RFID tags are divided into passive, semi-passive (also known as semi-active) and active.
Passive tags have no internal power source. Its internal integrated circuit is driven by receiving electromagnetic waves emitted by the RFID reader. When the tag receives a signal of sufficient strength, it can send the data to the reader. These data include not only the ID number (globally unique ID), but also the pre-existing data in the EEPROM in the tag.
Because passive tags have the advantages of low price, small size and no power supply. RFID tags on the market are mainly passive.
Generally speaking, the antenna of a passive tag has two tasks. The first is to receive electromagnetic waves from the reader to drive the tag IC. The second type: When the tag returns a signal, it needs to be switched through the impedance of the antenna to produce a 0 to 1 change. The problem is that if you want to get the best return efficiency, it must be "open and short", it will completely reflect the signal, and the tag IC cannot receive it. Semi-active tags are designed to solve this problem. The semi-active type is similar to the passive type, but its battery is small and the power supply can drive the tag IC to work. The advantage of this is that the antenna can be used as a return signal without the task of receiving electromagnetic waves. Compared with the passive type, the semi-active type has a faster response speed and higher efficiency.
Different from the passive and semi-active types, the active tag itself has an internal power source to provide the power required by the internal IC to generate external signals. Generally speaking, active tags have a longer reading distance and larger storage capacity, and can be used to store some other messages sent by the reader.
Radio frequency identification technology includes a complete set of information technology infrastructure, including:
Radio frequency identification tags, also called radio frequency tags and electronic tags, are mainly composed of a large integrated circuit chip with an identification code and a transceiver antenna. They are mainly passive. The electric energy in use comes from the radio wave energy received by the antenna; determine the reading and writing equipment and the corresponding information service system, such as the network of the inventory and sales system.
Comparing radio frequency identification technology with barcode technology, the radio frequency category has many advantages, such as:
It can accommodate more capacity, has a long communication distance, is difficult to replicate, has a high tolerance for environmental changes, and can read multiple tags at the same time. There is a relatively shortcoming that is the high construction cost. However, through the widespread use of this technology, production costs can be greatly reduced.