Radio-frequency identification

Small tags help us track things.

These tags use radio waves to talk to a reader. A reader sends out a signal. This signal tells the tag to wake up. Then the tag sends back its own number. Some tags have a tiny battery inside. These can talk from far away. Other tags have no battery at all. They get power from the reader's waves. This helps shops find items quickly. It can even help find pets!

These tags are very useful tools.

RFID stands for radio-frequency identification. It is a way to track objects using radio waves.

An RFID system has three main parts. First, there is a tag attached to an object. The tag has a tiny microchip to store data. It also has an antenna to send and receive signals.

Second, there is a reader. The reader sends out a signal to the tag. Third, there is a transmitter to help send data.

Tags can work in different ways. Some are called passive tags. These have no battery. They get their power from the reader's radio waves. Other tags are called active tags. These have a battery inside. Because they have power, they can talk from much farther away.

Many industries use this technology. It helps track cars on a factory line. It can also track medicine in a warehouse. Some people even put tiny chips in pets to identify them.

Unlike a barcode, a reader does not need to see the tag. The tag can be hidden inside an object.

Radio-frequency identification, or RFID, is a clever way to track things automatically.

It uses electromagnetic fields to find and identify objects. This technology is helpful because it can work even if the tag is hidden. Unlike a barcode, a reader does not need to see the tag directly. This means a tag can be tucked inside a box or even an animal.

Many industries use RFID to keep things organized and moving quickly.

An RFID system works using three main parts. First, there is a tiny radio transponder called a tag. The tag has a microchip to store information and an antenna to send signals.

Second, there is a radio reader or interrogator. The reader sends out an electromagnetic pulse to trigger the tag. When the tag feels this pulse, it sends digital data back to the reader.

This data is often a special identification number used for tracking.

There are different ways these tags get their power. Passive tags are small and cheap because they have no battery. They get all their energy from the radio waves sent by the reader. Active tags are different because they have their own battery. This extra power allows them to send signals from much farther away, sometimes up to hundreds of meters.

Some tags are also battery-assisted, meaning they use a small battery to help send their signal back.

The history of this technology goes back many years. In 1945, Leon Theremin invented a device called "The Thing." It was a passive device that used radio waves, making it a predecessor to RFID. In 1973, Mario Cardullo patented a device that was a true ancestor of modern RFID. It was a passive transponder that even had memory.

Later, in 1983, Charles Walton received the first patent using the name RFID. In 1996, others patented a special type of batteryless tag.

Today, RFID is used in many parts of our lives. It can track cars on an assembly line or medicine in a warehouse. Some people even use tiny chips to identify pets or livestock.

The RFID market is huge and continues to grow. In 2014, the market was worth US$8.89 billion. By 2024, about 50 billion tag chips were sold around the world.

Radio-frequency identification, known as RFID, is a method of automatic identification and data capture.

It uses electromagnetic fields to identify and track objects automatically. Unlike a traditional barcode, an RFID tag does not require a direct line of sight to be read. This allows the tag to be embedded deep within an object or hidden from view.

This technology is essential for modern logistics, security, and inventory management across many global industries.

An RFID system relies on the interaction between three main components: a tag, a reader, and a transmitter. The tag is a tiny radio transponder attached to an object. It consists of a microchip, which is an integrated circuit that stores and processes information, and an antenna for signal transmission.

The reader, also called an interrogator, sends out an electromagnetic interrogation pulse. When the tag receives this pulse, it responds by transmitting digital data back to the reader. This data is often a unique identifying number, such as an Electronic Product Code (EPC).

There are three primary types of tags categorized by how they receive power. Passive tags are small and inexpensive because they contain no battery. Instead, they harvest energy directly from the radio waves sent by the reader. However, they require a power level roughly a thousand times stronger than active tags to function.

Active tags include an on-board battery, allowing them to transmit signals over much greater distances, sometimes up to hundreds of meters.

Finally, battery-assisted passive (BAP) tags use a small battery to help power the tag's return signal when it is activated by a reader.

RFID technology has roots in several historical inventions. In 1945, Leon Theremin created "The Thing," a passive listening device that used reflected radio waves. While it was a covert device, its ability to be energized by an outside source makes it a predecessor to RFID. In 1973, Mario Cardullo patented the first true ancestor of modern RFID, which was a passive transponder with memory.

Later that year, researchers at Los Alamos National Laboratory demonstrated reflected-power RFID tags operating at 915 MHz. The first patent specifically using the term "RFID" was granted to Charles Walton in 1983.

Today, the RFID market is a massive global industry. In 2014, the market was valued at US$8.89 billion, growing from US$7.77 billion in 2013. This value is expected to rise from US$12.08 billion in 2020 to US$16.23 billion by 2029. The scale of production is immense; in 2024, approximately 50 billion tag chips were sold worldwide. These tags operate across various frequency bands, ranging from Low Frequency (LF) at 120–150 kHz to ultra-high frequencies used in specialized microwave applications.

Practical applications for RFID are found in nearly every sector. In manufacturing, tags can track an automobile's progress through an assembly line. In healthcare, they can track pharmaceuticals through warehouses. RFID is also used for animal identification through microchips implanted in livestock or pets. In retail, tags help expedite checkouts and prevent theft. However, the ability to read personally linked information has raised significant privacy concerns, leading to the development of new security standards.

Managing multiple tags at once requires advanced technical protocols to prevent data errors. When many tags are in a reader's range, a "collision" can occur if they all respond at once. To solve this, systems use "singulation" methods. One method is the slotted Aloha system, where tags use a pseudo-random delay before responding. Another is the adaptive binary tree protocol, where the reader transmits data bit by bit to identify individual tags.

This ensures that even a pallet full of tagged items can be scanned accurately and efficiently.