An RFID reader is able to read/write data from/on an RFID tag by using radio signals. In logistics processes RFID gates are often used to read tagged items.

The information is stored on the RFID chip of the RFID tag.

Passive RFID tags

Passive RFID tags contain no battery, and are often in the form of a shipping label. The read distance of passive tags is less than 10 meters. The read range of the passive tag is typically limited by the radio power from the reader required to power the tag integrated circuit.  If the circuit wakes up, the sensitivity of the RFID reader is typically sufficient to detect the response from the tag. The price of label type passive tags is typically around 0.1-0.2 EUR.

A passive UHF RFID label format tag.

A harsh condition resistant passive UHF RFID tag.

Semi-passive RFID tags (Battery Assisted Passive tags, BAP)

The integrated circuit of a semi-passive (BAP) tag gets its power from the battery. Therefore they do not use the usual 90% of incoming radio power for operation, but only about 15% of it. The reflected signal is therefore stronger than for a passive tag. BAP tags still communicate passively with the reader (by modulating the backscatter of the reader radio signal). Typically the read range is more than 20m. BAP tags are considerably cheaper than active tags: price range is around 1-5 EUR.

Active RFID tags

Active RFID tags contain transmitter and battery and are bigger and more expensive than passive one-way tags. The read range of active tags is more than 30 meters, although they are limited in battery lifetime. Active tag prices range typically around 20EUR.