Attaching tags to wild animals, for
instance, makes it possible to track them. For such reasons, the RFID system has been
spotlighted as the technology that can replace bar code systems.
Tags can be classi?¬?ed into two types based on the existence of self-electric power: active tags
and passive tags. The active tags can transmit data without the aid of a reader because it has its
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own battery. They also have a more powerfulmemory than passive tags. On the other hand, it
is possible for a passive tag to transmit onlywhen a reader is involved since it does not support
self-electric power. Passive tags have constraints in functionality, but they have distinct
advantages over active tags. They are small enough to attach to an object easily, and they do
not need to consider power consumption due to its dependency on the reader??™s power. Inthis
chapter, the focus of consideration is to the passive tags. An RFID reader sends out a signal
supplying power for tags. The tag extracts energy from the electromagnetic ?¬?eld by charging
its capacitor until it is able to operate. When it is charged, communication between the reader
and the tag is possible, that is why passive tags can operate without their own battery.
An RFID reader communicates with tags through radio frequency, which is performed
in a different manner than the bar code system in which a reader identi?¬?es a bar code
through the light.
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