Lesson Title: RFID Frequency Bands Dale R. Thompson Computer Science and Computer Engineering Dept. University of Arkansas 1 This material is based upon work supported by the National Science Foundation under Grant No. DUE 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

Frequency and Wavelength f = frequency (cycles/s = Hz) λ = wavelength (m) c = speed of light in vacuum = 3E8 m/s c= λ*f 2

Radio Frequency (RF) Bands 3

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 4

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

RFID Frequency Bands, part Frequency Band DesignationApplicationCommentsSource 125/135 kHzLF Livestock, pets, humans 125 kHz in US, 135 kHz in rest of the world(Dobkin, 2008) MHzHF Electronic article surveillance (EAS) (Finkenzeller, 2003) HF (Finkenzeller, 2003) MHzHFEAS (Finkenzeller, 2003) MHzHF Contactless smart cards (ISO 14443, 15693), item management (ISO ) (Finkenzeller, 2003) HF Special applications (Finkenzeller, 2003)

RFID Frequency Bands, part Frequency Band DesignationApplicationCommentsSource 433 MHzUHF Item management (ISO ) Battery powered tags for identifying and locating containers(Dobkin, 2008, p. 19) MHzUHF Item management Europe only, listen before talk, 100 mW ERP (rfid-handbook.de website) MHzUHF Item management Europe only, listen before talk, 2 W ERP (rfid-handbook.de website) MHzUHF Item management Europe only, listen before talk, 0.5 W ERP (rfid-handbook.de website) MHzUHF Item management (ISO ) US/Canada, 4W EIRP spread spectrum, FCC Part 15(Finkenzeller, 2003) GHz UHF (microwave) Traffic management US/Canada, 4W EIRP spread spectrum, FCC Part 15 (Dobkin, 2008, p. 17), (Finkenzeller, 2003) and website GHzSHF rarely 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 8

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 9

Common passive RFID frequency bands 10

FCC Rules for 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

Contact Information Dale R. Thompson, Ph.D., P.E. Associate Professor Computer Science and Computer Engineering Dept. JBHT – CSCE University of Arkansas Fayetteville, Arkansas Phone: +1 (479) FAX: +1 (479) WWW:

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. 13