This is the third post of the Macroelectronics.org RFID series. Stay tuned.
An active RFID is similar to a passive RFID tag: It has similar ciruitry and an antenna to that of a passive RFID. The main difference between the two is that the active version has a battery incorporated to its circuitry. This battery can be the sole or partial source of the tag's power supply.
The advantages of an active RFID include a longer range reading distance. The power supply can amplify the signal and transmit it to farther distances. In addition, the power source to an active RFID can also power other sensors on the RFID, enabling it to send certain signals under certain circumstances.
However, with the RFID, the downside is to replace the battery when the battery is exhausted; Likewise, a serious downfall to an active RFID is its cost. The cost of a single active tag can cost twenty or more USD, which makes buying a couple to several thousand for any use quite pricey. Furthermore, using a battery also leads to a much more bulky RFID, compared to a passive RFID.