RFID 101
For those of you that are new to this technology, RFID ("radio frequency identification") is a method of identifying unique items using radio waves without human intervention. An RFID system typically consists of:
RFID reader - A device used to communicate with RFID tags. The reader has one or more antennas, which emit radio waves and receive signals back from the tag. The reader is also sometimes called an interrogator because it "interrogates" the tag.
RFID antenna – A device attached to the RFID reader that is used to emit radio waves. The RF energy from the reader antenna is used to power up the microchip on the tag, which then reflects back its own signals.
RFID tag – This object consists of a microchip attached to an antenna (conductive element on the tag) that is packaged in a way that it can be applied to an object. The tag picks up signals from and sends signals to a reader via the reader antenna. The tag contains a unique serial number, but may have other information, such as a customers' account number. Tags come in many forms, such smart labels that can have a barcode printed on it, or the tag can simply be mounted inside a carton or embedded in plastic.
There are three main types of RFID:
Passive RFID – the RFID tag does not have a power source. The chip on the tag is powered up when it passes through an RF field and sends its data back to the reader via backscatter. The three most common frequencies are:
o Ultra High Frequency (UHF) operates at 915 MHz. This typically offer better range (20-30 ft) and can transfer data faster than LF and HF tags, but they use more power and are less likely to pass through materials.
o High Frequency (HF) operates at 13.56 MHz. This is for solutions that require read distances of less than two feet. HF works better on objects made of metal or have a high water content.
o Low Frequency (LF) operates at 125 kHz. These use less power and are better able to penetrate non-metallic substances and items with high liquid content but their read range is limited to less than a foot.
NOTE: Battery assisted passive (BAP) RFID tags require an external source to wake them up but uses this power to greatly increase the read range
Active RFID – the RFID tag does have its own power source. These tags can transmit signals autonomously and can be read over 100+ feet.
RTLS - similar to Active RFID in that the tag does have its own power source. The main difference is that RTLS (Real Time Locationing System) uses a wireless network infrastructure instead of readers and antennas.
