes do not have, such as waterproofing, magnetic resistance, high temperature resistance, long service life, long reading distance, encrypted data on tags, larger storage capacity, and flexible changes in stored information.

2. What is RFID?

RFID stands for Radio Frequency Identification. It is commonly referred to as an inductive electronic chip or proximity card, contactless card, electronic tag, electronic barcode, and so on.
A complete RFID system consists of two parts: the Reader and the Transponder. The operating principle is that the Reader emits infinite radio wave energy at a specific frequency to the Transponder, driving the Transponder circuit to send out the internal ID code, which the Reader then receives. Transponder's uniqueness lies in its battery-free, contactless, and card-free design, making it resistant to dirt. Its chip password is unique worldwide and cannot be duplicated, offering high security and long lifespan.
RFID has a wide range of applications. Typical applications include animal chips, automotive chip anti-theft devices, access control, parking lot control, production line automation, and material management. There are two types of RFID tags: active tags and passive tags.

3. Classification of electronic tag technology

1. Working Methods
 
The basic operating modes of RFID systems are divided into Full Duplex, Half Duplex, and Sequential (SEQ) systems. Full-duplex means that the RFID tag and the reader/writer can transmit information to each other at the same time. Half-duplex means that information can be transmitted bidirectionally between the RFID tag and the reader/writer, but only in one direction at a given time.
In full-duplex and half-duplex systems, the RF tag's response is transmitted in the form of electromagnetic fields or waves emitted by the reader/writer. Because compared to the signal from the reader itself, the RF tag's signal is very weak on the receiving antenna, it is necessary to use appropriate transmission methods to distinguish the signal from the reader's signal. In practice, data transmission from RFID tags to readers generally uses load reflection modulation technology to load RFID tag data onto reflected echoes (especially for passive RFID tag systems).
The timing method is the opposite, where the electromagnetic field emitted by the reader is periodically disconnected for short periods. These gaps are identified by RFID tags and used for data transmission from the RFID tag to the reader. In fact, this is a typical radar operating method. The drawback of the timing method is that during reader transmission intervals, the energy supply to the RF tag is interrupted, which must be compensated by installing sufficiently large auxiliary capacitors or auxiliary batteries.

2. Data volume
The data volume of RFID RFID tags typically ranges from a few bytes to several thousand bytes. However, there is one exception: the 1-bit RF tag. It only needs 1 bit of data to allow the reader to make two judgments: "There is an RF tag in the electromagnetic field" or "No RF tag in the electromagnetic field." This requirement is fully sufficient to implement simple monitoring or signal transmission functions. Because a 1-bit RFID tag does not require an electronic chip, the cost of the RFID tag can be made very low. For this reason, a large number of 1-bit RFID tags are used in department stores and stores for anti-theft systems (EAS). When leaving a department store with unpaid goods, readers installed at the exit can identify the situation of "radio frequency tags in the electromagnetic field" and trigger corresponding reactions. For goods that have been paid for according to regulations, the 1-bit RFID tag is removed or deactivated at the checkout.

3. Programmable

Whether data can be written to RFID tags is another factor distinguishing RFID systems. For simple RFID systems, the data on RFID tags is mostly a simple (sequential) number that can be integrated during chip processing and cannot be changed later. In contrast, writable RFID tags write data through readers or dedicated programming devices.
Data writing on RFID tags is generally divided into two forms: wireless writing and wired writing. Currently, the RF tags used in locomotives and freight cars in railway applications all use wired writing methods. 

4. Data carriers
To store data, three main methods are used: EEPROM, FRAM, and SRAM. For general RFID systems, using Erasable Programmable Read-Only Memory (EEPROM) is the main method. However, the drawbacks of this method are that it consumes a lot of power during the write process, and its lifespan is generally 100,000 write cycles. Recently, some manufacturers have also started using so-called ferroelectric random access memory (FRAM). Compared to erasable programmable read-only memory, ferroelectric random access memory reduces write power consumption by 100 times and writes by even 1000 times. However, due to issues in production, ferroelectric random access storage has not yet been widely adopted. FRAM belongs to the non-volatile class of storage.
For microwave systems, static random access memory (SRAM) is also used, which can quickly write data. To permanently preserve data, an auxiliary battery is needed for uninterrupted power supply.

5. State Mode
For programmable RF tags, the "internal logic" of the data carrier must control the write/read operations on the tag memory and the authorization requests for write/read authorization. In the simplest case, a state machine can accomplish this. Using a state machine allows for very complex processes. However, the drawback of state machines is the lack of flexibility in modifying programming functions, which means designing new chips requires modifying circuits on silicon chips, making design changes costly.
The use of microprocessors has significantly improved this situation. During chip manufacturing, the operating system used to manage application data is integrated into the microprocessor via masking, with minimal modification. Additionally, the software can be adjusted to suit various specialized applications.
Additionally, there are RFID tags that store data using various physical effects, including read-only surface wave (SAW) RFID tags and 1-bit RFID tags that can usually be deactivated (write "0") and rarely reactivated (write "1") by 1-bit RF tags. 
6. Energy supply
An important feature of the RFID system is the power supply of the RFID tag. Passive RF tags have no power supply themselves. Therefore, all the energy used for the operation of passive RFID tags must be obtained from the electromagnetic field emitted by the reader. In contrast, active RF tags contain a battery that provides all or part of the energy (the "auxiliary battery") for the microchip's operation.

7. Frequency range
Another important feature of RFID systems is their operating frequency and reading distance. It can be said that the operating frequency is closely related to reading distance, which is determined by the propagation characteristics of electromagnetic waves. The operating frequency of an RFID system is usually defined as the frequency at which the reader sends the RF signal when reading the RFID tag. In most cases, this is called the reader transmission frequency (load modulation, backscatter). In any case, the "transmit power" of RF tags is much lower than that of readers.
The frequencies sent by RFID system readers generally fall into three ranges:
(1) Low frequency (30kHz ~ 300kHz);
(2) Mid-high frequency (3MHz ~ 30MHz);
(3) Ultra-high frequency (300MHz ~ 3GHz) or microwave (>3GHz).
Based on the range of action, additional classifications of RFID systems are: tightly coupled (0 ~ 1 cm), remote coupling (0 ~ 1 m), and long-distance systems (> 1 m).
 
8. RF tags → data transmission to readers and writers
There are various ways for RF tags to send data back to the reader, which can be summarized into three categories:
(1) Use load modulation for reflection or backscattering (the frequency of the reflected wave matches the frequency of the reader's transmission);
(2) Using the reader's transmission frequency subharmonics to transmit tag information (the tag's reflected waves differ from the reader's transmission frequency, representing higher harmonics (n times) or subharmonics (1/n));
(3) Other forms.

4. RFID applications are quite broad
1. Logistics: Cargo tracking during the logistics process, automatic information collection, warehousing applications, port applications, postal services, express delivery
2. Retail: Real-time statistics of product sales data, restocking, and theft prevention
3. Manufacturing: Real-time monitoring of production data, quality tracking, and automated production
4. Apparel industry: automated production, warehouse management, brand management, single product management, channel management
5. Medical: medical device management, patient identification, infant theft prevention
6. Identity verification: various electronic documents such as electronic passports, ID cards, and student IDs.

7. Anti-counterfeiting: Anti-counterfeiting of valuables (cigarettes, alcohol, medicines), anti-counterfeiting of tickets, etc

8. Asset Management: Various types of assets (valuable, large quantities, highly similar items, or hazardous materials, etc.)
9. Transportation: non-stop highways, taxi management, bus hub management, railway locomotive identification, etc
10. Food: Manage the preservation of fruits, vegetables, fresh produce, and food
11. Animal identification: Identification and management of trained animals, livestock animals, pets, etc
12. Library: Used in bookstores, libraries, publishers, etc
13. Automobiles: manufacturing, anti-theft, positioning, car keys
14. Aviation: manufacturing, passenger tickets, luggage and parcel tracking
15. Military: Identify and track ammunition, firearms, supplies, personnel, trucks, and more

Detailed RFID Reference Materials:http://www.zhizuoka.com/mod_article-article_content-article_id-238.html