RFID DESIGN STUDIES Dr. KVS Rao Intermec Technologies Everett, WA, USA Prof. Raj Mittra Pennsylvania...
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Transcript of RFID DESIGN STUDIES Dr. KVS Rao Intermec Technologies Everett, WA, USA Prof. Raj Mittra Pennsylvania...
RFID DESIGN STUDIES
Dr. KVS RaoIntermec TechnologiesEverett, WA, USA
Prof. Raj MittraPennsylvania State UniversityUniversity Park, PA, USA.
Applications
• Electronic Toll Collection
• Access Control• Animal Tracking• Inventory Control• Tracking Runners in
Races!
Introduction
Radio Frequency Identification (RFID) System
- Background Information•Applications of RFID
• High Frequency (13.56MHz)• Supply Chain
• Wireless Payment
• Libraries Book ID
• Ultra High Frequency (902 – 928 MHz)• Supply Chain
• Sensors
• Libraries
• Microwave Frequency (2.45GHz)• Supply Chain
• Sensors
• Electronic Toll Payments
Design Challenges
• Small Size• Planar• UHF Frequency
Allocation – Europe 866-869 MHz– North America 902-
928 MHz
• Impedance Matching– ASIC Chip: High
Capacitive Value, Small Resistive Value
• Environmental Conditions
Antenna Parameters
• Characteristic Impedance– Power
• 3-Dimensional Radiation Patterns
• Maximum Directivity
224
( )a s
s a s a
R RP
R R X X
where Zwhere Zaa = R = Raa + j X + j Xa a is the antenna impedance,is the antenna impedance,
and Zand Zss = R = Rss + j X + j Xs s is the source impedance.is the source impedance.
radP
UD max
max
4
where Uwhere Umaxmax is the radiation intensity is the radiation intensity
in maximum direction, in maximum direction, and Pand Pradrad is the total radiated power. is the total radiated power.
Hybrid loop antenna
• Length of the antenna ~ one operating wavelength in free space
• Outer loop terminated by inner loop size reduction• Simple structure (one layer of dielectric substrate)• Antenna impedance must be highly inductive
Top View of the antenna
Hybrid loop antenna (cont‘d)
• Realize a high value for the inductance by: Changing the loop area (L ~ A) Changing the length of the perimeter
Top View of the modified antenna
Hybrid loop antenna : First design
• Perimeter of the loop antenna : 244 mm • Size used by the antenna : 39 x 40 (mm)• Resonance frequency : ~0.5 GHz and 1.26 GHz• Reactance +300 Ω at 1.01 GHz
Input Impedance
Hybrid loop antenna : First design (cont‘d)
• Not omnidirectional Pattern in the xy-plane
Non strictly symmetry of the geometry
Far Field Pattern (normalized)
xy-planexy-planexz- (blue) and yz-(red) planexz- (blue) and yz-(red) plane
Hybrid loop antenna : Parametric study
• Li = 16 (red graph) mm Li = 10 mm (blue graph)• Perimeter , Loop area : L • Perimeter 244 mm 232 mm
Changing the length of the inner loop Li
Hybrid loop antenna : Parametric study
• Wi = 28 (red graph) mm Wi = 30 mm (blue graph)• Perimeter , Loop area : L • Perimeter 248 mm 252 mm
Changing the width of the inner loop Wi
Hybrid loop antenna (cont‘d)
• Current distribution : small current in the top part of the antenna small influence on the inductance Meandering
Far Field Pattern and Current distribution at 910 MHz
Meandered Hybrid loop antenna
• Perimeter 252 mm 302 mm• Maximum percentage at 910 MHz
Top View of the meanderd antenna
Hybrid Loop Antenna
• Length of the antenna has a greater effect on the input impedance more than does the loop area
• Meandering technique reduces the size of the antenna• Small percentage power delivered to the antenna attributable to very small
resistive part of the input impedance• The developed design did not prove to be too useful
OBSERVATIONS
Dual cross-dipole
• Meandering dipole size reduction• Cross-polarization sensitivity dual dipole• Ground plane can act as reflector gain
Top and Side Views of the Antenna Structure
Dual cross-dipole : Design#1
• Length of the antenna : 218 mm ~0.66 λ (at 910 MHz)• Area used by the antenna : 51 x 51 (mm)• Reactance is too small in the desired frequency Length of the antenna • Resistive part is again very small
Input Impedance
Dual cross-dipole : Design#2
• “Load bar“ is added
• Length of the antenna : 258 mm ~ 0.78 λ (at 910 MHz)
• f300 at 900 MHz
Top View
Dual cross-dipole : Design#2
• ~80 % of the power is delivered to the antenna• Narrow bandwidth (10.5 MHz more than 50 % is delivered)• Min. AR 3 dB (860 MHz – 960 MHz)
Far Field Pattern/Power delivered to the antenna/ Axial Ratio
Dual cross-dipole : Parametric study
• Decreasing h, increases the resonance frequency• By varying the height, input impedance can be adjusted for a good matching
Influence of the height of the antenna
Dual cross-dipole : Parametric study
• Increasing the dielectric constant , drops the resonance frequency length of the antenna
• Area used by the antenna was decreased ~ 19 % by using a higher dielectric (4 instead of 2.2 )
• Max. Power delivered to the antenna was sligthly higher for the case with the higher dielectric constant (79 % vs 86 % )
• Bandwidth wasn‘t influenced
Influence of the dielectric constantInput Impedance and new design
Dual cross-dipole : New design
• Area used by the antenna reduced ~ 35 % compared to the inital design (second case) and ~21 % compared to the previous case
• Max percentage for the power plot : ~81 % (79 % second case / 86 % previous case)
• Bandwidth didn‘t change
New design/Power delivered to the antenna
Inductively coupled Feed
• Strength of the coupling depends on h2 and the size of the loop• Inductive coupling modeled by a transformer• Analyzing the input impedance by varying the size and shape of the and shape of the
looploop
Top View and structure
bodyloopin Z
MZZ
22
Inductively coupled Feed (cont‘d)
• Increasing the loop size, increase the inductance• With this method the reactance increases ~200 Ω• Two operating range frequency• Antenna size needs to be adjusted (increased)
Changing length of the loop
Inductively coupled Feed (cont‘d)
• Same experiment as before (changing the size of the loop)• For one design we realized a very high percentage of power
delivered (98 % at 899 MHz)• Bandwidth was narrow
Changing the shape of the feeding loop
Inductively coupled Feed (cont‘d)
• Narrow bandwidth• Operating frequency can be varied by changing the size of
the feeding loop • Antenna size must be increased to operate in the desired
frequency range if we use a square loop.
OBSERVATIONS
Antenna Measurement
Top View of the antenna
Input Impedance Comparison : Measurement et Simulation
Field Pattern normalized (910 MHz) - Comparison
Measurement Simulation
-Anechoic chamber not ideal for 910 MHz-Different feeding part (balun for measurement)-Infinite substrate size used for simulation
PLATFORM-TOLERANT RFID DESIGNS
Parameter Size (mm)
L 62
W 51.3
H 3
S 5
gap (867/915 MHz) 1
gap (867/940 MHz) 1.9
r 2.35
ASIC Chip:
Zc=10-j160 [] at 867 MHz
Zc=10-j150 [] at 915 MHz
Zc=10-j145 [] at 940 MHz
Dual-Band PIFA Design
•Dual-band Frequency Operation
•Open-Ended Stub
•Gap Dimension and Stub Dimension Used to Tune
•Platform Tolerance
•Dominating Horizontal Current Distribution
•Widening Short, Vertical Inductance Reduced, Antenna Lowered
Dual-Band PIFA Design
•Mounting Materials
•Dimensions
•900 mm x 900 mm
•(4 x 4 )
•Thickness=13 mm
•Cardboard (r=2.5)
•Glass(r=3.8)
•Plastic(r=4.7)
Dual-Band PIFA Design
Impedance [867/915 MHz] Dual-Band PIFA DesignImpedance [867/915 MHz] Dual-Band PIFA Design
Real Impedance
0
50
100
150
200
250
300
850 858 865 873 880 888 895 903 910 918 925 933
Frequency [MHz]
No Material Cardboard Glass Plastic
Imaginary Impedance
0
50
100
150
200
250
300
850 858 865 873 880 888 895 903 910 918 925 933
Frequency [MHz]
No Material Cardboard Glass Plastic
Power Dual-Band PIFA DesignPower Dual-Band PIFA Design
Power (867 MHz)
Power (915 MHz)
Power (940 MHz)
No Material 83.49 64.92 74.07
Cardboard 54.53 86.28 80.5
Amount Increased
-28.96 21.36 6.43
No Material 83.49 64.92 74.07
Glass 54.81 80.72 72.9
Amount Increased
-28.68 15.8 -1.17
No Material 83.49 64.92 74.07
Plastic 58.3 85.72 72
Amount Increased
-25.19 20.8 -2.07
Radiation [867 MHz] Dual-Band PIFA DesignRadiation [867 MHz] Dual-Band PIFA Design
No Material Cardboard
Glass Plastic
Conclusions Dual-Band PIFA Design
Directivity (867 MHz)
Directivity (915 MHz)
Directivity (940 MHz)
No Material 1.6841 1.832 1.8815
Cardboard 1.928 2.0704 2.3425
Amount Increased
0.2439 0.2384 0.461
No Material 1.6841 1.832 1.8815
Glass 2.4053 2.8135 3.9153
Amount Increased
0.7212 0.9815 2.0338
No Material 1.6841 1.832 1.8815
Plastic 2.9936 3.4036 4.1411
Amount Increased
1.3095 1.5716 2.2596
Environmental ChangeDual-Band PIFA Design
•Cardboard Box
• 900 mm x 900 mm
•4 x 4
•Thickness=13 mm
•Metal sheet
•450 mm x 450 mm
•2 x 2
•Height from Cardboard was Varied from 0 mm-20 mm
Radiation [867 MHz]
No Metal Metal 20 mm Under Cardboard
Power (867 MHz)
Power (915 MHz)
Peak Directivity (867 MHz)
Peak Directivity (915 MHz)
No Metal 54.53 86.28 1.928 2.0704
Metal 0 mm 76.6 80.7 3.3105 3.0219
Amount Increased
22.07 -5.58 1.3825 0.9515
Power (867 MHz)
Power (915 MHz)
Peak Directivity (867 MHz)
Peak Directivity (915 MHz)
No Metal 54.53 86.28 1.928 2.0704
Metal 10 mm 91.08 73.11 3.1872 3.0167
Amount Increased
36.55 -13.17 1.2592 0.9463
Power (867 MHz)
Power (915 MHz)
Peak Directivity (867 MHz)
Peak Directivity (915 MHz)
No Metal 54.53 86.28 1.928 2.0704
Metal 20 mm 73.25 76.82 3.2213 3.0599
Amount Increased
18.72 -9.46 1.2933 0.9895
Environmental Change Dual-Band PIFA Design
Ground Plane Optimization Dual-Band PIFA Design
No Material Directivity (867 MHz)
Directivity (915 MHz)
Original GP 1.6841 1.832
1 Inch Larger 2.3265 2.3131
2 Inch Larger 2.9306 2.918
3 Inch Larger 3.6696 3.7427
10 Inch Larger 4.5087 4.4954
Cardboard Directivity (867 MHz)
Directivity (915 MHz)
Original GP 1.928 2.0704
1 Inch Larger 2.6915 2.7059
2 Inch Larger 3.2191 3.2618
3 Inch Larger 3.1907 3.3583
10 Inch Larger 4.6297 4.687
Glass Peak Directivity (867 MHz)
Peak Directivity (915 MHz)
Original GP 2.4053 2.8135
1 Inch Larger 2.5102 2.6094
2 Inch Larger 2.9178 3.0237
3 Inch Larger 2.7375 2.7357
10 Inch Larger 3.7178 4.1891
Plastic Peak Directivity (867 MHz)
Peak Directivity (915 MHz)
Original GP 2.9936 3.4036
1 Inch Larger 2.9787 3.0035
2 Inch Larger 3.0787 2.9965
3 Inch Larger 3.1032 3.0408
10 Inch Larger 3.0544 2.9356
Ground Plane Optimization Dual-Band PIFA Design
•Impedance Matching
•Inductively Coupled Feed Loop
•Gap dimension between loop and radiators is used to tune
•Designed to match Zc=10-j150 [] at 915 MHz
•Platform Tolerance
•Reduced Current on Ground Plane
Inductively-Coupled Feed Loop PIFA Design
•Mounting Materials
•Dimensions
•200 mm x 200 mm
•( x )
•Thickness=5 mm
•Cardboard (r=2.5)
•Glass with No Loss(r=3.8)
•Glass with Loss(r=2.5) and Loss Tangent 0.002
Inductively-Coupled Feed Loop PIFA Design
Impedance
-10
10
30
50
70
90
110
130
150
170
190
0.825 0.845 0.865 0.885 0.905 0.925 0.945 0.965 0.985 1.005 1.025
Frequency [MHz]
Imaginary 9.75
Imaginary 9.5
Imaginary 9.25
Imaginary 9
Real 9.75
Real 9.5
Real 9.25
Real 9
Power 915 MHz [%]
Power 940 MHz [%]
Average
Gap 9 mm 9.09 4.39 6.74
Gap 9.25 mm 86.09 41.45 63.77
Gap 9.5 mm 77.38 34.50 55.94
Gap 9.75 mm 15.28 13.00 14.14
Optimization of Impedance in Free Space
Directivity & Radiation
Directivity (915 MHz) Directivity (940 MHz)
No Mounting Material 3.47 3.3
Cardboard (r=2.5) 3.43 2.94
Amount Increased -0.04 -0.36
Directivity (915 MHz) Directivity (940 MHz)
No Mounting Material 3.47 3.3
Glass No Loss (r=3.8) 3.4 3.25
Amount Increased -0.07 -0.05
Directivity (915 MHz) Directivity (940 MHz)
No Mounting Material 3.47 3.3
Glass With Loss (r=2.5) and loss 0.002
3.36 3.3
Amount Increased --0.11 0
867 MHz No Material
867 MHz Cardboard
Impedance
0
10
20
30
40
50
60
0.83 0.84 0.85 0.86 0.87 0.88 0.89 0.9 0.91 0.92 0.93 0.94 0.95 0.96 0.97 0.98 0.99 1
Frequency [GHz]
Gap 9.75 Gap 9.5 Gap 9.25 Gap 9 Gap 8.8 Gap 8.75 Gap 8.5
Optimization of Impedance for Cardboard
Impedance Inductively-Coupled Feed Loop PIFA
Impedance (Before Optimization)
020406080
100120140160180200
0.83 0.85 0.87 0.89 0.91 0.93 0.95 0.97 0.99 1.01 1.03
Frequency [GHz]
Imaginary No Material Imaginary Cardboard Imaginary No Loss Imaginary Glass with Loss
Real No Material Real Cardboard Real Glass with Loss Real No Loss
Impedance Inductively-Coupled Feed Loop PIFA
Impedance (Optimized)
0
20
40
60
80
100
120
140
160
180
200
0.83 0.85 0.87 0.89 0.91 0.93 0.95 0.97 0.99 1.01 1.03
Frequency [GHz]
Imaginary No Material Imaginary Cardboard Imaginary Glass No Loss Imaginary Glass With Loss
Real No Material Real Cardboard Real Glass No Loss Real Glass With Loss
Power (915 MHz) [%] Power (940 MHz) [%]
Free Space 86.09 41.45
Cardboard 16.29 6.5
Cardboard Optimized 61.19 31.69
Free Space 86.09 41.45
Glass 24.06 9.48
Glass Optimized 56.59 69.36
Free Space 86.09 41.45
Glass with Loss 11.65 23.81
Glass with Loss Optimized 61.6 52.55
Power Before and After Optimization Inductively Coupled Feed Loop PIFA
Performance Enhancement with Artificial Magnetic Conductors
• PEC Ground– Reflects Half the Radiation
• Gain can be increased by 3 dB
– Image Currents Can Cancel Currents in Antenna
• Limitation on distance between ground and radiating elements (/4)
– Reflection Coefficient of -1
PMC Ground– Image Currents In Phase with
Original Currents PMC is reflective Low Profile Antennas
– High Impedance Surface Current is filtered at selected
frequencies so tangential magnetic field is small while electric field is still large
Suppression of Surface Waves=>Minimizes Backlobe
– Reflection Coefficient of +1
Metamaterials
• Electrical Ground Plane Redirect one-half of the radiation gain can be increased by 3 dB Min. distance between antenna and ground : λ/4
• Image currents cancel currents in antenna poor radiation efficiency
• Metamaterials→Material that exhibit electromagnetic properties not found in nature
• EBG (Electromagnetic Band Gap) - Surface Subclass of metamaterials Can be designed to act as an AMC (Artificial Magnetic Conductor)
ground plane
ChallengesChallenges
Metamaterial
• Reflectivitiy “+1“ (reflection magnitude 1 and reflection phase 0°)• Can be achieved by utilizing periodic patch with via geometry or by planar
achitecture without the need of vias FSS (Frequency Selective Surface)• GA (Genetic algorithm) for an optimized FSS unit cell size,geometry and
dielectric constant and thickness of the substrate material
AMCAMC
Metamaterial - Simulations
FSS-designFSS-design
Unit CellUnit Cell
Antenna StructureAntenna Structure
FSS-Screen with AntennaFSS-Screen with Antenna
GA-Output ParameterGA-Output Parameter
Metamaterial – Simulations (cont‘d)
• Resonance frequency is decreasing by using a FSS-layer
Input Impedance- Comparison (with and without using an FSS-layer)Input Impedance- Comparison (with and without using an FSS-layer)
Metamaterial – Simulations (cont‘d)
• Higher Power transfer for the case with the FSS-layer (~94 % instead of 83 %)
• Directivity is alternating in the range between 900 and 950 MHz around 1.2
• Antenna could be made smaller future work
• Bandwidth sligthly smaller for the FSS-case
Bandwidth and maximum Directivity - Comparison Bandwidth and maximum Directivity - Comparison (with and without using an FSS-layer)(with and without using an FSS-layer)
Metamaterials (cont‘d)
• Using an FSS-layer drop the resonance frequency• Changing the size of the antenna to get a desired input impedance is
very difficult • Directivity behaviour changes sligthly• Higher power delivered to the antenna with the FSS-layer• Bandwidth slighly smaller for the FSS-case
Summary
Future work
Increasing Bandwidth Changing structure of the AMC instead of the antenna size Antenna attached to metal objects Performance will change Tunable antenna design provide tolerance for fabrication
Fabrication of AMCs
Configuration of AMC
GA Input
Parameter Output
FSS Layer
FSS Unit Cell
/2 x /2 FSS Layer
Reflection Crosses 0 at 939 MHz
Directivity AMC
Directivity
867 MHz 940 MHz
PEC Ground
2.5255 2.6126
AMC Ground
2.892 3.125
Increased 0.3665 0.5124
Directivity
915 MHz 940 MHz
PEC Ground
2.7074 2.421
AMC Ground
3.6855 2.9899
Increased 0.9781 0.5689
Dual-Band PIFA Inductively Coupled PIFA
Radiation [867 MHz]AMC
Dual-Band PIFA
Inductively Coupled PIFAPEC
PEC
AMC
AMC
Optimization Dual-Band PIFA Design
Impedance Stub 2.8
0
50
100
150
200
250
850 855 860 865 870 875 880 885 890 895 900 905 910 915 920 925 930 935 940 945 950
Frequency [MHz]
[]
Imaginary Gap 2.6 Imaginary Gap 2.5 Imaginary Gap 2.4 Imaginary Gap 2.2 Imaginary Gap 2.1
Real Gap 2.6 Real Gap 2.5 Real Gap 2.4 Real Gap 2.2 Real Gap 2.1
Optimization Dual-Band PIFA Design
STUB 2.8 Imaginary 867 MHz []
Real 867 MHz []
Power 867 MHz [%]
Gap 2.6 157.45 40.29 63.56
Gap 2.5 142.94 3.55 29.90
Gap 2.4 153.95 26.54 77.39
Gap 2.2 131.14 2.66 10.70
Gap 2.1 128.29 2.69 9.23
Note: 915 MHz and 940 MHz were not able to be sufficiently matched.
Optimization Inductively-Coupled Feed Loop PIFA Design
Impedance (Imaginary)
150
155
160
165
170
175
180
900 905 910 915 920 925 930 935 940 945 950
Frequency [MHz]
[]
Gap 9.5 Gap 9.4 Gap 9.3 Gap 9.25 Gap 9.2 Gap 9.1 Gap 8.9
Dimension [mm]
Imaginary 915 MHz
[]
Real 915 MHz
[]
Imaginary 940 MHz
[]
Real 940 MHz
[]
Power 915 MHz
[%]
Power 940 MHz
[%]
8.90 164.15 0.07 169.24 3.27 0.92 17.11
9.10 164.23 0.06 170.52 4.52 0.78 20.97
9.20 162.70 0.24 166.82 1.47 3.64 9.68
9.25 166.60 2.98 171.89 0.51 26.83 2.44
9.30 158.90 0.14 163.86 1.29 3.11 10.70
9.40 163.04 0.13 167.28 4.80 1.90 26.83
9.50 163.52 0.17 168.06 4.42 2.34 23.91
Optimization Inductively-Coupled Feed Loop PIFA Design
OBSERVATIONS
• Dual-Band PIFA Design showed to be platform tolerant in numerous cases
• Inductively Coupled Feed Loop PIFA was very sensitive to platform• An optimization was done for each mounting material with the
Inductively Coupled Feed Loop PIFA• The AMC ground plane did significantly improve the directivity and
reduce the backlobe in both antenna cases• An optimization needed to be done using the AMC for both antenna
cases because the impedance was altered• The Dual-Band PIFA Design was optimized to sufficient operation
but the Inductively Coupled Feed Loop PIFA was not
ALTERNATE PLATFORM-TOLERANT RFID DESIGNS
*courtesy of Prof. K.W.LeungCity University of Hong Kong
RFID Tag Design
- Background Information
•Inductive-coupled feeding design
Platform Tolerant
•Principle
-Using a patch antenna as the resonating element -The Tag antenna and the surface material are isolated by the ground plane
-The Tag has a stable performance regardless of the mounting surface
RFID Tag Antenna Configuration
First Design
Size of Ground Plane:Size of Ground Plane: 83.638 x 112.058mm (0.26λx 0.34λ)83.638 x 112.058mm (0.26λx 0.34λ)
Size of Printed Antenna:Size of Printed Antenna: 64.4 x 89.95mm(0.2λ x 0.27λ)64.4 x 89.95mm(0.2λ x 0.27λ)
Substrate thickness:Substrate thickness: 1.524mm1.524mm
Substrate dielectric constant:Substrate dielectric constant: 3.383.38
Substrate loss tangent:Substrate loss tangent: 0.00210.0021
RFID Tag Antenna Configuration
•Chip Impedance- 20.83 – j116.67ΩΩ
•Transmitted power of the Reader - 1W (30dBm)
•Gain of the Reader antenna- ~7.5dBi
RFID Tag Antenna Configuration
Simulated Antenna Gain
•Gain: ~ -8.6 to -0.77 dBi
RFID Tag Antenna Configuration
Current Distribution (First Design)
902 MHz
RFID Tag Antenna Configuration
Current Distribution (First Design)
915 MHz
RFID Tag Antenna Configuration
Current Distribution (First Design)
928 MHz
Result and Analysis
Measurement Method
-The Read Range was measured in the EMC Chamber
-Reader Antenna was moved inside the EMC Chamber
-Measure the maximum readable distance that the signal can be detected
RFID Tag Antenna Configuration
Measurement Method
- - RFID Tag was fixed by the foam stand and measured at different orientation angles (0 deg, 45 deg, 90 deg)
0 deg 45 deg 90 deg
Result and Analysis
Tag Antenna Configuration (by inductively-coupled feeding)
-The tag has similar performances for different angles
Result and Analysis
Second Design
-A Philips’s chip SL3S10 01 FTT is used
-Impedance of the chip: 16 – j380Ω (much more capacitive)
-Difficult to match using the first design
-Introduce a new feed network
RFID Tag Antenna Configuration
Second Tag Antenna Design
- - Directly connect the feed network to the radiating patch at several point
Size of Ground Plane: 83.638 x 112.058mm (0.26λx 0.34λ)Size of Ground Plane: 83.638 x 112.058mm (0.26λx 0.34λ)
Size of Printed Antenna: 54.45 x 93.3mm(0.17λ x 0.28λ)Size of Printed Antenna: 54.45 x 93.3mm(0.17λ x 0.28λ)
RFID Tag Antenna Configuration
Current Distribution (Second Design)
902 MHz
RFID Tag Antenna Configuration
Current Distribution (Second Design)
915 MHz
RFID Tag Antenna Configuration
Current Distribution (Second Design)
928 MHz
Result and Analysis
Platform Tolerance Test
-Following surfaces were used in the test:
-Acrylic (200 x 200 x 3 mm)
-Wood (200 x 200 x 3 mm)
-Aluminium (200 x 200 x 3 mm)
Result and Analysis
Platform Tolerance
-The tag has stable performance over different surfaces-The longest read range is obtained for the metal (Aluminium)
case because EM wave is reflected by the metal