LCIS, 50 rue de Laffemas, BP 54, Valence Cedex 09, France

Transcription

1 LCIS, 50 rue de Laffemas, BP 54, Valence Cedex 09, France Slide 1

2 Outline Motivation Previous Works Principle of the method in this work Simulation Results Realization, Experimental Validation Reading system Concluding remarks Slide 2

3 Motivation RFID has many aspects Various Tag Families : - Traditionnal with IC chip and antenna - More robust as chipless solutions This work focuses on Chipless - Specifically designed to obtained a pre-determined signature. - Tags of Pre-defined shapes. In this case the signatures have to be determined. We consider the alphabets Are we able to identify a complete set of letters? Slide 3

4 Motivation (Cont.) " Chipless RFID : The missing tag between optical barcode and RFID Chipless configurations Chipless RFID Low Cost Better Reliability No R/W Capabability 64 bits Metallic Letter Low cost Better Reliability No R/W capabability Low coding capacity Visual & RF identification 4

5 Previous Works Using Text/Logo as Tag Antennas Source : M Keskilammi et al «Using Text as a Meander Line for RFID Transponder Antennas», I EEE A W P L, VOL. 3, 2004 Slide 5

6 Identification and Authentication of Metallic Letters Reflected Signal L detected Incident pulse LCIS Highly reflecting Slide 6

7 Plane wave Mettalic Letter Plane wave «illumination» Slide 7

8 Arial Fonts, 24 Simulation Parameters CST Microwave Studio Shapes drawn in AUTOCAD 2010 with the explore and imported into CST. Plane wave excitation. A Gaussian pulse is used as an incident wave. Open boundary conditions are used. Probes were set to record Electric field and RCS in farfield regime. Vertical & Horizontal Polarizations Slide 8

9 24mm E H Slide 9

10 Frequency Response Electrical Far-field Simulation for Letters C,E,G,S,Z using Vertical Polarization Slide 10

11 EM signatures This group comprises C, E, G, S, Z. Common property : higher electrical length when considered in vertical polarization. The surface currents take one continuous curved path. Sharp resonant peaks in the range 2-3 GHz. Alphabet C E G S Z Resonant frequency , Slide 11

12 Frequency Response For Both Polarizations Electrical Far-field Simulation Result for Letters A,H,N,O,U,V using Vertical, Horizontal Polarization Letters A,H,N,O,U,V have similar response for Vertical Polarization Using the Horizontal Polarization allows their discrimination Slide 12

13 Identification Frequency Table Electromagnetic Response Lookup table for 24mm Height alphabet using Vertical Polarization A B C D E F G H I J K L M , , N O P Q R S T U V W X Y Z Slide 13

14 Identification Frequency Table (cont.) Electromagnetic Response Lookup table for 24mm Height alphabet using Horizontal Polarization A B C D E F G H I J K L M Out 4, N O P Q R S T U V W X Y Z Min 7.5 Min Slide 14

15 Sample Realization 2.5mm 13mm 24mm 2.5mm 11mm 3mm Fabrication Process : Etching Substrate : Flexible Kapton, ε r =3.8, thickness = 0.1mm Slide 15

16 Setup for Frequency Measurement Complex RCS measurement (Radar Cross Section) Vector Network Analyser 20GHz Anechoic chamber S11 35cm Horn antenna 12dBi 35cm Letter Calibration Isolation measurement (remove reflection from surrounding object) Metallic plane measurement (remove antennas and cables effects) Slide 16

17 Frequency Response Measurements S11 Measurement Result for Letters C,Z,E,G using Vertical Polarization Slide 17

18 Frequency Response (Cont.) Measurements S11 Measurement for Letters S,C,X,R using Horizontal Polarization Slide 18

19 Reading System Pulse generator Time domain approach PA µp DSP ADC LNA F Detected " FCC UWB bandwidth : 3.1GHz to 10.6GHz " -41.3dBm/MHz => -2.5dBm mean power " Pulse repetition rate min 1MHz " Instantaneous peak power as high as 5W for 100ps pulse duration Slide 19

20 Reading System Behavior of 100ps Gaussian Pulse, with 1MHz repetition rate Not compliant Solution : modifying the pulse shape Slide 20

21 Reading System " «pulse shaping» to fit the FCC mask ECC not compliant ECC rules are more stringent than FCC rules for UWB ECC solution : two pulses Slide 21

22 Reading System Double pulse solution Slide 22

23 Conclusion " Letters are used for identification purposes " The 26 alphabet (Arial) metallic letters have been Simulated, Realized and Measured. " Using Both Vertical and Horizontal polarizations, all letters can be identified without any error. " The letter I can used as scaling Element " Measurement in Frequency domain shows a good agreement with simulation results " Possible time domain Reading System based on pulses, FCC and ECC compliant Slide 23

24 Example of Reading System 24 " Preradovic et al. Frequency domain approach Simple solution that works: 5 to 11GHz Not compliant to FCC and ECC rules

25 Setup for Time Measurement Complex RCS measurement (Radar Cross Section) Pulse generator 100ps DSO Agilent 13GHz, 40Gs/s RTS Pulse shape 2V 70ps syncro 50cm 50cm 50cm Horn antenna 12dBi -2.5dB Tag -15dB Slide 25

26 Some letters show higher resonances Alphabets C, E, G show peak at 8, 8.2 and 8.4 GHz. But alphabets S and Z do not show peak here. Infact they do show peak but in Y component of the E-farfield, This could be understood by the surface currents of one alphabet from each class Slide 26

27 Slide 27

28 Simulation Parameters Alphabets J, F and K have X component of E-farfield also because of the net current in X direction. F,K, T can be clearly distinguished. Only J and L have close response. We need to refine the approach to distinguish them. Slide 28