IJEEE, Vol. 1, Issue 4 (August, 2014)
e-ISSN: 1694-2310 | p-ISSN: 1694-2426
MICROSTRIP PATCH ANTENNA WITH CROSS-SLOT FOR UHF RFID HANDHELD READER APPLICATIONS 1
Neha Saini, 2Vijay Kumar
1,2
E.C.E Department, Punjab College of Engineering and Technology, Punjab, India 1
neha.saini22@gmail.com , 2nanovijay1@gmail.com
Abstract— This paper presents a microstrip patch antenna with cross-slot for UHF RFID handheld reader applications. A square patch with unequal length crossslot and diagonally symmetrical two circular and two square slots are used to acheive compact size. The coaxial feed is used to excite the proposed antenna. The 10dB return loss bandwidth and VSWR of proposed antenna are 15.5MHz (914.3-929.8) and 1.6 respectively. Index Terms— Microstrip Patch Antenna, Radio Frequency Identification, RFID Reader Antenna, Return Loss, VSWR (Voltage Standing Wave Ratio). I. INTRODUCTION It is an automatic identification technology. This technology provides wireless identification and tracking. This technology is more convenient than use of bar codes and optical scanners [1]. Because it can transmits data without contact and Line-Of-Sight. Thus, the tagged items can be identified within the field without regard to orientation or position to affixed tag. The information is sent to and read from RFID tags by the reader using radio waves. This allows for many items to be interrogated instanteounsly without manual manipulation of the items. The information is sent to and read from RFID tags using radio waves. A RFID system typically consists of Tag Reader Information Management System [2].
Figure 1 RFID System
A. Tag RFID tag is an electronic circuit that exchanges data with an RFID reader through radio waves. Tags are data carrying devices, so also called as transponder. RFID tag consists of two main parts: International Journal of Electrical & Electronics Engineering 30
Integrated circuit (IC) and Antenna. IC is used for processing and storing data as well as modulating and demodulating radio waves transmitted /received by antenna. Antenna receives the radio waves. Due to dynamically functionality of tags, information can be added, modified or stored on a tagged item. RFID Tags can be classified into three categories on the basis of communication between tag and reader and these are active RFID tag, semi active RFID tag and passive RFID tag [3]. B. Reader It is also called as an interrogator. The means of interrogation is a wireless and because the distance is relatively short, the line of sight between the reader and tag is not necessary. It contains an antenna to transmit information to the tag as well as receive information from tag. RFID reader can be active RFID reader and passive RFID reader on the basis of communication between tag and reader. RFID reader can also be classified based upon the application fixed RFID reader and mobile RFID reader [4]. C. Information Management System An RFID system can be interfaced to an IT platform for exchange of information. Sometimes the host system is needed to collect the data to convert into useful information for the end-user. To have its longer read range, higher data transmission rate as well as larger storage capacity, UHF system are gaining more popularity compared to low frequency (LF), high frequency (HF), systems. It is known that operating frequencies of each country varies from one another in UHF RFID system because it is not universal worldwide [5]. The frequency is from 840 MHz to 960 MHz with different sub-bands such as 902928 MHz for North-South America, 865-867 MHz for Europe and 840-955 MHz for Asia-Pacific region. In Asia-Pacific region, the UHF RFID frequency ranges from 840 MHz to 955MHz in different countries: China (840.5-844.5 MHz, 920.5-924.5 MHz), Japan (952-955 MHz), India (865-867MHz), Hong Kong (865-868 MHz, 920-925 MHz), Taiwan (920-928 MHz), Korea (908.5-910 MHz, 910-914 MHz), Singapore (866-869 MHz, 923-925 MHz), Australia (920-926 MHz), etc. [6]. In RFID system the reader antenna is the one of the important component. For handheld RFID reader applications the overall size of antenna should be small. www.ijeee-apm.com
In this paper, a microstrip patch antenna with cross-slot for UHF RFID handheld reader applications is proposed. It is a square patch antenna with cross-slot and diagonally symmetrically two circular and two square slots to achieve compact size. The simulation of proposed antenna is carried out in HFSS (High Frequency Structure Simulator) software. II. ANTENNA DESIGN The geometry of proposed microstrip patch antenna with cross slot is shown in figure 2. This antenna is fabricated on FR-4 substrate (loss tangent, δ=0.02; dielectric constant, εr = 4.4) with thickness 2mm. The size of ground plane is 55mm×55mm and it is a square patch antenna whose size is 50mm ×50mm with a cross slot Sx and Sy along the x and y axes respectively is introduced on patch. The diagonally symmetrically two circular slots C1 & C2 and two square slots S1 and S2 are also introduced on patch radiator to achieve compact antenna.
Figure 3 Proposed Microstrip Patch Antenna in HFSS
The detailed dimensions of proposed microstrip patch antenna is given below in table 1. Table1: Dimensions of Proposed Microstrip patch Antenna
Parameter
Value (mm)
Lg Wg Lp Wp Sx Sy W h C1 C2 S1 S2 Feed Position
55 55 50 50 46 48 1 2 Radius=5 Radius=5 x= 5, y= 5 x= 5, y= 5 x= -3, y= 3
III. RESULTS AND DISCUSSION The Simulation of proposed antenna is done in HFSS software. Figure 4 shows the return loss at 922.3MHz. The return loss at 922.3 MHz frequency is 20.6dB. The 10dB return loss bandwidth of proposed antenna is 15.5MHz (914.3MHz-929.8MHz) and shown in figure5. Figure 6 shows the VSWR plot and the value of VSWR is 1.6 at 922.3MHz. Figure 7 shows the radiation pattern of proposed antenna and it can be observed from the plot that the proposed antenna is a good radiator. Figure 8 shows the current distribution in simulated patch radiator at 920MHz. Figure 2 (a) Geometry of propose microstrip patch antenna (b) Side view of Antenna
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Figure 4 Simulated Return Loss Plot
Figure 7 Simulated Radiation Pattern
Figure 5 Simulated 10dB Return Loss Bandwidth Plot Figure 8 Current Distribution of Simulated Patch Radiator at 920 MHz
The resonant frequency, input impedance, Return loss, 10dB return loss bandwidth and VSWR are 922.3MHz, 50ohm, -20.6dB, 15.5MHz (914.3MHz929.8MHz) and 1.6 respectively. REFERENCES
Figure 6 Simulated VSWR Plot
IV. CONCLUSION A microstrip patch antenna for UHF RFID handheld reader applications is presented. This antenna is designed based upon the handheld applications. This antenna is suitable for RFID handheld reader applications. Slots on the patch radiator are used to achieve the compact size. The overall size of antenna is 55 × 55 × 2mm3.
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[1] Ran Liu, Yuan Yao, Youbo Zhang, Hongbin Ge, Wenjing Lee, Junsheng Yu, and Xiaodon Chen “Design of a novel circularly polarized annular-ring RFID tag antenna for metallic surfaces” IEEE conference on Microwave, November 2013, pp. 245-247. [2] Debiao Li, Jianxiong Li, Luhong Mao “A novel broadband RFID tag antenna mountable on metallic surface” IEEE International Conference on Control, Automation and System Engineering, July 2011, pp. 1-4. [3] Neha saini, Vijay Kumar, “A review on microstrip patch antenna for UHF RFID tag application mounted on metallic surface” International Journal of Electrical & Electronics Engineering, Vol.1, Issue2, April 2014, pp. 14-18. [4] Charu Sharma, Ritu Gupta, “Microstrip patch antenna for RFID handheld reader application –a review” International Journal of Electrical & Electronics Engineering, Vol.1, Issue 2, April 2014, pp. 19-23. [5] M. S. R. Bashri, M. I. Ibrahimy, S. M. A. Motakabber, “A planar Wideband inductively coupled feed patch antenna for UHF RFID tag” IEEE International www.ijeee-apm.com
Conference on RFID Technologies and Applications, September 2013, pp. 1-6. [6] Nasimuddin, Zhi Ning Chen and Xianming Qing, “Compact arc-shaped slotted circularly polarized microstrip antenna for RFID readers� IEEE International workshop on Antenna Technology, March 2011, pp. 340343.
E-mail: neha.saini22@gmail.com
AUTHORS First Author: Neha Saini, Pursuing M.Tech in Electronics and Communication Engineering Punjab College Of engineering and Technology. She has Completed B.Tech from Indo Global College of Engineering in 2011.Her area of interest is Wireless & Mobile Communication & Antenna.
Vijay Kumar, Ph.D. is working as Professor in the Department of Electronics and Communication Engineering at Punjab College of Engg. & Tech. , Lalru, Distt. SAS Nagar (Mohali). His Research area is Nanotechnology. He has published 36 research papers in National & International Journals. He is the reviewer of several reputed journals like IEEE, Journal of Chemical Engg. & Materials Science (JCEMS) etc. He has been sanctioned Research project of Rs. 15.6 Lacs by DST, Govt. of India, New Delhi and currently six research scholars leading to their Ph. D degree are working under his guidance. E-mail: nanovijay1@gmail.com
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