Design of Rectangular Microstrip Antenna with EBG for multiband operations

Transcription

1 Design of Rectangular Microstrip Antenna with EBG for multiband operations Savita.M.S 1, Vani R.M 2, Prashant R.T 3, and Hunagund P.V 4 1 Research scholar Dept. of Applied Electronics, Gulbarga University, Gulbarga , Gulbarga, India 3 Professor and Head of University science and instrumentation Center Gulbarga University, Gulbarga , Gulbarga, India Abstract This paper presents design and development of rectangular microstrip antenna for multiband operation using low cost substrate material realized from conventional rectangular microstrip antenna. The proposed antenna is a novel geometry consisting of swastikebg cells on the ground plane of a rectangular microstrip antenna. The antenna uses the feed line same as that of the conventional rectangular microstrip antenna. The antenna operates in the frequency range of 1 to 14 GHz and gives an overall bandwidth of 87.99%. This technique also enhances the gain to 2.32 db more than the gain of conventional rectangular microstrip antenna (MSA) and gives a virtual size reduction of 80%. This antenna may find applications in WLAN, WiMax and other wireless communication applications. Keywords: Rectangular microstrip antenna, sawstik Electromagnetic Band Gap (EBG), bandwidth, back lobe. 1. INTRODUCTION Antenna is very important component of communication system. An antenna is transducer which converts the electric signal into electromagnetic wave and vice versa. Due to light weight and planar structure and less fabrication cost microstrip antenna is best antenna [1]. The rapid development of wireless communication systems has increased the demand for compact microstrip antennas with high gain and wideband operating frequencies. Microstrip patch antenna has advantages such as low profile, light weight, conformal, simple realization process and low manufacturing cost. However, the general microstrip patch antennas have some disadvantages such as narrow bandwidth etc. Enhancement of the performance to cover the demanding bandwidth is necessary [2]. A microstrip patch antenna consists of a radiating patch on one side of a dielectric substrate and a ground plane on the other side. So the design of the patch and substrate directly affects the antenna results. Recently, several techniques have been proposed for overcoming the problem of surface waves. One of the effective methods which suits for the millimeter structures is to use photonic band gap structures. The idea of these structures was proposed by yablonovich for the first time. Using photonic band gap structures has become attractive for engineers and researchers working on antennas, electromagnetic and microwaves [3]. These substrates contain so called Photonic Crystals. Also known as electromagnetic band-gap (EBG) structures and electromagnetic band-gap materials (EBMs) are a class of periodic metallic, dielectric, or composite structures that exhibit a forbidden band, or band gap, of frequencies in which waves incident at various directions destructively interfere and thus are unable to propagate [4-5]. On the other hand, the EBG structures also reflect back a part of the energy that circulate along the substrate of the antenna, thus acting as reflecting walls across the antenna and thereby the cavity effect[5]. With elite rows of EBG structures, minus energy is reflected back and the parasitic effect becomes prevailing. This contributes to the significant enhancement in the bandwidths [6-7]. The 2-D EBG surfaces, have the advantages of low profile, light weight, and low fabrication cost, and are widely considered in antenna engineering. Two popular kind of 2-D EBG are mushroom-like EBG surface and uniplanar EBG surface. An important feature in the uniplanar EBG design is the removal of vertical vias. Thus, it simplifies the fabrication process and is compatible with microwave and millimeter wave circuits. There are several configurations of EBG structures according to their application in antenna [8]. In this paper, an Electromagnetic Band Gap periodic structure is used which swastik is shape in the ground plane of the microstrip patch antenna. From the experimental results it is clear that characteristics such as the bandwidth, gain of the antenna are improved by adding the Electromagnetic Band Gap structure on the ground plane. 2. ANTENNA DESIGN Figure1(a) shows the geometry of the proposed conventional MSA, where a low cost glass epoxy FR4 dielectric material with relative permittivity (εr) of 4.4 with thickness (h) of 1.6mm is chosen. The conventional MSA is designed for 6GHz with dimensions L and W radiating part, which is excited by simple 50 Ω microstrip feed having dimensions length Lf and width Wf using quarter wave length transformer of dimension length Lt and Wt for their impedance matching. The length Lg and Wg of the ground plane of the antenna is calculated by Lg=6h+L and Wg=6h+ W and all the dimensions are shown in table1.the photographic view of the MSA is as shown in Figure1 (b). Volume 3, Issue 5, May 2014 Page 127

2 The study is carried by loading the swastik EBG structure in the ground plane of the MSA. By keeping all the parameter of the radiating patch, constant, the antenna is feed by stripline fed as in MSA. The ground plane is replaced by the swastik EBG. The geometry of the MSA-swastikEBG is as shown in the figure2(a). The 8x8mm EBG structure with length of the slot (sl)=4mm, width of the slot (sw)=1mm, the gap between swastik EBG is g=8mm. The photographic view of the MSA-swastikEBG is as shown in Figure2 (b). The parameter of the swastik EBG is as shown in table2.the swastikebg structure prohibits propagation of electromagnetic waves in a certain frequency bands. This suppresses the surface waves and hence gives enhancement in the performance of the proposed antenna. Further the study is carried out by connecting center swastik EBG four arms to the adjacent swastika EBG arms. The geometry view of the MSAswastikEBG1 is as shown in the Figure3 (a).the photographic view of the MSA-swastikEBG is as shown in the figure3 (b). Figure4 shows the single enlarged unit of swastika EBG. Table1: Parameter of the proposed antenna Antenna part Parameters Size in mm Patch Length(L) Width(W) Microstrip Length(L f50) 6.18 Feed Width(W f50) 3.06 Quaterwave Length(L t) 4.92 Transformer Width(Wt) 0.5 Ground plane Length(Lg) 40 Width(Wg) 40 Volume 3, Issue 5, May 2014 Page 128

3 3. Experimental Results and Discussions Figure5 shows the variation of return loss versus the frequency of MSA. It is seen that, the antenna resonates at 5.99GHz.The percentage of experimental impedance bandwidth is calculated using the relation is given in Equation 1. Where, f2 and f1 are the upper and lower cut off frequency of the resonated band when its return loss reaches -10 db and fc is a centre frequency between f1 and f2. The impedance bandwidth of MSA is found to be 4.81%. Figure6 shows the variation of return loss versus frequency of MSA-swastikEBG. From this figure it is found that the antenna resonates at five modes of frequencies f1, f2, f3, f4 and f5 with their respective impedance bandwidths are BW1= 15.25% GHz, BW2 = 9.94%, BW3= 0.61%, BW4 = 14.80% and BW5 = 5.57% respectively. The gain of MSA is found to be db by using Electromagnetic band Gap structure technique the gain is increased to 11.21dB of MSA-swastikEBG By comparing the resonant frequency fr of MSA to MSA-swastikEBG it is found that the MSA-swastikEBG gives virtual size reduction of 80%. Figure7 shows the variation of return loss versus frequency of MSA-swastikEBG1. From this figure it is found that the antenna resonates at seven modes of frequencies f1, f2, f3, f4, f5,f5,f6 and f7 with their respective impedance bandwidths are BW1= 11.15% GHz, BW2 = 5.62%, BW3= 13.38%, BW4 =9.86%,BW5 = 4.41%, BW6 = 27.55%, BW7 = 16.02% respectively. The gain of MSA is found to be db by using Electromagnetic band Gap structure technique the gain is increased to 12.69dB of MSA-swastikEBG1.By comparing the resonant frequency fr of MSA to MSA-swastikEBG1 it is found that the MSA-swastikEBG1 gives virtual size reduction of 57.5%. The proposed antenna result is shown in table3. (1) Figure5 Variation of return loss versus frequency of MSA Figure6 Variation of return loss versus frequency of MSA-swastikEBG Figure7 Variation of return loss versus frequency of MSA-swastikEBG1 Volume 3, Issue 5, May 2014 Page 129

4 Table3:.Results of the proposed antennas Antenna No. of Bands Return loss (db) Reson. Freq. ( GHz) Bandwidth in MHz Bandwidth in (%)age Overall Bandwidth in (%)age Gain in db Size Reduction (%) MSA MSA-swastikEBG % MSA-swastkEBG % Figure8 shows the Radiation pattern of E-plane of the proposed antennas from the figure it is clear that side lobes of the MSAswastikEBG and MSA-swastikEBG1 is reduced when compared to the conventional MSA.Figure9 shows the H-plane radiation pattern of the proposed antenna MSA-swastikEBG and MSA-swastikEBG1 and compared with the MSA. Figure8 Radiation pattern of E-plane of MSA, MSA-swastikEBG and MSA-swastikEBG1 Figure9 Radiation pattern of H-plane of MSA, MSA-swastikEBG, and MSA-swastikEBG1 Volume 3, Issue 5, May 2014 Page 130

5 4. Conclusions From the detailed study it is clear that, the design and development of MSA for multibands operations is possible by modifying MSA to MSA-swastikEBG. The proposed antenna operates between the frequencies ranges from 1 to 14GHz, and gives an overall bandwidth of 87.91% and a increased in gain of 2.33dB when compared to the MSA and a virtual size reduction of 80% and shows back lobe reduction. The antenna MSA-swastikEBG1 operates between the frequencies ranges from 1 to 14GHz, This antenna may find applications in wireless local area network (WLAN), worldwide interoperability for microwave access (WiMax) and other wireless communication applications like Bluetooth and high performance radio local area network (HIPERLAN). Acknowledgments The authors thank the authorities of Dept. of Science & Technology (DST), Govt. of India, New Delhi, for sanctioning the Vector Network Analyzer under the FIST project to the Department of Applied Electronics, Gulbarga University Gulbarga. References [1] I.J.Bahl and P.Bhartia, Microstrip Antennas. 1980, Boston: Artech House. [2] Thakur o.p.1, Dwari s. and Kushwaha a.k Enhancement of Bandwidth by using Photonic Bandgap structure in Microstrip antenna International Journal of Computational Intelligence Techniques, Volume 3, Issue 2, 2012, pp [3] Ram Singh Kushwaha 1, D.K.Srivastava 2, J.P.Saini 3 A Design of H-shape Slot loaded Wideband Microstrip Patch Antenna International Journal of Electronics and Computer Science Engineering, V1N [4] Ali. Rostami_, Seyed Yousef. Shafieiyand Farid. Alidoust Aghdam Optimization of Microstrip Antenna Characteristics Using Photonic Band Gap Structure HCTL Open IJTIR, Volume 3,pp 1-9, May [5] H. F. Shaban, H. A. Elmikaty, and A. A. Shaalan Study the effects of Electromagnetic Band Gap (EBG) substrate on two patches Microstrip antenna Progress In Electromagnetics Research B, Vol. 10, 55 74, 2008.). [6] Gaurav Kumar Sharma1, Narinder Sharma2 Improving the Performance Parameters of Microstrip Patch antenna by using EBG substrate IJRET: International Journal of Research in Engineering and Technology, Volume: 02 Issue: 12 Dec-2013 pp [7] M.S. Alam, M.T. Islam and N. Misran Design Analysis of an Electromagnetic Band Gap Microstrip Antenna American Journal of Applied Sciences 8 (12): , [8] Gaurav Kumar Sharma, Narinder Sharma Analysis of a Rectangular Microstrip Patch Antenna with EBG Structures International Journal of Computer Applications ( ) Volume 84 No 13, December AUTHOR Savita M Shaka received her M Sc from the department of Applied Electronics from Gulbarga University, Gulbarga in the year 2006 and her M Phil from the same department in year Currently she is pursuing her Ph. D in the field of Microwave Antennas from the department of Applied Electronics, Gulbarga University, Gulbarga. Prashant R T received his M Sc from the department of Applied Electronics Gulbarga University, Gulbarga in the year He worked as a Project Fellow in the UGC sponsored Major Research Project during the year Currently he is pursuing his Ph. D in the field of Microwave Antennas from the department of Applied Electronics, Gulbarga University, Gulbarga. Vani R M received her B.E. in Electrical and Electronics from the B.I.ET., Davanagere and M.Tech in Industrial Electronics from S.J.C.E., Mysore, Karnataka. She has received her Ph.D in Applied Electronics from Gulbarga University, Gulbarga, India, in year She is working as Reader & Head, University Science Instrumentation Center, Gulbarga University, Gulbarga, since She has more than 85 research publications in national and international reputed journals/conference proceedings. She presented the research papers in National/ International conferences in India and abroad. She has conducted several courses, workshops for the benefits of faculties and field engineers. Her areas of interest are microwave antennas, PC based instrumentation, embedded controllers and Wireless communication. She has one UGC major research project to her credit. Volume 3, Issue 5, May 2014 Page 131

6 P. V. Hunagund received his M.Sc and Ph.D from the Dept. of Applied electronics, Gulbarga University, Gulbarga, in the year 1982 and 1992 respectively. He is working as professor and chairman of Applied Electronics department, Gulbarga University, Gulbarga. He has more than 25 research publications in national and international reputed journals, more than 85 research publications in international symposium/conferences. He presented the research papers in National/International conferences in India and abroad. He has guided many Ph.D and M.Phil students. He has three major research projects at his credit. Volume 3, Issue 5, May 2014 Page 132