Active RFID vs. Passive RFID

Active RFID and Passive RFID are fundamentally different technologies that are often evaluated together. While both use radio frequency energy to communicate between a tag and a reader, the method of powering the tags is different. Active RFID uses an internal power source (battery) within the tag to continuously power the tag and its RF communication circuitry, whereas Passive RFID relies on RF energy transferred from the reader to the tag to power the tag.  

The active tag is battery-powered and always, well, active. It is consistently on the lookout for a reader’s signal.

The passive tag relies on energy transferred from a reader to power up and transfer its information.

  Passive RFID requires stronger signals from the reader, and the signal strength returned from the tag is constrained to very low levels. Active RFID allows very low power RF beacons to be received by the reader because the reader does not need to power the tag for the tag to respond. Additionally, the Active RFID tag is continuously powered, whether in the vicinity of the reader or not. Active tags can also “beacon” or initiate communication with a reader (or other tags) when certain conditions are present. Active tags can contain external sensors to monitor temperature, humidity, motion, and other conditions.

Active tags can contain sensors to monitor conditions such as…

Temperature

Humidity

Motion

See the table below for a direct comparison of the two technologies.

	Active RFID	Passive RFID
Power	Battery operated	No internal power
Required Signal Strength	Low	High
Communication Range	Long range (100m+)	Short range (3m)
Range Data Storage	Large read/write data (128kb)	Small read/write data (128b)
Per Tag Cost	Generally, $15 to $100	Generally, $0.15 to $5.00
Tag Size	Varies depending on application	“Sticker” to credit card size
Fixed Infrastructure Costs	Lower – cheaper interrogators	Higher – fixed readers
Per Asset Variable Costs	Higher – see tag cost	Lower – see tag cost
Best Area of Use	High volume assets moving within designated areas (“4 walls”) in random and dynamic systems	High volume assets moving through fixed choke points in definable, uniform systems
Industries/Applications	Auto dealerships, Auto Manufacturing, Hospitals – asset tracking, Construction, Mining, Laboratories, Remote monitoring, IT asset management	Supply chain, High volume manufacturing, Libraries/book stores, Pharmaceuticals, Passports, Electronic tolls, Item level tracking

   Source : http://atlasrfid.com/auto-id-education/active-vs-passive-rfid/