Nevertheless, there are also RFID tags getting power
supply by batteries. In this case we can distinguish semipassive
from active RFID tags. In semi-passive RFIDs batteries
power the microchip while receiving the signal from
the reader (the radio is powered with the energy harvested
by the reader signal). Differently, in active RFIDs the battery
powers the transmission of the signal as well. Obviously
the radio coverage is the highest for active tags
even if this is achieved at the expenses of higher production
costs.