Radio Frequency Identification
Radio Frequency Identification (RFID) systems have recently garnered interest in the field of electronics. These are convenient and comparatively low-cost systems which have been used in many fields such as retail business, medical industry, and supply chain management.
RFID systems consist of a Radio Frequency (RF) tag reader, typically consisting of a transmitter/receiver module connected to an antenna; and mobile RF tags, typically consisting of a low-functionality microchip connected to an antenna. More generally, an RFID system consists of a tag reader and a number of tags that are packaged to the objects that need to be tracked or identified.
The tag reader communicates with tags via an RF link. The frequency range of the transmission between the reader and the tag is from 3 GHz to 30 GHz .The reader then transmits the information stored on the tags to a computer system. The most common method for reading passive tags at close range is called inductive coupling: the coiled antenna of the reader produces a magnetic filed with the coiled antenna of the tags. The tags obtain the energy form this field and use it to send their ID back to the reader.
Every tag contains a unique identification code. In addition, the tag stores a great deal of information, such as a customer’s account number. There are three types of RFID tags: active tags, passive tags, and semi-passive tags. They are classified by the type of power support used. The active tag needs a battery to provide its power. Tags of this kind can be read from 100feet away so they are usually applied to track expensive items over long ranges. On the other hand, the passive tag is an RFID tag that does not use a battery. When the RF link from the tag reader reaches the chip’s antenna, a magnetic field will be created between the reader and the antenna. Once the magnetic field has provided power to the passive tag, the tag can send to the reader whatever information is stored on the tag’s chip. Generally, the passive tag is less expensive than the active tag. However, the passive tag is limited to short-distance communication.
Currently, there are some interesting and important issues concerning the RFID technology, such as the security, data privacy and collision.