What is RFID? A Basic Guide to Radio Frequency Identification

What is RFID? Radio Frequency Identification (RFID) is a technology that uses a radio wave to identify an object. The main components of an RFID inlay include the IC (integrated chip) which executes commands and stores data; the antenna which absorbs RF waves and helps broadcast the signal; and the substrate which is the material that the chip and antenna are attached to.

There are different types of RFID tags. Active RFID tags are battery powered and typically larger in size. These tags ping a continuous signal so they are always “on.” Because of this the battery and tag has a shorter lifespan than either passive or battery assist tags. There are numerous advantages to active RFID tags including longer read ranges and larger memory; however, this also comes at a higher cost than the other categories of tags.

Unlike active RFID tags, passive RFID tags do not have a battery. They obtain their power from the electromagnetic field created by the reader. In other words, the reader turns them “on” when they are within read distance. Because they do not have a battery they will last longer than active RFID tags and they are also a less expensive option. Passive tags typically have a shorter read range than either active or battery assist tags; however, read ranges depend heavily on the tag, reader and the material the tag is attached to.

Battery assist or semi-active RFID tags have a battery to operate the chip’s circuitry; however, they communicate similarly to passive tags in that the reader activates the tags. Battery assist tags have a greater read range than passive tags. They are less costly than active tags and more expensive than passive RFID tags.

RFID tags come in different frequencies including low frequency (LF), high frequency (HF) and ultra-high frequency (UHF). Low-frequency tags operate at 125 kHz while high-frequency tags operate at 13.56 MHz and are typically used to identify items in close proximity. High-frequency tags also allow greater user memory access and are a good choice for security applications. Ultra-high frequency tags operate at 860-960 MHz (Class 1, Gen 2) which is a worldwide frequency and are typically used in supply chain and asset control applications. UHF tags usually have a challenge with liquids and metals; however, this can be easily overcome with either the use of a specialized inlay or an isolator as a standoff.

There are many advantages to using RFID in comparison to other auto-ID technologies. A primary advantage is the ability to read a large number of items in a short period of time – greatly improving efficiency. Another advantage is the fact that you do not need to have a line of sight in order to read the tags as well as the ability to have a longer read range in comparison to other technologies like bar code.

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