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© Kathrein RFID Dr. Iliev, CST UGM 2011 1
Embedded UHF RFID Transponder
into the Layout of a Printed Circuit Board
Dr. Stoyan IlievKathrein RFID
CST European User Group Meeting 2011 19 May 2011, Munich
© Kathrein RFID Dr. Iliev, CST UGM 2011 2
Outline
1. UHF RFID transponder theory
2. Murata MagicStrap types
3. Design of embedded transpondera. Import of existing layoutb. Assessment of recommended antenna designsc. CST based optimised design
4. Comparison of simulation and read range measurement
5. Conclusion
© Kathrein RFID Dr. Iliev, CST UGM 2011 3
1. UHF RFID transponder theory
Simplified transponder equivalent circuit Power delivered to the load
Transmission coefficient (TC)
),(42
12
0 Γ∆⋅= gRV
PA
L
Transmission coefficient:shows the amount of power delivered to the loadTC equals 0 (0%) – no power is transferred to the loadTC equals 1 (100%) – the available power is transferred to the load
© Kathrein RFID Dr. Iliev, CST UGM 2011 4
2. Murata MagicStrap® Types
Type1 Type2 Type3 Type4
Impedances at minimum operating power
MAGICSTRAP® Technical Data Sheet
SMD RFID module, which incorporates a standard ICand enables the traceability of PCBs
from the first manufacturing step
© Kathrein RFID Dr. Iliev, CST UGM 2011 5
3. Design of the embedded transponder
Import of existing PCB in ADS Layout
Simplifying the layout
Implementing the transponder structure into the PCB
Saving data for 3D EM
Import data in CST Microwave Studio
Simulation of transponder matching, far field characteristicsand optimization
Design steps
GoalTo obtain a high TC, not only for a single PCB, but also for the boards in a panel with multiple PCBs
© Kathrein RFID Dr. Iliev, CST UGM 2011 6
3.a Import of existing layout
Layout simplification
Import of .dxf data in ADS
Export data for 3D Simulation in CST
Interoperability between ADS Layout und CST Microwave Studio offers excellent exportand import capabilities
© Kathrein RFID Dr. Iliev, CST UGM 2011 7
3.b Assessment of recommended design
Port4.7+j157
Gain:3.73 dBi
For this particular PCB the TC is 17%
© Kathrein RFID Dr. Iliev, CST UGM 2011 8
Port311+j165
Port212+j166
Port15+j157
Transmission coeff.:43%
Transmission coeff.:47.55%
Transmission coeff.:18%
Port impedances of recommended antenna designs in a panel with multiple PCBs
The port impedances show rather good matching between Murata Chip and recommended antenna design
Nr.1
Nr.2
Nr.3
3.b Assessment of recommended design
© Kathrein RFID Dr. Iliev, CST UGM 2011 9
Nr.1
Nr.2
Nr.3
Nr.1 Nr.2
Nr.3
Gain 4dBi
Gain 4dBiGain 2.5dBi
Far field simulation
3.b Assessment of recommended design
© Kathrein RFID Dr. Iliev, CST UGM 2011 10
Port15+j175
Transmission coef.:67%
Gain:3.76 dBi
3.c CST based optimised design
© Kathrein RFID Dr. Iliev, CST UGM 2011 11
Port328+j186
Port231+j185
Port119+j182
Transmission coef.:93%
Transmission coef.:92%
Transmission coef.:84%
Nr.1
Nr.2
Nr.3
The goal is to provide good matching in the panel with multiple PCBsThis way a good read performance can be achieved at the production lines
3.c CST based optimised design
© Kathrein RFID Dr. Iliev, CST UGM 2011 12
Gain 3.9dBi
Gain 3.9dBiGain 2.6dBi
3.c CST based optimised design
Nr.1
Nr.2
Nr.3
Far field simulation
© Kathrein RFID Dr. Iliev, CST UGM 2011 13
4. Comparison simulation in MoM
Port324+j185
Port227+j187
Port118+j192
Transmission coef.:91%
Transmission coef.:94%
Transmission coef.:94%
The comparison of simulation results shows a good agreement
Nr.1
Nr.2
Nr.3
Transmission coefficientRecommended design
CST
Port 1 18%
Port 2 48%
Port 3 43%
Transmission coefficientOptimised design
CST MoM
Port 1 84% 94%
Port 2 92% 94%
Port 3 93% 91%
© Kathrein RFID Dr. Iliev, CST UGM 2011 14
4. Read range measurement
Recommended design
Optimised design
4 m 6.9 m
Read range based on 2 W ERP
© Kathrein RFID Dr. Iliev, CST UGM 2011 15
4. Selectivity with Ultra Low Range Antenna
Limited read range < 10 cm
Extremely high selectivity (typ. 5 cm )
Extremely low gain ( < -30 dBi)
Dimensions: 7 cm x 9 cm
High mechanical robustness (IP67)
Ideal for conveyor belts and access systems
No interference by metallic objects in the vicinity
The Ultra Low Range Antennareads selectively a single boardin a panel with multiple PCBs
Nr.1
Nr.2
Nr.3
Addresses only Nr.1 PCB
© Kathrein RFID Dr. Iliev, CST UGM 2011 16
5. Conclusion
CST Microwave Studio is a very good tool for embedding and analysing UHF RFID transponders in the layout of existing boards
The recommended designs from Murata show a relative good matching to chip impedances
The layout of a single board can be further optimised to match the chip impedance and achieve a greater read range
The Low Range Antennas ensure very high selectivity for addressing a single board in a panel with multiple PCBs