Design of omnidirectional linearly polarized hemispherical dra for

Design of omnidirectional linearly polarized hemispherical dra for

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  International Journal ofElectronics and Communication Engineering & Technology (IJECET), INTERNATIONAL JOURNAL OF ELECTRONICS AND ISSN 0976 – 6464(Print), ISSN 0976 – 6472(Online), Special Issue (November, 2013), © IAEME COMMUNICATION ENGINEERING & TECHNOLOGY (IJECET) ISSN 0976 – 6464(Print) ISSN 0976 – 6472(Online) Special Issue (November, 2013), pp. 261-268 © IAEME: www.iaeme.com/ijecet.asp Journal Impact Factor (2013): 5.8896 (Calculated by GISI) www.jifactor.com IJECET ©IAEME Design of Omnidirectional Linearly Polarized Hemispherical DRA for Wideband Applications Jitendra Kumar1, Navneet Gupta2 Department of Electrical and Electronics Engineering, Birla Institute of Technology and Science, Pilani, Rajasthan 333031, India 1jitu.kumar87@gmail.com, 2ngupta@pilani.bits-pilani.ac.in ABSTRACT: A multi segmented hemispherical dielectric resonator antenna (HDRA) centrally fed by coaxial probe for a broadband application is proposed. This paper discusses four segments of dielectric material separated by air gaps. This multi segmented HDRA achieves a 10-dB impedance bandwidth of about 80%, while covering the frequency range from 2.8 to 5.2 GHz with improved radiation pattern. This DRA radiates like an electric monopole and generates omnidirectional linearly polarized field. Ansoft HFSSTM is used to simulate the dielectric resonator antenna (DRA) performance and the results are verified with another 3-D EM solver CST-Microwave Studio. Both results are in close agreement with each other, which shows the validity of proposed design. KEYWORDS:Dielectric Resonator Antenna, Ultra Wideband, Omnidirectional, Linear Polarization I. INTRODUCTION In the past two decades, the DRAs have attracted the antenna designers in microwave and millimeter wave band due to its features like high radiation efficiency, light weight, small size, low profile, low temperature coefficient of frequency, zero conductor losses, wide impedance bandwidth and suitable scale in microwave band [1,2]. Dielectric resonators (DRs) of low loss dielectric material, having medium dielectric constant of 10< <20 are ideally suitable for antenna applications and compromise can be made between size, operating frequency and other antenna radiation characteristics. These antennas can also be easily integrated into portable communication devices [5]. Hemispherical shaped dielectric resonator (DR) is one of the most basic geometry of DRA. A variant of HDRA was introduced and characterized by D. Guha et al. [6] in which they had proposed four element quarter hemispherical geometry for DRA. However, the impedance bandwidth of proposed antenna is limited to 30%. In order to further improve the bandwidth and other radiation characteristics, multi segmented HDRA centrally fed by coaxial probe for broadband applications is proposed. This DRA design uses the conventional technique of the finite ground plane using Teflon (lossy) International Conference on Communication Systems (ICCS-2013) B K Birla Institute of Engineering & Technology (BKBIET), Pilani, India October 18-20, 2013 Page 261
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  International Journal ofElectronics and Communication Engineering & Technology (IJECET), ISSN 0976 – 6464(Print), ISSN 0976 – 6472(Online), Special Issue (November, 2013), © IAEME ( =2.1) as a substrate layer followed by the four segments of dielectric material separated by air gaps. An inexpensive Rogers R03210 (lossy)( =10.2) are used for segmented DR elements. Two resonant modes in four segments structure have been successfully exploited at 3GHz and 4.8GHz. (a) (b) Fig. 1: Four segmented HDRA: (a) Front view with different dimension, (b) Top view with four DR elements II. DESIGN AND OPTIMIZATION The antenna configuration and the geometry of the DRA are shown in Fig.-1. The fundamental modes are divided into two modes: TE111 and TM101. Antenna design simulated on the Ansoft HFSSTM [9] (based on finite element method) as well as on CST microwave studio [10] (based on the finite integration method). The theoretical resonant frequency and radiated Q-factor for fundamental modes is given as [12] = 4.7713 Re( r)/r (1) Where K0 is free space wave number and r is radius of the segmented hemisphere of DR elements in cm For TE111 Mode: Re( r) = 2.8316  . Q= 0.08+0.796 +0.01226 -3.10  For TM101 Mode: Re( r) = 4.47226  . For  < 20 Q = 0.723+0.9324 -0.0956 -0.00403 -5.10  For  > 20 Q = 2.621-0.547 +0.01226 -2.59*10  (2) (3) (4) (5) (6) A parametric study of the proposed DRA is carried out using Ansoft HFSSTM which is based on finite element method. The SMA connecter’s probe length was optimized using Ansoft HFSSTM for L= 9.1, 9.7, 10.3, 10.6, 10.9, 11.3, 11.6 and 11.9 mm from the upper layer of substrate and is International Conference on Communication Systems (ICCS-2013) B K Birla Institute of Engineering & Technology (BKBIET), Pilani, India October 18-20, 2013 Page 262
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  International Journal ofElectronics and Communication Engineering & Technology (IJECET), ISSN 0976 – 6464(Print), ISSN 0976 – 6472(Online), Special Issue (November, 2013), © IAEME shown in Fig. -2. It is observed that a very well optimized probe length at L=10. 9mm has a better impedance matching than another. Fig. 2: Reflection coefficient of Omnidirectional DRA as a function of frequency for different DRA’s Probe length of L=9.1, 9.7, 10.3, 10.6, 10.9, 11.3, 11.6 and 11.9mm from the upper layer of substrate The effect of the variation of radius (r) in the segmented hemispherical DR elements of the DRA is also studied and is shown in Fig.-3. It is found that as ‘r’ increases, the range of the reflection coefficientS11 decreases at 10-dB. Best optimized radius of DR elements is found at r=20mm. Fig. 3: Reflection coefficient of Omnidirectional DRA as a function of frequency for different radius r=20, 20.5, 21, 22, 23, 24 and 25mm of DR elements. The characteristic impedance of the antenna is controlled by the length of the probe line of SMA connector and height of the substrate. From the equations (1 to 5) and simulation results, the following observations were made for the best optimum dimensions of DRA:  Element#1= Element#2= Element#3= Element#4, all four DR elements have radius of r=20mm.  Air-gap (g) separator between the DR elements is 1mm. International Conference on Communication Systems (ICCS-2013) B K Birla Institute of Engineering & Technology (BKBIET), Pilani, India October 18-20, 2013 Page 263
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  International Journal ofElectronics and Communication Engineering & Technology (IJECET), ISSN 0976 – 6464(Print), ISSN 0976 – 6472(Online), Special Issue (November, 2013), © IAEME  The dielectric substrate is of 1mm thickness and 35mm in radius. Center fed probe of SMA connector is of length L=10. 9mm from the upper layer of substrate. III. RESULTS AND DISCUSSIONS The reflection coefficient curve of the antenna is shown in Fig.-4 that is simulated onAnsoft HFSSTM and CST microwave studio. The impedance bandwidth covers the frequency range from 2.8 GHz to 5.2 GHz approximate for S11< -10dB, and shows good agreement with the both results. An impedance bandwidth of 80% is obtained, which is wide enough for normal DRA applications. It is also observed that two resonances at 3 GHz and 4.8 GHz exist in the frequency band. Fig.4:Comparison to Return loss of DRA on Ansoft HFSSTM& CST microwave studio Fig. 5 shows the radiation pattern of DRA and it is observed that the proposed antenna has a very good omnidirectional pattern at 3GHz. (a) (b) Fig. 5: Omnidirectional gain at 3GHZ: (a) 3-D radiation Pattern, (b) Polar plot International Conference on Communication Systems (ICCS-2013) B K Birla Institute of Engineering & Technology (BKBIET), Pilani, India October 18-20, 2013 Page 264
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  International Journal ofElectronics and Communication Engineering & Technology (IJECET), ISSN 0976 – 6464(Print), ISSN 0976 – 6472(Online), Special Issue (November, 2013), © IAEME The proposed DRA is also studied for far field radiation pattern. Figure-6 shows the radiation pattern in polar form at two different frequencies (3GHz and 4.8GHz), here it is clear observed that the antenna radiation in the broadside direction also. (a) (b) (c)(d) Fig. 6: Gain of proposed antenna: (a) HFSS result at 3GHz, (b) CST result at 3GHz, (c) HFSS result at4.75GHz, (d) CST result at4.8GHz As proposed DRA has broadside radiation pattern, the antenna efficiency is estimated from the simulated far field gain. The proposed DRA achieves more than 98% antenna efficiency with most of the band. The radiation patterns obtained at two frequencies are shown in Fig. 7, which shows a set of representing the result of the gain verses theta angle for different values of Ø (phi). It is observed that instead of Ø =90 degree, the plane makes no difference from Ø =0 &45 degrees for both resonant frequencies of DRA. International Conference on Communication Systems (ICCS-2013) B K Birla Institute of Engineering & Technology (BKBIET), Pilani, India October 18-20, 2013 Page 265
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  International Journal ofElectronics and Communication Engineering & Technology (IJECET), ISSN 0976 – 6464(Print), ISSN 0976 – 6472(Online), Special Issue (November, 2013), © IAEME Fig. 7: Cartesian plot of Gain Vs Theta The results obtained from Ansoft HFSSTM were verified with another 3-D EM solver CST Microwave studio and results are tabulated in Table-1.So from the application point of view we can see the result obtained from both simulators are almost same. AnsoftHFSSTM CSTMicrowave Studio I II I II 3GHz 4.75GHz 3GHz 4.8GHz -15dB 24 dB -23dB -19 dB 1.01 4.38 0.8 4.2 131.4 43.1 125.1 53.7 98.8% 99.2 % 98.2% 97.5% 57dB 42 dB 40dB 40 dB Omnidirectional Linear Omnidirectional Linear Linear Slant Linear Slant Table 1: Comparison between different parameters of DRA obtained with Ansoft HFSSTM and CST Microwave Studio simulations Parameters Resonance Resonance Frequency Return Loss Gain (dB) Beam Width (Degree) Radiation Efficiency Axial Ratio Polarization IV. CONCLUSION The centrally probe fed omnidirectional linear polarized DRA has been studied and successfully design a multi segmented omnidirectional linear polarized wide band DRA. In this work a modified design of four segmented hemispherical DRA with enhanced bandwidth and improved radiation is achieved. In the proposed design the DR element is separated by air gap that results in the improvement of the bandwidth. The impedance bandwidth of this antenna is about 80% covering the frequency range from 2.8 to 5.2 GHz for reflection coefficient less than -10dB which is more than double compare to conventional HDRA. In comparison to conventional HDRA, this design significantly reduces the size of the antenna also. International Conference on Communication Systems (ICCS-2013) B K Birla Institute of Engineering & Technology (BKBIET), Pilani, India October 18-20, 2013 Page 266
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  International Journal ofElectronics and Communication Engineering & Technology (IJECET), ISSN 0976 – 6464(Print), ISSN 0976 – 6472(Online), Special Issue (November, 2013), © IAEME V. ACKNOWLEDGEMENT The authors would like to thank Mr. Amitesh Kumar, from the Society for Applied Microwave Electronics Engineering & Research (SAMEER), Kolkata, India for his help in getting simulation work reported in this paper. REFERENCES [1]K. M. Luk and K. W. Leunge, Dielectric Resonator Antenna, (Eds. Baldock, U.K: Research study press limited, London, 2003). [2]S. A. Long, M. W. McAllister, and L. C. Shen, The resonant cylindrical dielectric cavity antenna, IEEE Trans. Antennas Propaga, 31(5), 1983, 406–412. [3]P. Rezaei, M. Hakkak and K. Forooraghi, Design of wide band dielectric resonator antenna with two segment structure in Progress In Electromagnetic Research, PIER 66, 2006, 111-124. [4]A.Petosa, A. Ittipiboon, Y. M. M. Antar, and D.Roscoe, Recent advances in dielectric resonator antenna technology, IEEE Antenna and Propagation Magazine, 40(3), 1998, 35-48. [5]Y. M. Pan, K. W. Leung, and K. Lu, Omnidirectional Linearly and Circularly Polarized Rectangular Dielectric Resonator Antennas, IEEE Trans. Antennas Propagation, 60(2), 2012, 751-759. [6]D. Guha, B.Gupta, C. Kumar, and M. M. Antar, Segmented Hemispherical DRA: New Geometry Characterized and Investigated in Multi-Element Composite Forms for Wideband Antenna Applications, IEEE Trans. Antennas Propagation, 60(3), 2012, 1605-1610. [7]D. Guha, Bidisha Gupta, and Y. M. M. Antar, Hybrid Monopole-DRAs using Hemispherical/ Conical-Shaped Dielectric Ring Resonators: Improved Ultra-Wideband Designs, IEEE Trans. Antennas Propaga. 60(1), 2012, 393 – 398. [8]A.Rashidian, K. Forooraghi, and M. Tayfeh-Aligodarz, Investigations on two-segment dielectric resonator antennas, Microwave and Optical Technology Letters, 45(6), 2005, 533– 537. [9]An Introduction to HFSS: Fundamental, Principles, Concepts, and Use Ansoft Corporation, 2010. [10]CST GmbH 2010 CST MICROWAVE STUDIO(r) User Manual V. 10, Darmstadt, Germany (www.cst.de). [11]S. A. Long and M.W. McAllister: Resonant Hemispherical Dielectric Antenna, IET Electronics Letters, 20(8), 1984, 657-659. [12]A. Petosa: Dielectric Resonator Antenna Handbook, (Artech House, Norwood, Massachusetts, USA; 2007). BIOGRAPHY Jitendra Kumar is currently working towards the Ph.D. degree in the Department of Electrical and Electronics Engineering, Birla Institute of Technology and Science, Pilani, (BITS-Pilani) Rajasthan, India. He received the Associate degree in Electronics & Telecommunication from The Institution of Electronics and Telecommunication Engineers (IETE), New Delhi, India, in 2004 and M.Tech. degree in Microwave Electronics from University of Delhi, South Campus, India, in 2008. His research interests are dielectric resonator antennas and design of microwave planner and passive components. International Conference on Communication Systems (ICCS-2013) B K Birla Institute of Engineering & Technology (BKBIET), Pilani, India October 18-20, 2013 Page 267
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  International Journal ofElectronics and Communication Engineering & Technology (IJECET), ISSN 0976 – 6464(Print), ISSN 0976 – 6472(Online), Special Issue (November, 2013), © IAEME Dr. Navneet Gupta obtained M.Sc. (Physics-Electronics) in 1995 from H.N.B Garhwal Central University (HNBGU), Srinagar, India with first rank in the University. He received M.Tech in Materials Technology in 1998 from Indian Institute of Technology (IIT-BHU) (formerly IT-BHU). He did his Ph.D. in the field of Semiconductor Devices in 2005 from HNBGU. Presently, he is Assistant Professor and Convenor-Departmental Research Committee in Electrical and Electronics Engineering Department, Birla Institute of Technology and Science, Pilani, (BITS-Pilani) Rajasthan, India. He has guided 1 Ph.D. student and is currently guiding 4 Ph.D. candidates. He is on doctoral advisory committee for 6 Ph.D. students. He completed 2 sponsored research projects from UGC and DST. His research interests include Semiconductor Device Modelling, RF-MEMS, Material Selection and Antenna Design. He is life member of several international and national professional bodies. He has over 50 research publications (of which 21 are in reputed peer reviewed international and national journals with good impact factors, and 29 in conference proceedings.). He has published six books in the areas of engineering physics and electronics engineering. He received the Bharat Jyoti Award in 2011 by IIFS, New Delhi, India, DST Young Scientist Award (Fast track Scheme) in Physical Sciences in 2007 and Gold Medal in M.Sc. His biography is included in Marquis Who's Who in World and Marquis Who's Who in Science and Engineering. He is expert reviewer of over 5 International Journals. He reviewed three books of Oxford University Press, Pearson Education and Tata McGraw Hill publishers. International Conference on Communication Systems (ICCS-2013) B K Birla Institute of Engineering & Technology (BKBIET), Pilani, India October 18-20, 2013 Page 268