What’s UHF, BLE, HF, MiFare… ?

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These days RFID is a pretty wide term applied to all kinds of electronic identity technologies. At a very basic level, RFID tags consist of two primary components; a microchip that processes and stores the information/data and an antenna to receive and transmit RFID radio-wave signals. The first category of “passive” vs “active” depends on how the tag transmits its identity. For passive tags, to read information from the tag/label, a two-way radio-receiver called an interrogator (or reader) sends a radio-wave signal to the tag(s) using its antenna. Tags that are within range of the interrogator’s signal will interrogator’s signal will respond with the data stored in its memory. A majority of RFID tags used in manufacturing and logistics are passive tags, which use the energy from the interrogator’s signal to relay its stored information.

Passive RFID tags primarily operate at three frequency ranges:

Low Frequency (LF) 125  or 134 kHz
High Frequency (HF) 13.56 MHz
Ultra High Frequency (UHF) 856 MHz to 960 MHz, changes depending on region

UHF tags are designed for read over a long range (few meters) vs HF (few centimeters) and LF (few centimeters). Lower frequencies allow better performance near water and metal.

UHF tags are fastest growing market both in terms of revenue and in terms of market adoption due to its ability to read over long range and very low cost. UHF tags follow an ISO standard (ISO 18000-6C) and EPC Gen 2.

There are several HF RFID standards in place, such as the ISO 15693 standard for tracking items,  ISO/IEC 14443 A and ISO/IEC 14443 standards for MIFARE technology, which used in smart cards and proximity cards, and the JIS X 6319-4 for FeliCa, which is a smart card system commonly used in electronic money cards.

Unlike Passive tags, Active RFID tags do not depend on the power transmitted by an interrogator antenna but use a battery to broadcast their identity over radio. Depending on the protocol, there are different types of active RFID tags, each with their advantages and limitations.

433 Mhz band was extremely popular band due to off the shelf availability of radio equipment catering to this band of frequency. However, due to standardization and ubiquity of Wifi and Bluetooth, these tags have become more popular recently. There is one large limitation to using Active RFID tags, battery life. Depending on the size of tag, beacon frequency and some other factors, battery life may range from as little as 3 months to 3 years.

BLE (Bluetooth Low Energy) tags are becoming popular these days due to their cost being substantially more inexpensive than WiFi based tags.


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