RFID electronic tags are divided into passive, semi-passive (also known as semi-active), and active.

Passive RFID electronic tags
       Passive tags have no internal power supply. Its internal integrated circuit is driven by the received electromagnetic waves, which are emitted by the RFID reader. When the tag receives a signal of sufficient strength, it can send data to the reader. These data include not only the ID number (the globally unique ID), but also the data pre-existing in the EEPROM in the RFID electronic tag.

       Because the passive label has the advantages of low price, small size and no power supply. RFID tags on the market are mainly passive.

Semi-active RFID electronic tag
       Generally speaking, the antenna of a passive tag has two tasks. The first is to receive the electromagnetic waves emitted by the RFID reader to drive the tag IC; the second is that when the tag returns a signal, it needs to be switched by the impedance of the antenna to generate The change between 0 and 1. The problem is that if you want the best return efficiency, the antenna impedance must be designed to be "open and short", which will completely reflect the signal and cannot be received by the tag IC. The semi-active tag is to solve this problem. The semi-active RFID electronic tag is similar to the passive RFID tag, but it has a small battery, and the power can drive the tag IC to make the IC work. The advantage of this is that the antenna can be used as a return signal without taking care of the task of receiving electromagnetic waves. Compared with passive RFID tags, semi-active RFID tags have a faster response speed and better efficiency.

Active RFID electronic tag
       Different from the passive and semi-active types, the active RFID tag itself has an internal power supply to supply the power required by the internal IC to generate external signals. Generally speaking, an active RFID electronic tag has a longer reading distance and a larger memory capacity that can be used to store some additional information sent by the reader.