This blog post explores how the RFID technology hidden in transportation cards works and how diversely it is utilized in our daily lives.
We primarily use public transportation when moving around the city. Each time, we pay using a transit card, and the technology enabling the transit card reader to deduct money from our card is RFID (radio frequency identification). Thanks to this technology, we can conveniently use public transportation, yet we often don’t understand its underlying principle. This article explores the principles of RFID technology and its applications.
To understand RFID, we must first understand electromagnetic induction. Electromagnetic induction refers to the phenomenon where a potential difference occurs in a conductor placed within a changing magnetic field. For example, if the strength of a magnetic field passing through a circular wire changes, an induced current occurs. The faster the magnetic field strength changes, the stronger the induced current in the wire. This electromagnetic induction phenomenon was theoretically established through the research of Michael Faraday and James Clerk Maxwell and is applied in various electronic devices and technologies today.
Now, using the above principle, let’s explain transportation cards that utilize RFID. RFID, also known as radio frequency identification, is a recognition system that reads stored data from tags, labels, cards, etc., embedded with semiconductor chips, wirelessly and contactlessly using radio frequencies. An RFID system typically consists of a tag, a reader, and a host. There are several types of tags. The most basic are passive tags and active tags. Passive tags, like those used in transit cards, lack a separate battery and must receive power from the reader. Active tags, on the other hand, can generate their own power, enabling the tag and reader to exchange information.
In a transit card system, the tag refers to the transit card itself, the reader is the point where the card is tapped, and the host is the central computer where the information is stored. The transit card contains a circular conductor pattern inside the plastic card, along with an embedded IC chip and antenna. This IC chip stores information such as the card’s balance and the user’s age. Therefore, this chip is the core component of the RFID system.
Now, let’s look at how RFID works. When you tap your card on the reader while boarding a bus or subway, the antenna in the reader continuously emits radio waves. When the card receives these waves, the IC chip transmits the information stored within it (such as the amount of credit, transfer status, etc.) to the antenna in the tag. The antenna then sends this information to the reader. The crucial question here is how a passive tag like a transit card receives power. Since RFID relies on wireless recognition, how does it obtain power to transmit data?
In reality, RFID doesn’t receive power directly but generates it itself. The reader emits not only radio waves but also a consistent magnetic field. When the card is brought close, the magnetic field strength passing through the card’s conductor increases. This process induces electromagnetic induction, causing an induced current to flow. This induced current is then used to transmit wireless radio waves back to the reader. This is a prime example of how the principle of electromagnetic induction, mentioned earlier, is applied in RFID.
The same process occurs when exiting public transportation, and the remaining balance after payment for the trip is stored on the transit card. The reader records the amount we paid, and later, the amounts recorded by each reader are aggregated on the host system to settle the actual total.
RFID technology is utilized not only in transit cards but across various aspects of our lives. For example, smartphone payment systems use NFC (Near Field Communication), an application of RFID technology. This technology allows us to make payments conveniently without a wallet. NFC is one of the application technologies of RFID that enables data transmission over short distances. It is widely used due to its convenience and efficiency.
Furthermore, RFID technology plays a crucial role in the logistics industry. For instance, active tags, used for recording and tracking logistics information, are attached to various goods, enabling real-time monitoring of their location and status. This has significantly enhanced logistics management efficiency and is widely utilized, particularly in large retailers and warehouse management systems.
In conclusion, RFID is a technology that innovatively transforms our lives based on a simple principle. Though it involves invisible small tags and radio waves, this technology plays an essential role in various fields, including the public transportation systems we use daily, logistics, and payment systems. RFID technology is expected to advance further, providing even greater convenience to our lives.
