-
MODIFIED OPEN STUB MULTI-RESONATOR BASED CHIPLESS RFID TAG
Dinesh R*1, Anila P V,2Nijas C M3, Sumi M4 and P Mohanan5
1 2 3 4 5Centre for Research in Electromagnetics and Antennas
(CREMA), Department of Electronics, Cochin University of Science
and Technology, Cochin-22, Kerala, India
[email protected], [email protected],
[email protected],[email protected],
[email protected]
Abstract
A planar, fully printable, frequency signature based
multi-resonator circuit for chipless RFID transponder system and
swipe card is presented. The amplitude and/or group delay of the
spectral signature are utilized for the chipless tag or swipe card
multi-resonator circuit, providing a 1: 1correspondence of data
bits. It comprises of a bifurcated microstrip transmission line
meeting at the far end within which the open circuited shunt stub
multi-resonators are positioned. The developed structure can be
used effectively as a swipe card. The application of the proposed
circuit together with its cross-polarized transmitting and
receiving microstrip ultra-wideband disc loaded monopole antennas
for RFID transponder system is also presented. The experimental and
simulated results in support of the potentials of the chipless tag
for low cost item tagging such as bank notes and secured documents
are explained in this paper. The circuit is having high quality
factor and has a very small footprint of 24x10mm2.
Index Terms:—RFID,chipless Tag, Multi-Resonator
1. Introduction
Radio Frequency Identification (RFID) is a powerful enabling
technology with ever widening application. The primary potential of
the most promising chipless RFID tag is that they could be
eventually printed as a miniaturized circuit on a low loss
substrate which can replace trillions of barcodes yearly with
something far more versatile and reliable. A new idea of using
identical arrays of capacitively tuned microstrip dipoles for
different frequency for a passive low cost RFID tag is explained in
[1]. Engheta et.al in [2] demonstrates the development of RFID tag
by placing the space-filling curve inclusions in an array and
scaling each element within the array such that each element has
its own separate resonant frequency. A spectral signature based tag
using spiral multi-resonator circuit for short range application is
presented in [3, 5]. The paper [4] describes the use of microstrip
open stub resonators for compact chipless RFID tag.
The paper explains a simple planar multi-resonator circuit for
chipless RFID tag based on spectral signature encoding technique
and its application as swipe card and RFID transponder. It encodes
data into the spectrum using the resonant structures and hence
having a unique ID. The spectral signatures are created by the
multi-resonating circuit which act as multi stop band filters. The
proposed circuit is having high quality factor and is very compact
compared to other circuits, having only a footprint of 24x10mm2
dimension. The number of data bits can be increased by adding more
number of resonators without any considerable change in overall
dimension of the circuit.
2. Geometry
The structure comprises of a bifurcated microstrip transmission
line meeting at the far end within which the open circuited shunt
open stub multi-resonators are positioned. The open circuited shunt
stub resonator is very attractive for band notch action due to its
high Q-factor and simple structure. The multi-resonator encodes
data in their resonant frequencies. The geometry of the proposed
multi-resonator fabricated on a substrate of dielectric constant
3.7 and loss tangent 0.003 is given in Fig.1.
Considering each resonator, it will work as an open stub shunt
resonator. The equivalent circuit of an open stub resonator is a
parallel L-C tank circuit as shown in Fig.2, which offers high
impedance at its resonance, the resonance is known as
anti-resonance. Each resonance is due to the corresponding open
stub resonator, which is connected to the microstrip line at one
end and the resonant frequencies are determined by the length of
each stub. Each resonator is independently resonating at its
quarter wavelength frequency (λg/4) where λg is the guided
wavelength. The resonator exhibits high quality factor due to high
inductive reactance which avoids the merging of nearest resonant
frequencies.
978-1-4673-5225-3/14/$31.00 ©2014 IEEE
-
Fig.1. Geometry of Multi-Resonator circuit (L=24mm, W=10mm,
h=1.6mm, εr=3.7, tanδ=0.003)
Fig.2. Geometry of a single resonator with its equivalent
circuit (L=24mm,W=10mm)
3. Results and Discussion
The resonant frequencies of the prototype resonators (having
total physical dimension 2.4cmX1cm when fabricated on a substrate
of permittivity 3.7, loss tangent 0.003 and height 1.6mm)
corresponding to each resonator is given in Table.1 and the
physical lengths corresponding to each resonator are also given in
the same table.
Table 1: Resonant frequencies of Resonators
Resonator Physical
dimension(mm)
Resonant Frequency(GHz)
1 18 2.443 2 17.5 2.730 3 16 3.003 4 15 3.200 5 14 3.392 6 13
3.520 7 12 3.860 8 11 4.300 Spacing between each resonator
=0.5mm
Width of each resonator element=0.3mm
The tag encodes its spectral signature into the interrogation
signal spectrum using the above multi-resonating
circuit which is a multi-stop band filter. The stop band
resonances introduce magnitude attenuation and phase jumps to the
transmitted interrogation signal at their resonant frequencies
which are detected as abrupt amplitude attenuations and phase
jumps. The equivalent model of the multi-resonator circuit with its
equivalent parameters is shown in Fig.3. The simulated and measured
transmission parameter of the multi-resonator along with its group
delay is shown in Fig.4 and
-
Fig.5. All the measurements are done using PNA E8362B Network
Analyzer and simulations are done using Ansoft HFSS. The input
impedance is also plotted and is shown in Fig.6.
Fig.3 Equivalent circuit model of multi-resonators
Fig.4. Measured Transmission Parameter and Group Delay Fig.5.
Simulated S21(dB)
Fig.6. Impedance of the Multi-resonator
For a chipless RFID tag, a disc monopole UWB antenna has been
used as the receiving and retransmitting antenna.The geometry of
the monopole antenna along with the design parameters and its
reflection characteristics is depicted in Fig.7. The bistatic RFID
measurement set up with the UWB monopole antenna in the anacheoic
chamber and the measured transmission parameter and group delay are
presented in Fig.8.
-
Fig.7. Structure and reflection characteristic of the UWB
monopole antenna (R = 15mm, W3 = 3mm, Lg = 0.6mm, Lg1 = 40mm and
Lg2 = 20mm)
Fig.4. Measurement Set up and measured Transmission Parameter
and Group Delay
4. Conclusion
A novel fully printable multi-resonator circuit for chipless
RFID tag is fabricated and its characteristics are analyzed. The
structure is simple, compact and easy to fabricate and is based on
open stub multi resonating structure. The multi-resonator circuit
can be extended for any number of bits by incorporating additional
resonators. Replacing the disc monopole antenna with other compact
UWB antenna we can make RFID tag even smaller. The proposed RFID
tag is a promising candidate for the newly developed near field
identification, tracking and security applications.
5. References
[1]. I. Jalaly and I. D. Robertson, “Capacitively Tuned Split
Microstrip Resonators for RFID Barcodes," 2005 European Microwave
Conference, France, vol. 2, pp. 5-6, Oct. 2005.
[2]. J. McVay, A. Hoorfar, and N. Engetha, “Space flling curve
RFID tags,"2006 IEEE Radio and Wireless Symposium, San Diego, USA,
vol. 2,pp. 199-202, Jan. 2006.
[3]. S. Preradovic, S. Member, I. Balbin, N. C. Karmakar, S.
Member, and G. F. Swiegers, “Multiresonator-Based Chipless RFID
System for Low-Cost Item Tracking," IEEE Transactions on Microwave
Theroy and Techniques, vol. 57, no. 5, pp. 1411-1419, May 2009.
[4]. C. M. Nijas, R. Dinesh, U. Deepak, A. Rasheed, S. Mridula,
K. Vasudevan, and P. Mohanan, “Chipless RFID Tag Using Multiple
Microstrip Open Stub Resonators," IEEE Transactions on Antennas and
Propagation, vol. 60, no. 9, pp. 4429-4432, Sep. 2012.
[5]. Stevan Preradovic, Isaac Balbin, Nemai C. Karmakar and
Gerry Swiegers,” A Novel Chipless RFID System Based on Planar
Multiresonators for Barcode Replacement”, Procee. of IEEE
international Conference on RFID, pp. 289-296, April 2008
/ColorImageDict > /JPEG2000ColorACSImageDict >
/JPEG2000ColorImageDict > /AntiAliasGrayImages false
/CropGrayImages true /GrayImageMinResolution 200
/GrayImageMinResolutionPolicy /OK /DownsampleGrayImages true
/GrayImageDownsampleType /Bicubic /GrayImageResolution 300
/GrayImageDepth -1 /GrayImageMinDownsampleDepth 2
/GrayImageDownsampleThreshold 2.00333 /EncodeGrayImages true
/GrayImageFilter /DCTEncode /AutoFilterGrayImages true
/GrayImageAutoFilterStrategy /JPEG /GrayACSImageDict >
/GrayImageDict > /JPEG2000GrayACSImageDict >
/JPEG2000GrayImageDict > /AntiAliasMonoImages false
/CropMonoImages true /MonoImageMinResolution 400
/MonoImageMinResolutionPolicy /OK /DownsampleMonoImages true
/MonoImageDownsampleType /Bicubic /MonoImageResolution 600
/MonoImageDepth -1 /MonoImageDownsampleThreshold 1.00167
/EncodeMonoImages true /MonoImageFilter /CCITTFaxEncode
/MonoImageDict > /AllowPSXObjects false /CheckCompliance [ /None
] /PDFX1aCheck false /PDFX3Check false /PDFXCompliantPDFOnly false
/PDFXNoTrimBoxError true /PDFXTrimBoxToMediaBoxOffset [ 0.00000
0.00000 0.00000 0.00000 ] /PDFXSetBleedBoxToMediaBox true
/PDFXBleedBoxToTrimBoxOffset [ 0.00000 0.00000 0.00000 0.00000 ]
/PDFXOutputIntentProfile (None) /PDFXOutputConditionIdentifier ()
/PDFXOutputCondition () /PDFXRegistryName () /PDFXTrapped
/False
/CreateJDFFile false /Description > /Namespace [ (Adobe)
(Common) (1.0) ] /OtherNamespaces [ > /FormElements false
/GenerateStructure false /IncludeBookmarks false /IncludeHyperlinks
false /IncludeInteractive false /IncludeLayers false
/IncludeProfiles true /MultimediaHandling /UseObjectSettings
/Namespace [ (Adobe) (CreativeSuite) (2.0) ]
/PDFXOutputIntentProfileSelector /NA /PreserveEditing false
/UntaggedCMYKHandling /UseDocumentProfile /UntaggedRGBHandling
/UseDocumentProfile /UseDocumentBleed false >> ]>>
setdistillerparams> setpagedevice