Brief Introduction of Radio Frequency Technology and Its Application in Library

An RFID Overview

1. Principle of Radio Frequency Identification

Radio Frequency Identification (RFID) is a non-contact automatic identification technology that allows for the automatic recognition and data acquisition from objects, whether stationary or moving. It operates without the need for manual intervention and can function effectively in challenging environments. Unlike traditional barcodes, RFID systems can read information from a distance and do not require line-of-sight, making them ideal for various applications, including library management.

Figure 1: RFID system composition diagram

An RFID system typically consists of three main components: an electronic tag (or transponder), a reader, and an antenna. The electronic tag contains a microchip and an antenna, storing unique identification data. These tags can be affixed or embedded on items to identify them. The antenna serves as a transmitter and receiver, facilitating communication between the tag and the reader. Readers may be integrated with antennas or operate separately, depending on the design. At a minimum, every RFID system must include at least one antenna for signal transmission and reception.

The reader, also referred to as a scanner or reading device, interacts with the tag to retrieve or write data. A standard reader includes a high-frequency module, a control unit, and an antenna. Many readers are equipped with additional interfaces like RS232, RS485, or Ethernet, allowing seamless integration with application systems. The interface between the reader and the system usually includes standardized functions that developers can access via tools like VC++, VB, or PB. These functions typically include:

• 1) Sending configuration commands to the reader as needed by the application system.
• 2) Returning the current configuration status of all possible readers.
• 3) Transmitting various commands from the application system to the reader.
• 4) Providing feedback on the execution results of all possible commands.

When the RFID system is active, the reader emits an RF signal through the antenna. When a tag enters the signal range, it receives energy through spatial coupling and sends back its encoded information. The reader then decodes this data and forwards it to a host computer for processing. This process enables remote data collection, processing, and transmission over a network, supporting automated item identification and information tracking.

2. Classification of RFID Systems

RFID systems are classified based on the frequency used for communication. These include low-frequency (LF), high-frequency (HF), and ultra-high-frequency (UHF) systems. Common operating frequencies are 125kHz, 134.2kHz for LF, and 13.56MHz for HF. Low-frequency tags are cost-effective but have limited data storage and shorter reading ranges. They are often used in applications where shape and flexibility are important. High-frequency tags, on the other hand, can store more data and have longer reading distances, typically ranging from several meters to tens of meters. They are commonly used in card-shaped tags and support high-speed object movement.

RFID systems can also be categorized into active and passive types based on the power source of the tag. Active tags contain a built-in battery, enabling longer reading distances, though their lifespan is limited—usually around 3 to 5 years. Passive tags, however, do not have an internal power source. Instead, they draw energy from the reader’s signal through electromagnetic coupling. These tags use reflection modulation to send data back to the reader, making them more cost-effective and suitable for long-term use.

3. Characteristics of RFID Technology

One of the key advantages of RFID technology is its ability to transmit data through electromagnetic waves, eliminating the need for direct contact or precise alignment between the reader and the tag. This makes RFID highly versatile, capable of functioning in harsh conditions. Tags can be embedded or attached to various shapes and materials, offering flexibility in application. RFID tags can both read and write data, allowing for dynamic updates to stored information. With large storage capacities, they are ideal for complex data management tasks.

RFID systems also employ anti-collision technology to prevent data interference when multiple tags are present. This enables simultaneous processing of numerous tags, with some systems handling up to 50 tags per second. Furthermore, RFID tags are secured with password protection, requiring specialized equipment for access, making them difficult to counterfeit or alter. This enhances the security and reliability of the system, making it a preferred choice for critical applications such as library management.

The Application of RFID in Library Work