By UBK-InfotechRFID Tags: How They Work and Why They Matter
An RFID tag (Radio Frequency Identification tag) is a small electronic device used for storing and transmitting data wirelessly using radio waves. These tags are part of a broader RFID system, which also includes RFID readers and data processing software.
Each RFID tag consists of three primary components:
- Microchip – stores information such as a unique identifier
- Antenna – transmits and receives radio signals
- Substrate – holds the chip and antenna together
There are different types of RFID tags based on power source and frequency range:
- Passive tags (powered by the reader’s signal)
- Active tags (have their own power source)
- Semi-passive tags (battery-assisted but rely on the reader for communication)
How RFID Tags Work
RFID tags operate through the use of radio waves to transmit information from a tag to a reader, enabling wireless identification and tracking of objects, animals, or people. These tags are an essential part of a broader RFID (Radio Frequency Identification) system, which also includes readers and software that processes the data.
The Basic Principle
At the core, an RFID system consists of two main devices:
- The RFID tag, which stores data.
- The RFID reader, which captures that data.
The communication between the tag and the reader happens wirelessly through electromagnetic fields. This process eliminates the need for physical contact or even a direct line of sight, making RFID faster and more versatile than barcode scanning.
How RFID Tags Function
1. The Reader Sends Out a Signal
The process begins when an RFID reader emits a radio frequency signal into the surrounding area. This signal forms an electromagnetic field that "looks" for RFID tags within range.
2. The Tag Responds to the Signal
Each RFID tag has a built-in antenna and microchip.
- The antenna picks up the signal from the reader.
- The microchip holds data, such as a serial number or asset information.
Depending on the type of tag, the method of activation differs:
- Passive RFID tags do not have their own power source. Instead, they draw energy from the reader’s signal to activate the chip.
- Active RFID tags have an internal battery that allows them to broadcast their signal without relying on the reader's power.
- Semi-passive tags have a battery to power the chip but rely on the reader’s signal for communication.
3. Data Transmission to the Reader
Once activated, the RFID tag transmits its stored data back to the reader through radio waves. This data could be anything from a simple ID number to detailed product information.
4. Data Processing and Use
The RFID reader captures the data and sends it to a connected system (often software or a cloud-based database). From there, the information can be used to update inventory, log attendance, track shipments, or control access to secure areas—depending on the application.
How RFID Chips Work
An RFID chip is the brain of an RFID tag. Its role is storing, processing, and transmitting data via radio signals. Though it's tiny—often smaller than a grain of rice—the chip is packed with functionality that enables seamless wireless communication between the tag and an RFID reader.
1. Receiving Power
The first step in the chip's operation depends on the type of RFID tag:
- Passive RFID chips don’t have a battery. Instead, they harvest energy from the electromagnetic field emitted by the RFID reader. When the tag enters this field, the antenna picks up the signal and sends power to the chip.
- Active RFID chips have their own built-in power source (like a small battery), so they’re always ready to transmit data over longer distances.
- Semi-passive chips use a battery to power the chip, but still rely on the reader’s signal for communication.
2. Data Processing and Storage
Once powered, the chip becomes active and begins to function. Inside the chip is non-volatile memory, which stores data like:
- A unique serial number
- Product or asset information
- Sensor data (in advanced tags)
This memory is usually divided into:
- Read-only memory (ROM) – cannot be changed after manufacturing
- Read/write memory – can be updated by authorized systems
- Write-once memory – can be programmed only once
The chip determines how and when this data is shared with a reader.
3. Modulation and Signal Transmission
After retrieving the stored data, the RFID chip encodes this information and sends it back to the reader using a method called modulation. Essentially, modulation alters the radio waves in a specific way so that they carry information.
In passive systems, the chip reflects the reader’s signal in a process called backscatter. This means the chip doesn’t actively send out a signal but manipulates the reflected energy to transmit data.
How RFID Works
A typical RFID system includes:
- RFID tags attached to objects or people
- RFID readers to detect and collect data from the tags
- Middleware/software to interpret and act upon the data
- Database or backend system to store and manage information
Here's an example in a retail store:
- Products are tagged with RFID labels.
- A reader at the exit scans the tags automatically.
- The system updates inventory levels in real time.
- Alarms are triggered if unpaid items are detected.
Unlike barcodes, RFID doesn’t require manual scanning, improving speed, accuracy, and operational efficiency.
Applications of RFID Tags
RFID tags are used in numerous industries due to their versatility:
- Retail: Inventory control, theft prevention, automated checkout
- Healthcare: Patient tracking, equipment monitoring, medication verification
- Logistics: Shipment tracking, warehouse management
- Libraries: Automated check-in/check-out, book tracking
- Access Control: Employee ID cards, event management, building security
These applications showcase how RFID helps reduce human error, save time, and improve visibility across operations.