RFID technology is easy to miss. It’s invisible, and the components are usually tiny, don’t emit sound, or have a light indicator. RFID also has a wide variety of uses, which is why it’s usually better known as the system or device that incorporates it. Finally, a little-known fact is that its earliest implementation dates back to the 1940s. The early form of this modernized technology was used during the war to prevent friendly fire, track inventory, send instructions, or note the position of vehicles. With that, let’s dive into RFID technology.
Definition of RFID technology
RFID technology, which stands for Radio Frequency Identification technology, is a system consisting of an RFID transponder (a combination of transmitter and responder), antenna, and an RFID reader, also called interrogator and interpreter. The two ends of the system communicate using electromagnetic fields. The connection is initiated by a pulse from an RFID reader, which “interrogates” the RFID transponder, usually a tag or a label. After the data gets back to the reader via the antenna, it automatically uniquely identifies, tracks, and may instruct the transponder to carry simple tasks.
Key features
RFID, besides being a no-contact, wireless way to transfer data over radio waves also has 6 notable features:
- Size. RFID tags can be both large and minuscule. The smallest RFID chip at the time of writing is only 0.05 mm × 0.05 mm.
- Distance. Depending on the size, RFID tags can be read from only a few millimeters to upwards of 100 meters.
- Visibility. Transponders can transfer data without being in the line of sight of the reader.
- Longevity. Unlike bar codes, which can only have properties determined during printing and can never be changed again, RFID tags can be updated digitally, even after the RFID labels are printed.
- Speed. Hundreds of RFID tags can be read simultaneously using a “bulk reading” strategy.
- Versatility. Besides storing data, active RFID tags can act as wireless sensors, for example, monitoring and recording temperature and humidity.
Frequency
The way the RFID system looks and functions is largely determined by the frequency it operates on, and by proxy, the size of the antenna. Here are 4 main frequency bands RFID systems operate in:
- Low-frequency (LF) works in frequency ranges of 120 to 150 kHz, has a slow data transfer, and a short transmission range, about 10 cm or 4 inches. Due to this, this frequency band is unregulated.
- High frequency (HF) operates at a frequency of 13.56 MHz, transfers data at slow to moderate speeds and in ranges of between 10 cm and 1 meter or 4 inches and 3 ft 3 in. It’s part of a radio spectrum named ISM band because it’s exclusive to certain purposes: Industrial, Scientific, Medical.
- Ultra-high frequency (UHF) RFID systems operate at 3 different frequencies:
- 433 MHz. Range of between 1 and 100 meters or 3 to 300 ft at average data speed.
- 865 to 868 MHz in Europe / 902 to 928 MHz in North America. They fall in the same spectrum as HF, but transfer data at average to high speed at distances of 1 to 12 meters or 3 to 40 feet.
- Microwave frequency RFID system operates at 2450 to 5800 MHz and in the ISM band spectrum, the same as Wi-Fi and Bluetooth. It can transmit data at high but in short ranges – 1 to 2 meters or 3 to 7 feet.
Examples of RFID technology
Let’s now turn to a few representatives of RFID technology:
RFID tag
An RFID tag is a common form of transponder that consists of a microchip and an antenna. The chip, as we mentioned, either stores data or performs the tasks the interrogator instructs. There are 3 types of tags, although the first two are used far more frequently:
Passive tag
A passive tag is the cheaper and thus more abundant version. Besides antenna and microchip, it has a substrate – a film made of plastic or Mylar. Its primary purpose is to hold the two other components together, but it also shields radio waves from interference and protects the tag from damage. Because it lacks a power supply, it depends on the power from the RFID reader to act upon instructions, which reduces range.
Active tag
An active RFID tag is the larger, more expensive, and more powerful version. On top of the antenna and microchip, it has 2 more components:
- On-board power supply. Commonly a battery, but can also be a tiny solar panel. It doesn’t depend on the RFID reader’s power, making it capable of sending data or performing tasks independently. This also boosts range considerably.
- On-board electronics. Usually represented by a set of sensors, I/O ports, or microprocessors powered by the built-in power supply.
Semi-passive tag
While semi-passive tags have a power supply, it is minuscule and only sufficient to avoid reliance on the RFID reader’s power. As a result, they can’t use the extra power to boost the range, and only work by modulating the electromagnetic field.
Smart RFID label
A smart label is a way of producing cost-effective RFID transponders or adding new functionality. In its simplest form, it seeks to replace substrate with the conventionally printed 2D label on paper, plastic, or fabric. To ensure consistent positioning, the microchip and antenna are combined with bonding wires, called inlays. They also boost accuracy during automated or bulk reading.
Application of RFID technology
Now you know the basics. Let’s delve into areas where RFID technology applies:
Managing inventory
Passive tags and labels are fastened to many products or parts during manufacturing. This permits the RFID interrogator to bulk scan them in a short period, add them to the database, and keep track of them throughout the process. They also aid during shipping, as they can track dispatching, traveling location, and arriving at the destination when attached to pallets, shipping containers, and packets. Individual products are also frequently protected by tags or labels from theft by customers and employees. If it isn’t removed, the “pylon” at the entrance (an oversized RFID reader, essentially) will start beeping.
Identifying and tracking people
This has multiple uses, but here are two:
- Biometric ID. Also called an e-passport, it uses an RFID chip to store information about the holder. It can include name, date/place of birth, nationality, sex, passport issuance data, and face, iris, and fingerprint scans.
- Access. Tags in the form of labels, bracelets, or access cards can be used to permit access and track people entering a space: workplace, sports event, building, tour bus, etc.