The basic components of an RFID system are:
- Host computer with appropriate application software
RFID tags are tiny microchips with memory and an antenna coil, thinner than paper and some only 0.3mm across. RFID tags listen for a radio signal sent by a RFID reader. When a RFID tag receives a query, it responds by transmitting its unique ID code and other data back to the reader. There are two types of RFID tags—passive and active.
RFID readers, also called interrogators query RFID tags in order to obtain identification, location, and other information about the device or product the tag is embedded in. The RF energy from the reader antenna is collected by the RFID tag antenna and used to power up the microchip. There are two types of RFID readers:
- RFID read-only readers: As the name suggests, these devices can only query or read information from a nearby RFID tag. These readers are found in fixed, stationery applications as well as portable, handheld varieties.
- RFID read-write readers: Also known as encoders, these devices read and also write (change) information in an RFID tag. Such RFID encoders can be used to program information into a "blank" RFID tag. A common application is to combine such a RFID reader with a barcode printer to print "smart labels". Smart labels contain a UPC bar code on the front with an RFID tag embedded on the back.
There are 4 major frequency ranges that RFID systems operate at.
- Low Frequency (LF) 125 to 148 KHz
- High Frequency (HF) 13.56 MHz
- Ultra High Frequency (UHF) 915 MHz
- Microwave 2.45 GHz
Generally, low-frequency systems are distinguished by short reading ranges, slow read speeds, and lower cost. Higher-frequency RFID systems are used where longer read ranges and fast reading speeds are required, such as for vehicle tracking and automated toll collection. Microwave requires the use of active RFID tags.