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BLOCKING READER: DESIGN AND IMPLEMENTATION OF A ...

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2.1 Introduction<br />

CHAPTER 2<br />

ELECTROMAGNETIC’S <strong>OF</strong> RFID<br />

It is important to know the Electromagnetic’s of Radio Frequency Identifi-<br />

cation(RFID), the physics concerning the communication between reader and tag.<br />

Knowledge of the fields and different laws governing the entire RFID System commu-<br />

nication will help us to give more insight to analysis. The thesis consist of analysis<br />

of RF Radiation patterns of the Blocking reader. The RF front end of the blocking<br />

reader design consists of proper selection of the type of modulation, frequency and<br />

power. This chapter gives a small introduction to all the theories involved in the<br />

communication like Electric field, Magnetic field theory, equations governing them,<br />

modulation, antenna theory, multi-path and polarization.<br />

2.2 Basic RFID System<br />

A typical RFID system is as shown in the Figure 2.1. It consists of a Reader<br />

which readers the Tag information and transmits to the back-end information system<br />

for further processing. Unlike barcodes the Tags communicate wirelessly transmitting<br />

the identifier to the Reader. There are different types of RFID systems.<br />

RFID systems can be classified based on frequency and based on communica-<br />

tions. In this thesis we will only talk about passive UHF RFID system. UHF systems<br />

are far field operated systems where data is communicated through electromagnetic<br />

waves. UHF band allowable in US for RFID communication is 902-928 MHz. Passive<br />

RFID systems consists of Passive UHF Tags. Passive Tags are battery-less that de-<br />

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