A Triangular Patch Antenna for UHF Band With Microstrip Feed Line for RFID Applications

A Triangular Patch Antenna for UHF Band With Microstrip Feed Line for RFID Applications

Twinkle Kundu1 and Davinder Parkasp

1M.Tech. Student, 2Assoc. Prof, ECE Deptt.

Haryana College of Technology & Management, Kaithal, Haryana, India

Abstract

This paper presents a novel microstrip antenna fed by microstrip line for Radio Frequency Identification (RFID) applications. With the reasonable gain, low profile and coupled with cheaper material, the proposed antenna is suitable for RFID applications. Antenna has been designed and optimized to operate at UHF band (0.89 GHz) using IE3d electromagnetic simulator. The fundamental parameters such as return loss, gain, radiation pattern, current distribution and efficiency are obtained. A parametric study of proposed antenna has been carried out by varying some parameters. Simulation tool, based on method of moments has been used to analyze and optimize the antenna.

Keywords: U-shaped slot, Radio frequency identification (RFID), Microstrip line

1. Introduction

   In recent years, the radio frequency identification (RFID) has received wide spread attention in many services since it provides a convenient identification information, long reading range and fast reading speed. RFID has been an alternative identification technology to the barcode. This is an emerging technology gaining growing interest both from scientific and industrial communities [1-2] .A basic RFID system consist of a radio scanner unit called reader, and a set of transponder called tags [3]. The tag is a microchip combined with an antenna system in a compact package [4]. Compared with traditional bar code tag, the RFID tag can be read and written over a long distance with a very high data rates[5].RFID system provides an automatic means to identify physical

   Objects without the need for line-of-sight communication [6].

   The bands assigned for data transfer are-125 KHz,

   13.56 KHz, 869 MHz, 902-928 MHz, 2.45 GHz and

   5.8 GHz [7].Several papers have been published on RFID antennas for both active and passive tags including covered slot antenna design [8], circular patch antenna analysis [9],meander antenna optimization [10],planer inverted F antenna [11], folded dipole antenna [12] etc. However very few papers [13] provided an overview of criteria for RFID tag antenna design & an analysis of practical application aspects. At the same time, there exist many papers on practical analysis and design of particular classes of antennas used for other application [14-16].

   In this paper, a new triangular patch antenna with U shaped slots is presented which resonates at 0.89 GHz which is the operating band of RFID application. The antenna is constructed with the help of microstrip feed line. The antenna dimensions have been optimized using EM simulation tool. This paper is organized as follows: In section II, the geometry of proposed antenna is described in detail. Simulation results and parametric study are given in section III and IV respectively. The return loss, gain, VSWR, current distribution, antenna efficiency and radiation pattern of proposed antenna is shown. Finally the paper is concluded in section V.

2. Antenna Structure

   The geometry of microstrip fed patch antenna for RFID applications is shown in Figure 1. This antenna is designed on FR4 substrate with thickness (h) of 1.6 mm, dielectric constant ( r) of 4.4 and loss tangent 0.02.By properly adjusting the dimension of antenna and feeding structure the characteristics of the proposed antenna is improved. For getting UHF frequency band of antenna a U slot is cut. Optimized design parameters were found with the following dimensions: a=23.5 mm, b=49.9 mm, c=43.19 mm. The remaining antenna dimensions are given in figure 1.With the aid of simulation by IE3D Simulator which

   is based on the method of moment (MOM), the antenna is optimized. The details of simulated performance are described briefly in next section.

   VSW R

   10

   9

   8

   7

   VSWR

   6

   5

   4

   3

   2

   1

   Figure 1 : Structure of triangular patch antenna with U slot

   The proposed antenna was fabricated on FR4 substrate. Prototype fabrication is done using photolithography technology. A photograph of the fabricated prototype is shown in figure 2

   0

   0.5 1 1.5 2 2.5 3

   Frequency (GHz)

   Figure 4: VSWR of a Triangular Patch Antenna with U slot

   Antenna gain is a measure of directivity properties of antenna. The proposed antenna provides sufficient and appropriate gain required for operation in the RFID (0.89) band. Gain and efficiency of proposed antenna is shown in Figure 5 and figure 6 respectively. The gain of the proposed antenna is 1.2 dBi at 0.89 GHz. Simulation results indicate that the maximum antenna radiation efficiency is approximately 80.3 %.

   Total Field Gain Vs Frequency

   4

   2

   dBi

   0

   Figure 2: Photograph of triangular patch antenna with U slot

3. Simulation Results

   Return loss (S11) of proposed antenna at 0.89 GHz is shown in figure 3. This antenna covers the frequency bands from 0.87 GHz to 0.97 GHz and VSWR of 1.48 is obtained at 0.89 GHz ( figure 4 )

   -2

   -4

   -6

   0 0.5 1 1.5 2

   Frequency (GHz)

   Figure 5 : Gain of a Triangular Patch Antenna with U slot

   0

   -2

   -4

   Return Loss (dB)

   -6

   -8

   -10

   -12

   -14

   -16

   -18

   S-parameter display

   100

   Percentage (%)

   80

   60

   40

   20

   Efficiency Vs. Frequency

   0 0.5 1 1.5 2 2.5 3

   Frequency (GHz)

   Figure 3: Return Loss of a Triangular Patch Antenna with U slot

   0

   0 0.5 1 1.5 2 2.5 3

   Frequency (GHz)

   Figure 6 : Efficiency of Gain of a Triangular Patch Antenna with U slot

   The current distribution pattern shows that how much of the current is flowing in the proposed structure. Maximum current in the proposed antenna is 1587.9 (A/m) at 0.89 GHz. The 3D current distribution plot gives the relationship between the co-polarization (desired) and cross-polarization (undesired) components. It gives a clear picture as to the nature of polarization of the fields propagating through the patch antenna.

   Figure 7 : Current distribution of triangular patch antenna with U slot

   Simulated two dimensional radiation patterns for elevation and azimuth plane are shown in figure 8

   .These patterns are desirable for RFID applications. Three dimensional radiation pattern is obtained by combining elevation pattern and azimuth pattern. Figure 9 shows three dimensional radiation pattern of proposed antenna.

   Figure 8 : Simulated 2-D Radiation pattern of triangular patch antenna with U Slot

   0

   -2

   -4

   Return Loss(dB)

   -6

   c=40.19 mm c=46.19 mm

   c(proposed)=43.19 mm

   -8

   -10

   -12

   -14

   Figure 9 : Three dimensional view of triangular

   -16

   0 0.5 1 1.5 2 2.5

   Frequency (GHz)

   patch antenna with U slot

4. Parametric Study

   A parametric study has been carried out and it demonstrates that many parameters affect the performance of the proposed antenna. The parametric study is carried out by simulating the antenna with one geometry parameter slightly changed from the

   Figure 10 : Effect of parameter c on return loss and resonant frequency

   Table 4.1 shows the simulation results of return loss and resonant frequency

   reference design while all the other parameters are fixed. he simulated return loss of the proposed antenna as a function of frequency for different values of parameter c is shown in figure 10 . We can see from Figure, as we increase c from optimum value resonant frequency shift to lower value (0.86 GHz) and

   c (mm) Resonant frequency (GHz)

   Return Loss(dB)

   as we decrease c resonant frequency increases (0.95 GHz) and bandwidth will also increase (0.2 GHz). Table 1 shows the simulation results of return loss and resonant frequency.

   Figure 11 shows the effect of change in feed length of triangular patch .It can be seen from Figure, as we increase the feed length from optimized value the bandwidth will increases and the value of return loss in dB (-ve) will decreases and as we decrease the feed length from optimum value then bandwidth will increases and value of return loss in dB (-ve) will increases.

   40.19 0.95 -13.5

   46.19 0.86 -14.5

   43.19 0.89 -14.2

   0

   -2

   -4

   Return Loss

   -6

   -8

   -10

   -12

   Feed Length=8.8 mm Feed Length=5.8 mm

   Feed Length (proposed)=7.3 mm

   -14

   -16

   0 0.5 1 1.5 2 2.5

   Frequency (GHz)

   Figure 11 : Effect of feed length on return loss

5. Conclusion

   A new microstrip fed triangular patch antenna for RFID applications with U slots has been presented in this paper. The proposed antenna was designed and simulated with IE3D simulator which has resonant frequency of 0.89 GHz. By embedding U slot in radiating patch 80.3 % efficiency was achieved. The proposed antenna design fulfilled the requirements needed to operate in RFID UHF band. It provides appropriate return loss and gain characteristics.

6. Reference

Propagation Soc. Int. Symp., vol. 1, Jun. 2004, pp.97100.

1. P. R. Foster and R. A. Burberry, Antenna problems in RFID systems,in Proc. Inst. Elect. Eng. Colloquium RFID Technology, Oct. 1999, pp.3/13/5.

2. C. Peixeiro, Design of log-periodic dipole antennas, Proc. Inst. Elect.Eng.Microwaves, Antennas and Propagation, vol. 135, pp. 98102, Apr.1988.

   [1]	Finkenzeller, K., RFID Handbook: Fundamentals	[16]	S. Brebels, J. Ryckaert, B. Come, S. Donnay, W. D. Raedt, E. Beyne, and R. P. Mertens, SOP
   	and Applications in Contact-less Smart Cards and		integration and codesign of antennas, IEEE Trans.
   	Identification, 2nd edition, Wiley & Sons, 2003.		Adv. Packag., vol. 27, pp. 341351, May 2004
   [2]	Yang, L., A. Rida, M. M. Tentzeris, and A.
   	Mortazawi, Design and Development of RFID
   	and RFID-enabled Sensors on Flexible Low Cost
   	Substrates, Morgan & Claypool Publishers, 2009.
   [3]	Foster, P., and Burberry, R.: Antenna problems in
   	RFID systems. IEE Colloquium on RFID
   	Technology, London, UK, 1999, pp. 3135.
   [4]	Khadijah Kamarulazizi, Dr.Widad Ismail,
   	Electronic Toll Collection System Using Passive
   	RFID Technology, Journal of Theoretical and
   	Applied Information Technology,2010.
   [5]	Lingfeimo And Chunfang Qin, Tunable Compact
   	UHF RFID metal Tag Based on CPW open Stub
   	Feed PIFA antenna, Hindawi Publishing
   	Corporation International Journal of Antennas and
   	Propagation , 2012.
   [6]	Hend A. Malhat, Saber H. Zaiud-Deen,Kamal H.
   	Awadalla, Curved Dual – Band Dielectric
   	Resonator Tag Antenna for RFID Applications,
   	International Journal of Radio Frequency
   	Identification and Wireless Sensor Networks, 18
   	June 2011.
   [7]	M. Keskilammi and M. Kivikoski, Using text as a
   	meander line for RFID application, IEEE
   	AntennasWirel Propag Lett 3 (2004), 372374.
   [8]	S.-Y. Chen and P. Hsu, CPW-fed folded-slot
   	antenna for 5.8 GHz RFID tags, Electron. Lett.,
   	vol. 24, pp. 15161517, Nov. 2004.
   [9]	S. K. Padhi, N. C. Karmakar, C. L. Law, and S.
   	Aditya, A dual polarized aperture coupled circular
   	patch antenna using a C-shaped coupling
   	slot,IEEE Trans. Antennas Propag., vol. 51, no.
   	12, pp. 32953298, Dec.2003.
   [10]	G. Marrocco, Gain-optimized self-resonant
   	meander line antennas for RFID applications,
   	Antennas Wireless Propag. Lett., vol. 2, no. 21,
   	pp.302305, 2003.
   [11]	M. Hirvonen, P. Pursula, K. Jaakkola, and K.
   	Laukkanen, Planar inverted-F antenna for radio
   	frequency identication, Electron. Lett., vol.40, pp.
   	848850, Jul. 2004.
   [12]	Q. Xianming and Y. Ning, A folded dipole
   	antenna for RFID, in Proc.IEEE Antennas and

3. S. Weigand, G. H. Hu, K. H. Pan, and J. T. Bernhard, Analysis and design of broad-band single-layer rectangular U-slot microstrip patch antennas, IEEE Trans. Antennas Propag., vol. 51, no. 3, pp. 457468,Mar. 2003.