RFID tags are divided into passive, semi-passive (also called semi-active), and active.
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 tag.
Because the passive label has the advantages of low price, small size and no power supply. RFID tags in the market are mainly passive.
Generally speaking, the antenna of a passive tag has two tasks. The first is to receive electromagnetic waves emitted by the reader to drive the tag IC; second: when the tag returns a signal, it needs to be switched by the impedance of the antenna to generate 0 Change with 1. The problem is that if you want the best return efficiency, the antenna impedance must be designed in "open circuit and short circuit", 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 type is similar to the passive type, 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 the passive type, the semi-active type has a faster response speed and better efficiency.
Different from the passive and semi-active types, the active tag itself has an internal power supply to supply the power required by the internal IC to generate external signals. Generally speaking, active tags have a longer reading distance and a larger memory capacity that can be used to store some additional messages sent by the reader.
Radio frequency identification technology includes a complete set of information technology infrastructure, including:
Radio frequency identification tags, also known as radio frequency tags and electronic tags, are mainly composed of large-scale integrated circuit chips with identification codes and transceiver antennas. They are mainly passive. The electrical energy when in use is taken from the radio wave energy received by the antenna; Identify the reading and writing equipment and the corresponding information service system, such as the networking 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 hold more capacity, has a long communication distance, is difficult to copy, 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 cost of construction. However, through the extensive use of this technology, production costs can be greatly reduced.