Basics of RFID technology Thomas Holtstiege Technical Manager EECC October 2009
About the European EPC Competence Center (EECC) First European EPCglobal accredited performance test center Active since 2005 Leading manufacturer-independent European RFID Lab www.eecc.info 4 Shareholders GS1-Germany 35%, DHL 30%, Metro Group 30%, Arcandor 5% The goal: - Acquisition of new RFID Users - Successful RFID Projects - Financial Independency
Services & unique features RFID Academy EECC Technical Services RFID - Consultancy EECC Research Best quality by first-class speakers technical partners scientific institutes (Auto ID Lab St. Gallen/ETH Zürich) Tests and hardware certifications at the EECC Lab Experience from more than 1000 tests Transpondertests (ATP), Readers & Antennae Consultancy at all steps of RFID Adoption RFID Roadshow Quality and transparency right from the start Worldwide approved R&D Manufacturer-independent UHF Tag Performance Survey New in 2009: Including on-metal-tags 2 superregional Show Rooms DHL Innovation Center, Metro RFID Innovation Center
Basics of RFID and EPC Contactless transmission of product data by Radio Frequency Identification (RFID) Main item of the technology: the RFID-Transponder Chip Antenna EPC Electronic Product Code (EPC): Objects get a unique identity E.g. SGTIN: Header EPC-Manager-Number Product-Number Serial Number
Examples of RFID Labels
Components of an RFID System IT infrastructure Antenna Transponder (Tag) Reader (Interrogator)
Reading process
Technology Type of construction Hard tags Flexible (Label) Power supply Passive Battery assisted Active Protocols Many proprietary Class 1 Gen 2 RFID technology overview Frequency bands ~ 130 khz (LF) 13.56 MHz (HF) ~ 900 MHz (UHF) 2.45GHz (Microwave) Special functions Sensors Cryptography EAS Data processing Read Only (RO) One Time Programmable (OTP) Read / Write (R/W) Data formats EPC 64bit EPC 96bit User memory Many others
Used frequencies Complete electromagnetic spectrum Electric Waves Radio Waves Infra-red Visible Light Ultra- Violet X-Rays Gamma Rays Cosmic Rays Radio Spectrum spectrum 9kHz 30kHz 300kHz 3000kHz 30MHz 300MHz 3000MHz 30GHz 300GHz 3000GHz VLF LF MF HF VHF UHF SHF EHF Not designated VLF Very Low Frequency VHF Very High Frequency LF Low Frequency UHF Ultra High Frequency MF Medium Frequency SHF Super High Frequency HF High Frequency EHF Extremely High Frequency
Transmission principles Principle Way of transmission Frequency Inductive coupling M Magnetic field Near field LF (125 khz to 135 khz) HF (13.56 MHz) Electromagnetic (EM) wave propagation EM wave propagation with back scattering Far field UHF 433, 860-960 MHz, Microwave (2.45 GHz)
Inductive coupling (magnetic, transformer principle) Frequencies 125/134 khz, 13.56 MHz Antennae Coils Read range up to 1,5 m (Gate with ISO cards / big tags) Applications Proximity (up to 10 cm) Vicinity (up to 2 m)
EM wave propagation Frequencies 860-960 MHz, 2.45 GHz Antennae Dipoles, cross dipoles Read range up to 10 m Applications Long range (supply chain)
Reading of a tag from different directions Reading options of a vertically arranged transponder: Top: No Back: Yes Most UHF transponders look and work like dipoles Left: Yes Right: Yes These tags can be read only from a direction perpendicular to its main axis Materials (products) can change the directivity Front: Yes Bottom: No
Read range The read range of an RFID system depends on different parameters. The most important ones are: Transmit power Transponder type Subsurface material
Influence of the environment Absorption / power loss Reflections External interference
Absorption / power loss All materials absorb energy from an electromagnetic field (the field weakens), some materials more, some less A weak field implies a small read range Absorptive materials close to a tag are the main reason for a reduced read range Absorptive materials: Water, aqueous materials Rubber, adhesives etc.
Reflections Electromagnetic waves are reflected by different materials Reflections cause superposition with field ripple There are areas with - a strong field (maximum, leads to overshoot)) - a weak field (minimum or hole ) The distance between minimum und maximum is halve a wave length, typically 17 cm at 867 MHz The holes can be reduced by multiple antennas or by moving the tag or the antenna Worst case is a tag directly mounted on metallic subsurface no chance to read Reflective materials: Metal, water, reinforced concrete Metallic paint, metallic foils
External interference Radio waves are used in numerous applications Similar to the acoustic situation in a crowded room, the more voices speaking at the same time, the more difficult they are to understand RFID readers need to share the UHF bandwidth with other wireless devices such as fire alarms, remote controls, garage door openers, ham radio operators... Rain, icing and condensation can further reduce transponder read range