RFID short for Radio Frequency Identification, a technology similar in theory to barcode, but is able to provide a wireless, non-contact and non-line-of-sight transfer of data from a tag to its reader , with the use of radio-frequency electromagnetic fields. RFID technology is generally divided into two further categories namely, Passive RFID and Active RFID.
The passive technology is just like your normal door access card system, where you simply unlock a door by tapping a card near a reading device
Passive tags are generally inexpensive, and contains electronically stored data which can be read and decoded using a RFID reader. Passive tags are not equipped with a battery. When these tags are within the vicinity of its readers, they are powered by electromagnetic fields emitted from the reader, enabling them to send data to the readers for processing. The reading distance of the passive technology is generally very limited (typically around 1 to 3 meters), and very susceptible to electromagnetic interference in the environment.
The main difference between Active and Passive technology is that an Active Tag has battery embedded into it and is thus able to broadcast its data to Active Readers even if it is faraway from its readers. A typical reading distance of the Active technology would be 60 meters indoors and 600 meters outdoors. With such a long reading distance, Active RFID systems are suitable to be used for providing real-time location tracking of assets and personnel, or on situations where electromagnetic interference properties like metal, water, or glass are prominent in the environment.
Over the years, industrial needs has caused an evolution to the Active RFID Technology. From a simple tag that controls a function wirelessly like your car-key, it has evolved to enable tracking of the location of the tag, and until to date, sensors can be built onto the tags itself to provide wireless monitoring of temperature, humidity, motion, etc.