By Jeff Polly | December 12, 2014

Radio frequency identification (RFID) technology has become much more common across a number of industries, but there are a variety of different types of RFID technology, tags, and readers — each uniquely suited to different types of applications.

RFID tags can be classified by the radio frequency range they use to communicate (low, high, or ultra-high), and the way the tag communicates with the reader (active or passive). Listed below are the different types of RFID technology, their capabilities and limitations, and the types of applications for which they are best suited.

What’s the Frequency?

RFID tags can be grouped into three categories based on the range of frequencies they use to communicate data: low frequency (LF), high frequency (HF) and ultra-high frequency (UHF). Generally speaking, the lower the frequency of the RFID system, the shorter the read range and slower the data read rate.

Low Frequency (LF) RFID: These RFID systems operate in the 30 KHz to 300 KHz range, and have a read range of up to 10 cm. While they have a shorter read range and slower data read rate than other technologies, they perform better in the presence of metal or liquids (which can interfere with other types of RFID tag transmissions). Common standards for LF RFID include ISO 14223 and ISO/IEC 18000-2. LF tags are used in access control, livestock tracking, and other applications where a short read range is acceptable.

High Frequency (HF) RFID: HF systems operate in the 3 MHz to 30 MHz range and provide reading distances of 10 cm to 1 m. Common applications include electronic ticketing and payment and data transfer. Near Field Communication (NFC) technology is based on HF RFID and has been used for payment cards and hotel key card applications. Other types of smart card and proximity card payment and security systems also use HF technology. Standards include ISO 15693, ECMA-340, ISO/IEC 18092 (for NFC), ISO/IEC 14443A and ISO/IEC 14443 (for MIFARE and other smart card solutions).

Ultra-High Frequency (UHF) RFID: These systems have a frequency range between 300 MHz and 3 GHz, offer read ranges up to 12 m, and have faster data transfer rates. They are more sensitive to interference from metals, liquids, and electromagnetic signals, but new design innovations have helped mitigate some of these problems.

UHF tags are much cheaper to manufacture, and as such are commonly used in retail inventory tracking, pharmaceutical anti-counterfeiting, and other applications where large volumes of tags are required. The EPCglobal Gen2/ISO 18000-6C standard is a well-known global standard for item-level tracking applications.

Check out real-world examples of UHF RFID applications and ROI with our application brief on Returnable Container tracking or our white paper “Returnable Container Tracking: Challenges, Benefits and Financial Impact.”

Passive or Active?

There are two other common classifications of tags, depending on how the tag communicates with the reader: passive or active.

Active RFID: Active RFID tags have their own transmitter and power source (usually a battery) onboard the tag. These are mostly UHF solutions, and read ranges can extend up to 100 m in some instances. Active tags are usually larger and more expensive than their passive counterparts and are used to track large assets (like cargo containers, vehicles, and machines). Active RFID tags are also often equipped with sensors that measure and transmit temperature, humidity, light, and shock/vibration data for the objects they are attached to.

There are two types of active tags. Transponders only “wake up” and transmit data when they receive a radio signal from a reader. For example, a transponder attached to a vehicle in a toll payment or checkpoint control location would only be active when passing through a particular gate. This helps conserve battery life.

Beacons, on the other hand, emit a signal at a pre-set interval. This type of active tag is used in real-time location systems (RTLS) for tracking anything from wheelchairs at a hospital to large cargo containers at a shipping dock.

Passive RFID:  In passive RFID solutions, the reader and reader antenna send a signal to the tag, and that signal is used to power on the tag and reflect energy back to the reader. There are passive LF, HF, and UHF systems. Read ranges are shorter than with active tags and are limited by the power of the radio signal reflected back to the reader (commonly referred to as tag backscatter).

Passive tags are usually smaller, less expensive, and more flexible than active tags. This means they can be attached or even embedded on a wider variety of objects. Passive UHF tags are commonly used for item-level tracking of consumer goods and pharmaceuticals, for example.

Battery-Assisted Passive (BAP) RFID: A third, hybrid type of RFID tag has also emerged. BAP systems, or semi-passive RFID systems, incorporate a power source into a passive tag configuration. The power source helps ensure that all of the captured energy from the reader can be used to reflect the signal, which improves read distance and data transfer rates. Unlike active RFID transponders, BAP tags do not have their own transmitters.

By matching the right type of RFID tag to your application, you can ensure a successful deployment and reap the full benefits of the technology. The different types of RFID technology allow you to get creative to solve real-world business problems. Make sure you get the most out of your RFID solution by downloading our whitepaper “Are You Realizing the Full Benefits of RFID?”


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