资料介绍
Radio Frequency Identification (RFID) systems use
radio frequency to identify, locate and track people,
assets, and animals. Passive RFID systems are
composed of three components – an interrogator
(reader), a passive tag, and a host computer. The tag
is composed of an antenna coil and a silicon chip that
includes basic modulation circuitry and non-volatile
memory. The tag is energized by a time-varying
electromagnetic radio frequency (RF) wave that is
transmitted by the reader. This RF signal is called a
carrier signal . When the RF field passes through an
antenna coil, there is an AC voltage generated across
the coil. This voltage is rectified to supply power to the
tag. The information stored in the tag is transmitted
back to the reader. This is often called backscattering.
By detecting the backscattering signal, the information
stored in the tag can be fully identified. AN680
Passive RFID Basics
Author: Pete Sorrells
Modulation
Microchip Technology Inc. Periodic fluctuations in the amplitude of the carrier
used to transmit data back from the tag to the reader.
Systems incorporating passive RFID tags operate in
INTRODUCTION ways that may seem unusual to anyone who already
Radio Frequency Identification (RFID) systems use understands RF or microwave sy
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