Your SlideShare is downloading. ×
A Novel Compact UHF RFID Tag Antenna Designed with Series ...
A Novel Compact UHF RFID Tag Antenna Designed with Series ...
A Novel Compact UHF RFID Tag Antenna Designed with Series ...
A Novel Compact UHF RFID Tag Antenna Designed with Series ...
A Novel Compact UHF RFID Tag Antenna Designed with Series ...
A Novel Compact UHF RFID Tag Antenna Designed with Series ...
Upcoming SlideShare
Loading in...5
×

Thanks for flagging this SlideShare!

Oops! An error has occurred.

×
Saving this for later? Get the SlideShare app to save on your phone or tablet. Read anywhere, anytime – even offline.
Text the download link to your phone
Standard text messaging rates apply

A Novel Compact UHF RFID Tag Antenna Designed with Series ...

1,020

Published on

Published in: Business, News & Politics
0 Comments
0 Likes
Statistics
Notes
  • Be the first to comment

  • Be the first to like this

No Downloads
Views
Total Views
1,020
On Slideshare
0
From Embeds
0
Number of Embeds
0
Actions
Shares
0
Downloads
20
Comments
0
Likes
0
Embeds 0
No embeds

Report content
Flagged as inappropriate Flag as inappropriate
Flag as inappropriate

Select your reason for flagging this presentation as inappropriate.

Cancel
No notes for slide

Transcript

  • 1. 1 A Novel Compact UHF RFID Tag Antenna Designed meander-line section { with Series Connected Open Complementary Split Ring y Port Resonator (OCSRR) Particles Benjamin D. Braaten Abstract—A novel compact planar antenna for passive UHF { radio frequency identification (RFID) tags is presented. Instead of x using meander-line sections, much smaller open complementary dipole arm (a) split ring resonator (OCSRR) particles are connected in series to create a small dipole with a conjugate match to the power m harvesting circuit on the passive RFID tag. The manufactured (prototype) OCSRR RFID tag presented in this paper has an v n antenna input impedance of 15.8+j142.5 Ω at a frequency of 920 MHz and a max read range of 5.48 m. This performance is Port 2 f d ro Port 1 achieved with overall tag dimensions of .036λ0 × .17λ0 where λ0 is the free space wavelength of 920 MHz. h c g Index Terms—Open Complementary Split Ring Resonators, RFID, meander-line, dipole and passive tag. (b) I. INTRODUCTION Locsrr The antenna is a major component in the design of passive Port 2 Port 1 UHF radio frequency identification (RFID) tags. Previously, meander-line antennas have been popular designs for compact passive UHF RFID tags [1]-[5]. Meander-line antennas are Cocsrr designed by bending the arms of a printed dipole at right (c) angles to create an electrically larger antenna in a smaller Fig. 1. (a) A meander-line antenna [7]; (b) the OCSRR particle; (c) area [6]. The resulting antenna is a dipole with square-shaped the equivalent circuit of the OCSRR particle. sections along each dipole arm (Fig. 1 (a)). The current on each vertical section (i.e., y-directed trace) of the dipole is in the opposite direction of the current on each adjacent vertical section. This results in a canceled far-field, thus, the radiation presented in [10]. This OCSRR BPF was implemented in of the meander-line antenna is mainly due to the horizontal coplanar waveguide (CPW) technology. The OCSRR particle sections. The behavior of the meander-line antenna in Fig. is shown in Fig. 1 (b) with the equivalent circuit shown in 1 (a) can be described from a parallel circuit point-of-view. Fig. 1 (c). The equivalent circuit of the OCSRR particle has An equivalent capacitance exists between the longer parallel the same equivalent circuit as each meander-line section in vertical traces, while the horizontal traces form an equivalent Fig. 1 (a). Thus, series connected OCSRR particles have the inductance. This results in a parallel LC-circuit representation same equivalent circuit as the series connected meander-line of each meander-line section [7]. Thus, each meander-line pole sections. can be thought of as several series connected parallel LC- The work in this paper presents the application of using circuits. Therefore, to achieve an inductive input impedance, these OCSRRs in a manner similar to the series connected the inductive part of each meander-line section needs to be meander-line sections in Fig. 1 (a). In particular, the particles dominant. This is especially important for electrically small of OCSRRs in Fig. 1 (b) are connected in series to form the antennas, because the input impedance can be capacitive [8]- printed dipole shown in Fig. 2. The newly proposed design [9]. shown in Fig. 2 performs well as an RFID tag antenna and There are two major advantages of using a meander-line has the following very useful characteristics: 1) very simple to antenna. First, an inductive input impedance can be achieved design; 2) very easy to manufacture; 3) only one conducting with overall dimensions that are a fraction of the source layer is required for normal operation thus avoiding compli- wavelength. Second, the meander-line antenna only requires cated structures to enhance the performance; 4) each OCSRR a single conducting layer. These two characteristics of an particle is much smaller than the meander-line sections in RFID antenna are very useful because it is usually desirable previously published designs; 5) this antenna has a gain that is to have a small RFID tag printed on a single substrate (i.e., larger than other published meander-line antennas; and finally adhesive materials) with a conjugate match to the passive 6) the design presented in this paper is up to 50% smaller than RFID integrated circuit (IC). Even though the meander-line commercially available tags with comparable read ranges. antenna has resulted in small printed antenna designs, a smaller antenna is still very desirable. This is because a smaller II. UHF RFID ANTENNA WITH SERIES RFID antenna can be used in many more applications and are CONNECTED OPEN COMPLEMENTARY SPLIT less costly to manufacture (less material). RING RESONATOR PARTICLES Recently, a novel band pass filter (BPF) using an open Other than the equivalent circuit in Fig. 1 (c), the OCSRR complementary split ring resonator (OCSRR) particle was presented in [10] was chosen for the design in Fig. 2 for
  • 2. 2 w Higgs-2 s k h q p port The proposed UHF RFID antenna using series connected Fig. 2. OCSRR particles. two major reasons. First, each particle can be printed on a single conducting plane. This is very useful because, as mentioned before, antenna designs for passive UHF RFID tags Fig. 3. The printed OCSRR RFID antenna on the prototype passive are usually printed on a single adhesive dielectric substrate. RFID tag (c = .59 mm, d = .55 mm, f = .66 mm, g = .63 mm, h = For example, the design presented in this paper is much .65 mm, k = .77 mm, m = 13.37 mm, n = 11.91 mm, p = 1.23 mm, less complex than the metamaterial-based designs presented q = .61 mm, ro = 3 mm, s = 4.11 mm, w = 55.54 mm, h = 11.91 in [11]-[18]. Even though the antenna designs presented in mm and v = .7 mm). [11]-[18] have promising results, the designs require complex ground structures, lumped elements and different materials to 150 perform well. Using these techniques could result in a costly Re(Z ) (Ω) Simulation and complicated RFID tag. Second, the inductance of the 100 in OCSRR particle is four times than that of the complementary Measured 50 split ring resonator (CSRR) [10]. This makes the OCSRR par- 0 ticularly useful for compact UHF RFID antennas because the 800 850 900 950 1000 input impedance of an electrically small antenna is capacitive. f (MHz) By using several of the OCSRR particles connected in series, Im(Z ) (Ω) the input impedance of an electrically small resonant antenna 400 could be made inductive, which will be a conjugate match 200 in to the input impedance of the power harvesting circuit in the passive IC on the RFID tag. 0 The inductance of each particle is created by the loop of 800 850 900 950 1000 conducting material that has a width of h in Fig. 1 (b) (i.e., f (MHz) the conducting loop between the two inner and outer ring slots). This conducting loop creates an electrical short between Fig. 4. Measured input impedance of the printed OCSRR antenna. ports A and B. The capacitance in the particle is between the inner conducting disk with radius ro and the surrounding outer conducting planes. These two structural features in the [19] was used to design the printed antenna on 1.36 mm of particle result in an equivalent inductance and capacitance FR-4 (ε = 3.7 measured and tan δ = .0011 measured). The connected in parallel. This resulted in the equivalent circuit in passive IC on the prototype RFID tag chosen was the Higgs- Fig. 1 (c) [10]. By connecting the OCSRR particles in series 2 by Alien Technologies [20]. For a center frequency of 920 and choosing a size of each particle were the inductance is MHz, the Higgs-2 IC has an input impedance of approximately dominant; a designer is able to produce a layout that resembles ZIC = 13.6-j142.8 Ω [20]. Thus, the printed antenna design a thick printed dipole with periodic ring slots along the length should be close to the conjugate of ZIC at 920 MHz. This of the dipole. Having the layout resembling a thick printed conjugate match requirement resulted in the printed design dipole has the added advantage of increasing the radiation shown in Fig. 3. The size of each particle was determined resistance and bandwidth [9]. This is very useful for matching experimentally in Momentum. The simulated and measured1 the real part of the input impedance of the antenna to the power input impedance results agreed well and are shown in Fig. 4. harvesting circuit, especially because the input resistance of an The next step was to determine how well the prototype electrically small antenna is very low. RFID tag in Fig. 3 performed. The max read range of the tag was determined by attaching the tag to a piece of styrofoam. A. Experimental Results and Validation 1 To measure the input impedance, the printed antenna was cut symmetri- cally down the middle, placed vertically above a ground plane and fed with The first step was to design, manufacture and test a proto- an SMA connector through the ground plane. The input impedance was then type passive RFID tag with the antenna in Fig. 2. Momentum measured using a calibrated network analyzer.
  • 3. 3 OCSRR RFID tag OCSRR RFID tag plastic container Fig. 5. Measuring the max read range of the prototype OCSRR RFID Fig. 6. Measuring the max read range of the prototype OCSRR RFID tag in Fig. 3. tag in Fig. 3 on a plastic container. Then an Alien 9780 reader [20] and the prototype tag on the for larger values of ε. The results in Fig. 9 show a max gain styrofoam were placed in an anechoic chamber. The experi- of 1.93 dBi and that the gain reduces slightly for larger values mental test is shown in Fig. 5. The prototype tag was moved of ε. away from the reader antenna and a max read range of 5.48 m was determined. This max read range is much greater than the C. Results for various values of substrate thickness physically larger meander-line antenna presented in [5]. Then, Second, the thickness d of the substrate was changed. This the prototype tag was placed on a plastic container with a low illustrated how the input impedance and gain were affected by value of permittivity. This last test was performed to illustrate different values of d. The results from these simulations are the performance of the prototype tag on a manufactured item. shown in Figs. 10 - 12. The results in Fig. 10 show how the Again, the Alien 9780 reader and the plastic container were input resistance can increase substantially for larger values of placed in the anechoic chamber (Fig. 6). The max read range d and Fig. 11 shows that the antenna becomes more inductive was then determined to be 5.33 m. (i.e., resonates at a lower frequency) for larger values of d. The good results in Fig. 4 and the large read range values The results in Fig. 12 show a max gain of 1.86 dBi and that of the prototype tag indicate that Momentum is an excellent the gain can be significantly reduced for larger values of d. and precise tool for modeling the antenna in Fig. 2. Therefore, because of the numerous designs in the next sections, Momen- tum will be used solely to calculate the input impedance and D. Results for various values of inner disk radius gain of a variety of printed OCSRR antennas. In particular, Next, the radius of the inner disk ro was varied. This Momentum will be used to calculate the input impedance and illustrated how the input impedance and gain were affected gain of the OCSRR antenna in Fig. 2 on various substrate by different values of ro . The results from these simulations permittivities, substrate thicknesses and with several values are shown in Figs. 13 - 15. The results in Fig. 13 show that the of ro (i.e., disk radius values). These results will then be input resistance varies less than an ohm for various values of followed with Figures showing the surface current on the ro , while Fig. 14 shows that the input reactance of the antenna OCSRR antenna and the far-field patterns. Investigating these only varies by a few ohms for ro approximately less than 2.6 problems extensively will demonstrate the behavior of the mm. Then, the capacitance between the inner disk and outer OCSRR antenna presented in this paper. This could be very conducting plane becomes more significant for ro ≥ 2.6 mm. useful for a designer because a short review of the following After this value, the input reactance begins to reduce much sections may determine if the OCSRR antenna presented in more rapidly. The results in Fig. 15 show a max gain of 1.89 this paper is suited for a particular application of a passive dBi and that the gain is mostly unaffected by the radius of the UHF RFID tag. inner disk. B. Results for various values of permittivity E. Surface currents and far-field patterns. First, the permittivity ε of the substrate was varied. This Finally, the surface currents and far-field patterns were illustrated how the input impedance and gain were affected determined. The surface currents on the OCSRR antenna are by different values of ε. The results from these simulations shown in Fig. 16. Notice the currents concentrated on the inner are shown in Figs. 7 - 9. The results in Fig. 7 show the rate conducting ring. The normalized far-field patterns for the x-z at which the input resistance increases for larger values of ε and y-z planes are shown in Figs. 17 and 18, respectively. The while Fig. 8 shows how the antenna becomes more inductive far-field patterns are similar to the patterns of a small dipole.
  • 4. 4 50 50 ε = 1.0, d = .787 mm ε = 4.25, d = .127 mm 45 45 ε = 2.2, d = .787 mm ε = 4.25, d = .787 mm 40 ε = 4.25, d = .787 mm 40 ε = 4.25, d = 1.57 mm ε = 5.8, d = .787 mm ε = 4.25, d = 3.14 mm 35 35 30 30 Re(Zin) (Ω) Re(Z ) (Ω) in 25 25 20 20 15 15 10 10 5 5 0 0 800 850 900 950 1000 800 850 900 950 1000 f (MHz) f (MHz) Fig. 7. Input resistance for various values of ε. Fig. 10. Input resistance for various values of d. 2000 2000 ε = 1.0, d = .787 mm ε = 4.25, d = .127 mm ε = 2.2, d = .787 mm ε = 4.25, d = .787 mm 1500 ε = 4.25, d = .787 mm 1500 ε = 4.25, d = 1.57 mm ε = 5.8, d = .787 mm ε = 4.25, d = 3.14 mm 1000 1000 Im(Zin) (Ω) Im(Zin) (Ω) 500 500 0 0 −500 −500 800 850 900 950 1000 800 850 900 950 1000 f (MHz) f (MHz) Fig. 8. Input reactance for various values of ε. Fig. 11. Input reactance for various values of d. 2 2 1.8 1.8 1.6 1.6 ε = 1.0, d = .787 mm 1.4 1.4 ε = 2.2, d = .787 mm 1.2 ε = 4.25, d = .787 mm 1.2 Gain (dBi) Gain (dBi) ε = 5.8, d = .787 mm 1 1 0.8 0.8 ε = 4.25, d = .127 mm 0.6 0.6 ε = 4.25, d = .787 mm 0.4 0.4 ε = 4.25, d = 1.57 mm ε = 4.25, d = 3.14 mm 0.2 0.2 0 0 800 850 900 950 1000 800 850 900 950 1000 f (MHz) f (MHz) Fig. 9. Gain for various values of ε. Fig. 12. Gain for various values of d.
  • 5. 5 15 14.8 14.6 14.4 14.2 Re(Zin) (Ω) 0 A/m 50 A/m 14 13.8 Fig. 16. Surface currents on the printed OCSRR antenna in Fig. 3 13.6 with ε = 3.7 and d = 1.36 mm.. 13.4 13.2 13 1 1.5 2 2.5 3 ro (mm) x−z plane 90 1 Fig. 13. Input resistance for various values of ro with ε = 4.25 and 120 60 |E | θ d = .787 mm. 0.8 |Eφ| 0.6 150 30 0.4 0.2 140 180 0 135 130 210 330 125 Im(Zin) (Ω) 120 240 300 270 115 110 105 Fig. 17. Normalized pattern in the x-z plane of the printed OCSRR antenna in Fig. 3 with ε = 3.7 and d = 1.36 mm. 100 1 1.5 2 2.5 3 ro (mm) Fig. 14. Input reactance for various values of ro with ε = 4.25 and d = .787 mm. y−z plane 90 1 |Eθ| 120 60 0.8 |Eφ| 2 0.6 1.8 150 30 0.4 1.6 0.2 1.4 180 0 1.2 Gain (dBi) 1 0.8 210 330 0.6 0.4 240 300 270 0.2 0 1 1.5 2 2.5 3 ri (mm) Fig. 18. Normalized pattern in the y-z plane of the printed OCSRR Fig. 15. Gain for various values of ro with ε = 4.25 and d = .787 antenna in Fig. 3 with ε = 3.7 and d = 1.36 mm.. mm.
  • 6. 6 III. DISCUSSION [2] G. Marrocco, “Gain-optimized self-resonant meander line antennas for RFID applications,” IEEE Antennas Wireless Propag. Lett., vol. 2, pp. Many noteworthy comments can be made about the new 302-305, 2003. results in Fig. 3, Fig. 5 and Figs. 7 - 18. [3] C. Calabrese, G. Marrocco, “Meander-slot antennas for sensor-RFID tags,” IEEE Antennas Wireless Propag. Lett., vol. 7, pp. 5-8, 2008. 1) The dimensions in Fig. 3 show that the OCSRR UHF [4] B. D. Braaten, R. P. Scheeler, M. Reich, R. M. Nelson, C. Bauer- RFID antenna presented in this paper is much smaller (55.54 Reich, J. Glower and G. J. Owen, “Compact Metamaterial-Based UHF mm X 11.91 mm or .036λ0 × .17λ0 ) than commercially RFID Antennas: Deformed Omega and Split-Ring Resonator Struc- tures,” Accepted for publication in the ACES Special Journal Issue available tags. on Computational and Experimental Techniques for RFID Systems and 2) The measurements shown in Fig. 5 demonstrate that Applications, 2009. the prototype tag in Fig. 3 has a max read range (5.48 m) [5] B. D. Braaten, G. J. Owen, D. Vaselaar, R. M. Nelson, C. Bauer-Reich, J. Glower, B. Morlock, M. Reich and A. Reinholz, “A Printed Rampart- comparable to other published and commercially available line antenna with a dielectric superstrate for UHF RFID applications,” passive RFID tags with twice the overall size. IEEE Int. Conf. on RFID, The Venetian, Las Vegas, NV, April 16-17, 3) In Figs. 7 and 10, it is shown how the radiation resistance 2008. [6] H. Nakano, H. Tagami, A. Yoshizawa and J. Yamauchi, “Shortening can be controlled with values of ε and d, respectively. ratios of modified dipole antenna,” IEEE Trans. Antennas Propag., vol. 4) In Figs. 8 and 11, it is shown how the antenna can AP-32, no. 4, pp. 385-386, Apr. 1984. [7] R. Bancroft, Microstrip and printed antenna design, Scitech Publishing, be designed to resonate at a lower frequency with larger Inc., Raleigh, NC, pp. 194-195, 2006. values of ε and d, respectively. These results are similar to [8] W. L. Stutzman and G. A. Thiele, Antenna Theory and Design, 2nd ed., the metamaterial-based antennas presented in [4]. John Wiley and Sons, Inc., New York, NY, 1998. [9] C. A. Balanis, Antenna Theory: Analysis and Design, 3rd ed., John 5) From the results in Figs. 9 and 12, it can be concluded Wiley and Sons, Inc., New York, NY, 2005. that the gain of the antenna can be increased using smaller [10] A. Velez, F. Aznar, J. Bonache, M. C. Valazquez-Ahumada, J. Martel values of ε and d, respectively. and F. Martin, “Open complementary split ring resonators (OCSRRs) and their application to wideband CPW band pass filter,” IEEE Microw. 6) The results in Figs. 13 and 14 show that the particle Wireless Comp. Letters, vol. 19, no. 4, pp. 197-199, Apr. 2009. inductance can be used effectively to match the input reactance [11] R. W. Ziolkowski and C.-C. Lin, “Metamaterial-inspired magnetic-based of the antenna with the reactance of the tag. UHF and VHF antennas,” Proc. IEEE Antennas Propag. Soc. Int. Symp. Dig., San Diego CA, USA, July 5-11, 2008. 7) The patterns shown in Figs. 17 and 18 are similar to a [12] C.-J. Lee, K. M. K. H. Leong and T. Itoh, “Composite right/left-handed small dipole and illustrate that the tag in Fig. 3 can be read transmission line based compact resonant antennas for RF module from many different angles. integration,” IEEE Trans. on Antennas Propag., vol. 54, no. 8, pp. 2283- 2291, August 2006. [13] Q. Liu, P. S. Hall and A. L. Borja, “Dipole with left handed loading with optimised efficiency,” EuCAP, Edinburgh UK, pp. 1-4, Nov. 11-16, IV. CONCLUSIONS 2007. A new compact UHF RFID tag antenna designed using [14] H. Iizuka and P. S. Hall, “Left-handed dipole antennas and their implementations,” IEEE Trans. on Antennas Propag., vol. 55, no. 5, series connected OCSRR particles was presented. The series pp. 1246-1253, May 2007. connected OCSRR particles were modeled in Momentum [15] M. A. Y. Abdalla, K. Phang and G. V. Eleftheriades, “A planar elec- and the simulated input impedance values were successfully tronically steerable patch array using tunable PRI/NRI phase shifters,” IEEE Trans. Microw. Theory Tech., vol. 57, No. 3, pp. 531-541, Mar. validated with measurements. The result was a compact UHF 2009. RFID tag with a read range of 5.48 m. This read range [16] F. J. Herraz-Martinez, P. S. Hall, Q. Liu and D. Segovia-Vargas, “Tunable was accomplished with an overall antenna dimension up to left-handed monopole and loop antennas,” Proc. IEEE Antennas Propag. Soc. Int. Symp. Dig., Charleston, SC, June 1-5, 2009. 50% smaller than commercially available RFID tags with [17] J. Dacuna and R. Pous, “Miniaturized UHF tags based on metamaterials comparable read ranges. Next, the properties of the substrate geometries,” Building Radio Frequency Identification for the Global and dimensions of the inner disk were varied. Each of these Environment, July 2007, [Online], www.bridge-project.eu. [18] M. Stupf, R. Mittra, J. Yeo and J. R. Mosig, “Some novel design for changes were modeled numerically in Momentum and the RFID antennas and their performance enhancement with metamaterials,” input impedance and gain was determined for the different Microw. Optical Tech. Lett., vol. 49, no. 4, pp. 858-867, February 2007. substrate and inner disk values. These simulations were done [19] Advanced Design System-ADS 2009, Agilent Technologies. [20] Alien Technologies, [online], www.alientechnologies.com. to illustrate the behavior of the novel OCSRR RFID antenna presented in this paper. Finally, the surface currents and far- field patterns were determined. The OCSRR antenna presented in this paper has a pattern similar to a small dipole. ACKNOWLEDGEMENTS The authors would like to thank Aaron Reinholz and Michael Reich, at the Center for Nanoscale Science and Engi- neering (CNSE), North Dakota State University, for supporting various aspects of this project. R EFERENCES [1] K. Finkenzeller, RFID Handbook:Fundamentals and Applications in Contactless Smart Cards and Identification, John Wiley and Sons, West Sussex, England, 2003.

×