Transcript
UHF-Technology
Vorlesung RFID Systems Benno Flecker, Michael Gebhart TU Graz, Sommersemester 2014
RFID System A traditional passive label (tag) is queried and it responds with it’s ID accordingly. Power and commands are transferred with different frequencies (UHF [860 – 960MHz], HF [13.56MHz], LF [125 & 134.2kHz].
Power & Commands
0101011011010111010 1010101100110101011
RFID Systems
Serial Number / Data
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Interactive RFID | I2C devices I2C serial interface to traditional RFID Enables bidirectional communications between electronics and the traditional RF interface RFID tag would typically be incorporated in the electronic PCB
RFID
I2C
Electronic Device
Bidirectional Communications
RFID Systems
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RFID Technology Elements •Slotted Aloha •Binary Tree
•One Time Programmable (OTP) •Read Only (RO) •Read / Write (R/W)
Anti-collision Handling
Memory
•Sensors •Localization •Cryptography
Special Features
Power Supply
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Operating Frequency
•125 /134.2 kHz •13.56 MHz •860 - 960 MHz •2.45 GHz •(5.6 GHz)
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•Passive •Semi-passive •Active
ID Format
•UID •EPC 96bit
Protocol Transponder Type
•Tag (rigid) •Label (flexible)
•Reader Talks First (RTF) •Tag Talks First (TTF)
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Used RFID technology and its properties Low frequency (125kHz) – – – –
Read Range ~ 1m – one tag each time Works well in harsh environment Transponder cost System cost
High frequency (13.56MHz) – – – –
Read Range ~ 1.5m – 40 tags at the same time Works well in harsh environment Transponder cost System cost
Ultra high frequency (840-960MHz) – – – –
Very long read ranges of up to 10+m – 1000 tags/sec Susceptible to harsh environment Transponder cost System cost
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LF Technology Physical concept:
Inductive coupling
Operating frequency: 125/134.2 kHz
Antenna: Coil
Operating distance: Up to 1m
Environmental influences: Standards: ISO 11784/85 Animal ID, TTF ISO 14223 RTF & TTF ISO 18000-2 Item Management
National Regulations: Worldwide harmonized
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Weak influence on operating distance Works in metal environment
Application:
Animal identification Industrial environment Access Control
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HF Technology Physical concept:
Inductive coupling
Operating frequency: 13.56 MHz
Antenna: Coil
Operating distance:
Vicinity: up to 1.5m Proximity: up to 10cm
Standards:
ISO 15693 Vicinity Card ISO 14443 Proximity Card ISO 18000-3 Item Management HF EPC Gen2
National Regulations: Worldwide harmonized
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Environmental influences:
Weak influence on operating distance Works in metal environment
Application:
Libraries Public transport Product identification Access control, …
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UHF Technology Physical concept: EM – wave propagation
Operating frequency: 860 – 960 MHz
Antenna: Dipole and/or loop
Operating distance: Far field: up to 7m Near field: up to 10cm
Environmental influences: Standards EPC Class I Gen2 ISO 18000-6 Item Management
National Regulations: No worldwide harmonized
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Influence on operating distance by reflection and absorption
Application:
Pallets and container ID Fashion Retail Electronics
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Information from EPCglobal HP (Free Download) Class 1 Generation 2 UHF Air Interface Protocol Standard "Gen 2" http://www.gs1.org/gsmp/kc/epcglobal/uhfc1g2 EPC Tag Data Standard (TDS) http://www.gs1.org/gsmp/kc/epcglobal/tds/ EPC Tag Data Translation (TDT) Standard http://www.gs1.org/gsmp/kc/epcglobal/tdt/ Mask Designer ID Assignment (MDID) http://www.gs1.org/epcglobal/standards/mdid Frequency Regulations UHF http://www.gs1.org/docs/epcglobal/UHF_Regulations.pdf
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Frequency allocation by countries
Frequency Regulations UHF http://www.gs1.org/docs/epcglobal/UHF_Regulations.pdf
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PEIRP - Equivalent Isotropic Radiated Power vs. PERP - Effective Radiated Power PERP... transmitted power compared to a dipole antenna ERP: Effective radiated power. The amount of power that would be necessary at the input terminals of a reference half-wave dipole antenna in order to produce the same maximum field intensity. PEIRP... transmitted power compared to an isotropic antenna EIRP:Equivalent isotropically radiated power (EIRP). The amount of power that a theoretical isotropic antenna would need to emit to produce the peak power density observed in the direction of maximum antenna gain.
PERP
PEIRP = 1.64
1.64 is equivalent to 2.15dB Gain and Directivity
Ptransmitted G= ⋅D Pconducted
– if the antenna has no electrical losses, then G = D
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Maximum Radiated by countries (PEIRP)
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Energy Transmission from Reader to TAG Transferred power from a reader antenna to the chip
PChip
λ2 = PEIRP ⋅ ⋅ ϑMatching ⋅ϑPolarisation ⋅ ϑ Antenna ⋅ GLabel 2 (4 ⋅ π ⋅ R)
– ϑMatching ... Antenna matching factor(1− | Γ |2 ) – ϑPolarisation ... Polarisation losses – ϑAntenna ... efficiency of the label antenna (Pradiated / Pin)
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Read Range of an UHF/GHz Chip
Rmax
PEIRP ⋅ GLabel ⋅ λ2 ⋅ ϑMatching ⋅ϑPolarisation ⋅ ϑ Antenna = 2 (4 ⋅ π ) ⋅ PChip
Example I (UHF) under US regulations: PEIRP = 4 W; GLabel = 1.64; f = 915MHz; PCHIP = 35µW
ϑMatching = 0.8; ϑPolarisation = 1; ϑAntenna = 0.5
Rmax
4W ⋅1.64 ⋅ 0.33m 2 = ⋅ 0.8 ⋅ 1 ⋅ 0.5 = 7.19m 2 −6 (4 ⋅ π ) ⋅ 35 ⋅10 W
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Read Range of an UHF/GHz Chip
Example II (UHF) under EN 302 208 European regulation: PERP = 2 W equals PEIRP = 3.28W; GLabel =1.64 f = 869MHz; PCHIP = 35µW
ϑMatching = 0.8 ; ϑPolarisation = 1 ; ϑAntenna = 0.5
Rmax
3.28W ⋅1.64 ⋅ 0.35m 2 = ⋅ 0.8 ⋅ 1 ⋅ 0.5 = 6.90m −6 2 (4 ⋅ π ) ⋅ 35 ⋅10 W
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UHF Memory structure
Reserved Memory EPC Memory TID User Memory RFID Systems
• Access and Kill Password
• EPC Electronic Product Code • Code can be written by user • TID Tag Identifier (preprogrammed & locked) • IC Manufacturer information, Unique serial number • Manufacturing, quality and product related data storage • User related data storage
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Anti collision algorithm
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Communication with the tag
Inventory (1 Communication step)
Command (e.g. READ TID)
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Tag Inventory flag
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Tag persistence
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Effect on search mode and sessions Tag in the field Dual Target Reader A&B
Tag out of the field
A B A B A B A B A B A B A B A B A R R R R R R R R R R R R R R R R R
Singel Target Session 1
A R
PT S1 B
A R
PT S1 B
A R
PT S1 B
A R
PT S1 B
A R
Reader only A
PT S2 or S3 Singel Target Session 2 or 3
A R
B
Reader only A R: READ PT S1: Persistance Time Session 1 PT S2 or S3: Persistance Time Session 2/ 3
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Environmental Influence - Overview UHF-Characteristics – Absorption/Damping – Reflection – Refraction – Diffraction – Penetration into Liquids – Interference – Polarisation
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Environmental Influence - Overview Absorption/damping – Only vacuum is passed by electromagnetic energy without absorption – Absorbed energy is typically converted to heat – Absorbing materials between the reader antenna and the label antenna strongly determines the operating range of the label
Absorbing materials – Water, water absorbing materials – Rubber, adhesives, …
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Environmental Influence - Overview Reflections – A pure reflection of the travelling wave, will conserve the energy of the field – Will lead to interferences – Constructive interference may lead to super ranges – Destructive interferences may lead to „holes“ in the operational area – Reduce this no-read situations with multiple antennas
Reflecting materials – Metal, water, concrete – Metallic paints - films - foils
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Environmental Influence - Overview
Refraction – caused by the velocity difference of the EM wave between one propagation medium and a second – lead to a change of the wave direction
medium border
εr RFID Systems
εr1 Seite 25
Environmental Influence - Overview Diffraction – occurs by passing a sharp corner – Huygens’ principle is based on this process
Representation of Radio Waves as Wavelets
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Environmental Influence - Overview Penetration into Liquids – Depending on the electrical conductivity of the liquid – Water has a high electrical conductivity and will tend to absorb and reflect EM waves – Oil derivates allows an EM wave to pass with a low level of attenuation, if no additives are used.
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Environmental Influence - Reflections Application Effects
Expanding operation range – guiding travelling waves with the help of e.g. metal (Truck, ...)
Shielding – wanted • separation from places of identification • hiding items from being identified (wrapping into conducting foil)
– unwanted • e.g. labels inside a pallet of tin cans may not be recognized
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Environmental Influence - Interferences Example – Propagation of travelling waves in free space
Z
Y
ideal dipole
X
Different field-strength
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Idealized linear polarized dipole Polarisation: y - axis Picture: xz - plane
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Environmental Influence - Interferences Example – Propagation of travelling waves in free space
Z
Y
ideal dipole
X
Idealized linear polarized dipole Polarisation: y - axis Picture: xy - plane
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Environmental Influence - Interferences Example – Propagation of travelling waves with reflecting floor
field-holes
Idealized linear polarized dipole Polarisation: z - axis Picture left: zy - plane / Picture right: xy - plane
Z
Y X
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Environmental Influence - Interferences Example – Propagation of travelling waves with reflecting floor
Z
Y X
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Idealized linear polarized dipole Polarisation: y - axis Picture left: xz - plane / Picture right: xy plane
super-range
field-hole
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Environmental Influence - Interferences Example – Propagation of travelling waves with reflecting wall
Z
Y X
...wall Idealized linear polarized dipole Polarisation: y - axis Picture: xz - plane
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Environmental Influence - Interferences Application Effects Close to reflecting planes, interferences will lead to standing waves
•Moving labels may cross spots of „field nulls“ and may loose it´s internal states Z Y X
Idealized linear polarized dipole Polarisation: y - axis Picture: xz - plane
RFID Systems
...wall
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Multi Antenna Arrangements
A single reader antenna will in many cases not be sufficient for desired applications
Preferred way to use more than one reader antenna is multiplexing, controlled by the reader
The reader starts its task (e.g. identify all tags in the field) at the first antenna. After finishing this job the next antenna can be used ....
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Multi Antenna Arrangements Positioning
A given operational space has to be covered by the sum of the operational spaces of all individual antennas – The more overlap the antenna arrangement has, the more reliable the identification will be – For applications with many, fast moving items the antenna switching may be improved by external detectors e.g light barrier – Operational spaces may be a affected by the items that have to be identified (shielding, absorbing)
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Multi Antenna Arrangements Positioning
Parallel mounted Gate antennas
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Content
Antenna Design
Antenna design Inputs
Antenna design Parameter
Direct chip assembly
Pmin measurement
Identify the right tag
Label / Tag provider
RFID PCB antenna designer
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Antenna design inputs IC Dimensions, coating Size Label Size, Antenna Size Antenna Substrate Material; Thickness Antenna Conductive materials Material; Thickness; Line width; Gap width; min. corner radius Performance Required Frequency Bands; US; EU Application Free Air; Cardboard; Plastic; Other material Stacked tags Max. no. of tags; Min. distance of tags Chip Attachment - Direct Attach: Expected Assembly Capacitance
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Assembling –Parasitic Capacitances
Cparasit
Cchip
R
C tot = C parasit + C chip
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Reference antenna design FF9510
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FF9510 – Change loop size 7
6
Range [m]
5
4
3
Delta Loop = 0 mm Delta Loop = 0.57 mm Delta Loop = 1.05 mm Delta Loop = 1.52 mm Delta Loop = 2.00 mm
2 Loop Size Increase
1
0 0.7
0.75
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0.8
0.85
0.9
0.95 FREQ [GHz]
1
1.05
1.1
1.15
1.2
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FF9510 – Change dipole length 7 dL dipole = dL dipole = dL dipole = dL dipole = dL dipole =
6
0 mm - 0.75 mm - 1.75 mm - 2.25 mm - 3.00 mm
Rang [m]
5
4
3
2
L decrease
1
0 0.7
0.75
0.8
0.85
0.9
0.95
1
1.05
1.1
1.15
1.2
Freq [GHz]
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FF9510 – Change connection dipole loop 7
6
Range [m]
5
4
3
2 Distance Reduction
Distance Reduction
1
0 0.7
0.75
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0.8
0.85
0.9
0.95 FREQ [GHz]
1
1.05
Delta Dipole = 0 mm Delta Dipole = - 1.2 mm Delta Dipole = - 2.4 mm Delta Dipole = - 3.6 mm Delta Dipole = - 4.8 mm Delta Dipole = - 6.0 mm
1.1
1.15
1.2
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FF9510 – Total Gain 868 MHz
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Direct Chip attach 150µm, 120µm with 18µm gold bumps Pressure Temperature ACP/ACF Anisotropic Conductive Paste/Foil (Adhesive with conducting particles 10k - 40k particles per mm2)
Antenna Structure Pressure Temperature
Material: Al, Cu, Ink Etched, Printed, Laser cutted
Substrate Material: Paper, PET, PC; Thickness 38µm or 50µm
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Antenna gap
A… Maximum antenna gap (average distance + tolerance) IC placement accuracy MB +/-50µm
Remark: Add etching tolerances - Check with the antenna supplier!
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Assembled die
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Pmin – Measurement setup
EPC global document “Tag Performance Parameters and Test Methods Version 1.1.1”.
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Pmin - Anechoic chamber
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FF9510 120 µm Reference materials
Measured with Voyantic Tagformance (http://www.voyantic.com/)
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Identify the right tag Size Application Memory Read / Write Sensitivity Write cycles Data retention
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Label / Tag provider Avery Dennison (http://rfid.averydennison.com/) Smartrac (http://www.smartrac-group.com/en/) Confidex (http://www.confidex.net/) …
RFID Systems
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RFID PCB Antenna Designer Target: Easy access to customized PCB antennas
Supported ICs: • UCODE G2iL (SL3S1203) • UCODE G2iM (SL3S1013) • UCODE I2C (SL3S4011) • Link: http://www.nxp.com/documents/design_tools/re direct_transim_rfid.html
RFID Systems
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RFID PCB Antenna Designer - Design flow IC Selection Specification
Synthesis
EM Validation
Simulation
Step 1
Step 2
Step 3
Step 4
Step 5
Choice of three different RFID UHF ICs
UHF frequency selection Available space for antenna
Antenna type Antenna topology
PCB board dimensions PCB board material
Start CST Simulation After simulation report and download
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Design flow – Step 1 - IC selection
Supported ICs: • UCODE G2iL (SL3S1203) • UCODE G2iM (SL3S1013) • UCODE I2C (SL3S4011) • Access Product Info • Access datasheet
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Design flow – Step 2 - Specification
UHF Selection: • Region • Power level Available antenna space PCB top layer type
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Design flow – Step 3 - Synthesis
Topology selection Topology - Geometry
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Design flow – Step 4 – EM Validation
Board Dimensions PCB Specification
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Design flow – Step 5 - Simulation
Login required for starting the simulation! Simulation time counter
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Design flow – Step 6 - Results
Download: • CST file • DXF file • Summary PDF • Summary XLS
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Thank you for your Audience! Please feel free to ask questions...
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