For a passive tag, the induced current has to be sufficient to generate the power necessary to activate the chip as well as to transmit the response to the reader. Consequently, passive RFID systems are limited to short read ranges (between reader and tag) on the order of 30 cm to 3 m, depending on the system’s frequency band (as discussed later). The obvious advantage of active RFID systems is that they can operate over greater distances and do not require reception of a signal from the reader’s antenna to get activated. However, active tags are significantly more expensive to fabricate than their passive cousins.