Lesson Title: RFID Frequency Bands

Dale R. ThompsonComputer Science and Computer Engineering Dept.

University of Arkansas

http://rfidsecurity.uark.edu 1

This material is based upon work supported by the National Science Foundation under Grant No. DUE-0736741.

Any opinions, findings and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation (NSF).

Copyright © 2008, 2009 by Dale R. Thompson {d.r.thompson@ieee.org}

Frequency and Wavelength • f = frequency (cycles/s = Hz)• λ = wavelength (m)• c = speed of light in vacuum = 3E8 m/s• c= λ*f

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Radio Frequency (RF) Bands

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Unlicensed Industrial, Scientific, and Medical (ISM) bands

• Goals– Unlicensed spectrum– Share spectrum– Minimize interference

• Techniques– Limits on power– Allowed modulation techniques– Antenna gain– Conditions of operation

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FCC Rules for ISM Band Wireless Equipment

• Federal Communications Commission (FCC) regulates frequencies in United States

• FCC regulations appear in title 47 of the United States Code of Federal Regulations (47CFR) and radio spectrum issues are the subject of part 15 of the FCC rules

• Industrial, Scientific and Medical (ISM) devices

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RFID Frequency Bands, part 1

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FrequencyBand

Designation Application Comments Source

125/135 kHz LFLivestock, pets, humans

125 kHz in US, 135 kHz in rest of the world (Dobkin, 2008)

3.155 - 3.400 MHz HF

Electronic article surveillance (EAS) (Finkenzeller, 2003)

6.765 - 6.795 HF (Finkenzeller, 2003)7.400 - 8.800 MHz HF EAS (Finkenzeller, 2003)

13.553 - 13.567 MHz HF

Contactless smart cards (ISO 14443, 15693), item management (ISO 18000-3) (Finkenzeller, 2003)

26.957 - 27.283 HFSpecial applications (Finkenzeller, 2003)

RFID Frequency Bands, part 2

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FrequencyBand

Designation Application Comments Source

433 MHz UHF

Item management (ISO 18000-7)

Battery powered tags for identifying and locating containers (Dobkin, 2008, p. 19)

865 - 865.6 MHz UHFItem management

Europe only, listen before talk, 100 mW ERP

(rfid-handbook.de website)

865.6 - 867.6 MHz UHF

Item management

Europe only, listen before talk, 2 W ERP

(rfid-handbook.de website)

867.6 - 868 MHz UHFItem management

Europe only, listen before talk, 0.5 W ERP

(rfid-handbook.de website)

902 - 928 MHz UHF

Item management (ISO 18000-6)

US/Canada, 4W EIRP spread spectrum, FCC Part 15 (Finkenzeller, 2003)

2.400 - 2.483 GHzUHF

(microwave)Traffic management

US/Canada, 4W EIRP spread spectrum, FCC Part 15

(Dobkin, 2008, p. 17), (Finkenzeller, 2003) and website

5.725 - 5.875 GHz SHFrarely used for RFID

4 W EIRP US/Canada, 0.5 W Europe

(rfid-handbook.de website)

Inductive Coupling (Near Field)

• Wavelength much larger than antenna– Inductively coupled for communication– Propagation time from reader to tag is fraction of cycle time– Act like a transformer

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Radiative Coupling• Antenna size comparable to the wavelength

– Radiative coupling for communication– Propagation time from reader to tag is longer than a single RF cycle– Antenna launches a electromagnetic wave– Use backscattering from tag to reader

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Common passive RFID frequency bands

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FCC Rules for 902-928 MHz• Maximum transmitter power limited to 1 watt for

systems that frequency hop across at least 50 channels (Gen-2 readers typically run 1 watt and frequency hop across 50 channels)

• Maximum EIRP (effective isotropic radiated power) is limited to 4 watts (36 dBm). For antenna gain greater than 6 dBi must reduce power. (For 1 watt reader transmitter the maximum gain antenna can be up to 6 dBI.)

• When frequency hopping, the transmitter must not use one frequency greater than 0.40 seconds within a 20 second period

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Contact InformationDale R. Thompson, Ph.D., P.E.Associate ProfessorComputer Science and Computer Engineering Dept.JBHT – CSCE 5041 University of ArkansasFayetteville, Arkansas 72701-1201

Phone: +1 (479) 575-5090FAX: +1 (479) 575-5339E-mail: d.r.thompson@ieee.orgWWW: http://comp.uark.edu/~drt/

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Copyright Notice, Acknowledgment, and Liability Release

• Copyright Notice– This material is Copyright © 2008, 2009 by Dale R. Thompson. It may be freely redistributed in its

entirety provided that this copyright notice is not removed. It may not be sold for profit or incorporated in commercial documents without the written permission of the copyright holder.

• Acknowledgment– These materials were developed through a grant from the National Science Foundation at the

University of Arkansas. Any opinions, findings, and recommendations or conclusions expressed in these materials are those of the author(s) and do not necessarily reflect those of the National Science Foundation or the University of Arkansas.

• Liability Release– The curriculum activities and lessons have been designed to be safe and engaging learning

experiences and have been field-tested with university students. However, due to the numerous variables that exist, the author(s) does not assume any liability for the use of this product. These curriculum activities and lessons are provided as is without any express or implied warranty. The user is responsible and liable for following all stated and generally accepted safety guidelines and practices.

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