Radio Frequency Identification (RFID) technology allows communication using electromagnetic fields. To achieve this, an RFID system must have an RFID tag and an RFID reader.
Different types of RFID tags have varying features tailor-made for specific functions. This article analyzes all the types of RFID tags available in the market and advises on the best pick for various applications.
What is an RFID Tag?
An RFID tag comprises an integrated circuit, an antenna, and a substrate. The integrated circuit has a microchip that stores and processes data.
The antenna receives and transmits signals. Once the tag is close to an RFID reader, the RFID tag’s antenna detects the electromagnetic waves and releases the data stored in its memory.
Types of RFID Tags
RFID tags are classified based on the radio wave frequency used. The three wavelengths used include:
- Ultra-High Frequency (UHF)
- High Frequency (HF)
- Low Frequency (LF)
Each of the frequencies gives the RFID tag special applications. For example, an LF tag is ideal for livestock tracking while an HF tag is commonly used for access control.
Low-Frequency RFID Tags
LF band ranges between 30 kHz and 300 kHz. However, low-frequency RFID tags are only allowed to operate within a range of 125 kHz to 134 kHz. They have wavelengths of up to 2400 meters
Despite this long wavelength, LF tags have a shorter read range of a few centimeters (a maximum of 50 cm). This limitation is attributable to their dependence on magnetic coupling.
Nevertheless, its large wavelength gives them an advantage. The LF waves can easily penetrate metal and water making them highly efficient for use on liquid-based items and livestock.
Additionally, these tags are relatively durable. They come in different sizes and shapes to suit your needs. As such, you can be sure of ease of customization and modification for guaranteed efficacy and convenience.
Disadvantages of LF RFID Tags
While the tags are highly efficient in tracking livestock, they have several limitations, including:
- They are Costly. LF RFID tags are more expensive than HF tags. The cost ranges between $0.5 and $20 per tag.
- Slow Read Rates. LF tags have very low data transmission speed. As such, it takes relatively longer for the RFID reader to receive and decode message signals from the tag.
- Lack of Security Standards. LF RFID tags lack adequate security standards. As such, you should avoid using them where data encryption is required.
LF antenna and RFID readers are available in different forms. This diversity allows you to choose the best antenna/reader combination based on your needs and your budget. On average, an ideal combination will cost you a few hundreds to a thousand dollars.
High-Frequency RFID Tags
HF RFID tags operate within a range of 3 MHz and 30 MHz. The HF wavelength is shorter than that of the low-frequency tag (approximately 22 meters).
Just like LF tags, the HF RFID tags use magnetic coupling to send and receive signals. The waves can penetrate most materials except water and other dense materials.
They have a read range of up to one meter. As such, these tags are ideal for ticketing, access control, and use on smart passports.
Within the high-frequency band used by RFID tags is the Near Field Communication (NFC) technology that operates on a single frequency of 13.56 MHz. Just like RFID tags, NFC tags use radio waves to communicate and exchange data – a communication protocol that is recognized and approved by ISO under the ISO 14443 & ISO 18000-3 standard.
While HF bands can also operate in moist areas, they are not as effective as LF tags. As such, it is not the best for use in tracking livestock and other moist items. However, HF tags are highly effective in ticketing, payment systems, access controls, and data transfer systems.
The use of HF standards is regulated by various standards including ISO 15693 for tracking, ISO/IEC 14443 standards for MIFARE technology, and ISO/IEC 14443 A for proximity cards & smart cards.
One of the striking disadvantages of the HF RFID tag is the fact that its signals can be affected by materials such as liquid or metal.
Ultra-High Frequency RFID Tags
Ultra-High Frequency (UHF) tags operate within a radio frequency spectrum of 300 MHz to 3 GHz. However, most tags are designed to operate on frequencies between 860 MHz and 960 MHz with only a few operating at 433 MHz and 2.45 GHz.
UHF RFID systems are highly regulated and many countries/regions have formulated regulations and standards to guide their operations. If these regulations did not exist, the efficacy of UHF RFID tags would be affected due to:
- Device Interference with Each Other. UHF devices can easily interfere with each other leading to inoperable status or very poor operations.
- Widespread use of UHF tags would lead to differing signaling standards which would affect their operation adversely.
Unlike HF and LF systems, UHF does not communicate using magnetic coupling as stipulated by GS1 EPCglobal UHF Class 1 Gen 2 standards under ISO 18000 6C standard.
UHF tags communicate at approximately 33 centimeters or 12 centimeters for higher frequencies such as 2.45 GHz tags. Additionally, UHF comes in two different types:
- Passive UHF RFID System. This system uses passive backscatter modulation and has no additional power source. As such, they rely on power from UHF RFID readers which limits the read range to a maximum of 30 meters. Additionally, most passive UHF tags cost as low as $0.1 cents a tag, which explains their widespread use in race timing, laundry management, tool tracking, and asset tracking. However, these tags are sensitive to liquids and metals.
- Active UHF RFID Systems. This system does not rely on a backscatter transmission system but rather an internal battery for power. The tags are proactive and send beacons at given intervals to announce their presence. When active RFID readers detect these beams, they pass them to a controller for processing. Active UHF tags have a long read range that can span more than 100 meters. Additionally, UHF tags can be customized to withstand harsh environments and extreme temperatures.