This article explains how the transportation cards we use every day work and the RFID technology used in them. It will cover how RFID uses electromagnetic induction to transmit data contactlessly and is used in a variety of fields, including public transportation, as well as logistics and payment systems.
We often use public transportation to move around the city. We pay for each trip with a transit card, and the transit card reader uses a technology called radio frequency identification (RFID) to read our money from the transit card. This technology makes it easy for us to use public transportation, but we often don’t know much about how it works. In this article, we’ll explain how RFID technology works and its applications.
To understand RFID, we first need to know about electromagnetic induction. Electromagnetic induction is the phenomenon where a potential difference is created in a conductor in a place where the magnetic field changes. For example, when the strength of the magnetic field passing through the circular wire we are talking about changes, a current is induced. In this case, the faster the magnetic field passing through the wire changes, the higher the current induced in the wire. This phenomenon of electromagnetic induction was theorized through the work of Michael Faraday and James Maxwell, and is applied to various electronic devices and technologies today.
Now, let’s use the above principle to explain how transportation cards use RFID. RFID, also known as radio identification, is an identification system that uses radio frequencies to contactlessly read stored data from tags, labels, cards, etc. that have embedded semiconductor chips. An RFID system typically consists of a tag, a reader, and a host, of which there are several types of tags. The most basic are passive tags and active tags. Passive tags, such as those found in transportation cards, do not have a separate battery and need to be powered by the reader. Active tags, on the other hand, can generate their own power, allowing the tag and reader to exchange information.
In a transportation card system, the tag is the transportation card, the reader is where the transportation card is swiped, and the host is the central computer where the information is stored. A transportation card is a plastic card with circular wires inside that contains an IC chip and an antenna. This IC chip contains information about how much money is on the card, how old the cardholder is, and so on. This chip is the heart of the RFID system.
Now, let’s take a look at how RFID works. When you take the bus or subway, you hold your card up to the reader, and the antenna on the reader continuously emits radio waves. When the card receives these radio waves, the IC chip transmits the information embedded in the chip (how much money is charged, whether you’re transferring, etc.) to the antenna on the tag, which sends the information to the reader. An important point to note here is how the transit card, which is a passive tag, is powered. RFID is wireless, so how can it be powered to transmit data?
In fact, RFID doesn’t receive power directly, but it does generate it. The reader generates not only radio waves, but also a constant magnetic field, and when you bring the card close to it, the magnetic field that passes through the card’s wires becomes stronger. This creates electromagnetic induction, which in turn creates an induced current, which is used to transmit radio waves to the reader. This is a good example of how the principle of electromagnetic induction we mentioned at the beginning of this article works in RFID.
The same process happens when we get off public transportation, and our transit card stores the balance after we pay for the trip. The reader records the amount we paid, and later the host sums up the amounts recorded by each reader and settles the actual amount.
RFID technology is used in many areas of our lives, not just transportation cards. For example, payment systems using smartphones use Near Field Communication (NFC), an application of RFID technology. This technology allows us to make payments without the need for a wallet. NFC is one of the applications of RFID that can transmit and receive data over short distances and is widely used due to its convenience and efficiency.
RFID technology also plays an important role in the logistics industry. For example, active tags, which are used to record and track logistics information, are attached to various goods, allowing the location and status of goods to be monitored in real time. This has greatly improved the efficiency of logistics management and is widely used, especially by large retailers and warehouse management systems.
In conclusion, RFID is a technology that is revolutionizing our lives based on a simple principle. Although it is a small tag and radio waves that are invisible to the eye, this technology plays an essential role in the public transportation systems we use every day, as well as in logistics, payment systems, and many other areas. In the future, RFID technology will continue to evolve and bring even greater convenience to our lives.
