JOURNAL OF APPLIED SCIENCES RESEARCH ISSN: 1819-544X Published BY AENSI Publication EISSN: 1816-157X http://www.aensiweb.com/jasr 2016 May; 12(5): pages 41-46 Open Access Journal Minkowski patch Microstrip Fractal Antenna for Multiband & Improved Bandwidth using Stacking Technique with Stripline Feeding 1 Sudhina H.K. and 2 Dr.Srivatsa S.K. 1 Associate Professor & Head, Dept.of E & CE., REC, Hulkoti, Gadag, India, Ph.D Scholar at St. Peter s University, Chennai. 2 Senior Professor, Dept of E & CE, Prathyusha Intitute of Technology & Management Tiruvallur, Chennai. India. Received 2 April 2016; Accepted 28 May 2016; Published 2 June 2016 Address For Correspondence: Sudhina H.K., Associate Professor & Head, Dept.of E & CE., REC, Hulkoti, Gadag, India,Ph.D Scholar at St. Peter s University, Chennai. E-mail: sudhinahk@gmail.com Copyright 2016 by authors and American-Eurasian Network for Scientific Information (AENSI Publication). This work is licensed under the Creative Commons Attribution International License (CC BY). http://creativecommons.org/licenses/by/4.0/ ABSTRACT This paper describes the design of minkowski microstrip fractal antenna up to third iteration is explained. FR4 substrate with thickness 1.6mm is used to design a Prototype antenna it s relative dielectric constant is of 4.4 using microstrip line feeding. The designed antennas are upgraded to operate under various specified bands around 2-3 GHz. IE3D simulator is used for the simulation and it is found that the simulated results are in good agreement with the experimental results. Stacking methods are also applied on the designed antenna using microstrip line feeding to increase the bandwidth. Comparison is done for with and without stacking method. KEYWORDS: Microstrip antennas, Minkowski, Multiband, Iterations, Stacking INTRODUCTION Antennas properties are applied in the modern radio communication systems [1]. Benoit Mandelbrot defined the meaning of antenna, which depict a family of complex shapes having an inherent self-similarity or self-affinity in their geometrical structure and for the study of nature patterns. For example, fractals have been lucratively used to model complex natural objects as galaxies, cloud boundaries, mounting ranges, coastlines, trees, leaves, snowflakes, ferns, and still more [2-5]. Also few more applications of antenna using fractal techniques are: fractal trees, Cantor linear array, Sierpinski gaskets and carpets, Minkowski curves Hilbert, Smale, and Koch etc. [3-7]. In many branches of science and engineering we have variety of applications for fractals, as antenna theory. In the field of fractal electrodynamics, the specialty of fractal antennas are its compact size, low profile, conformal, multiband and broadband properties, the fractal geometry is united with electromagnetic theory for the purpose of investigating a new class of radiation, propagation, and scattering problem [7]. The property of Multiband frequency is supported by Minkowski Fractal [8].The Minkowski curve can be characterized by the iteration factor [9]. The normal patch without any scraped out of copper indicates Zero iteration [10]. Similarly further iterations are formed by removing the four rectangular,12 rectangular & square shape of copper had been cut from the patch, as shown in Figure 1. To Cite This Article: Sudhina H.K. and Dr.Srivatsa S.K., Minkowski patch Microstrip Fractal Antenna for Multiband & Improved Bandwidth using Stacking Technique with Stripline Feeding, 2016. Journal of Applied Sciences Research. 12(5); Pages: 41-46
42 Sudhina H.K. and Dr.Srivatsa S.K., 2016/ Journal of Applied Sciences Research. 12(5) May 2016, Pages: 41-46 Fig. 1: Geometry of reference antenna 1 st iterated antenna, (c) 2 nd iterated antenna (d) 3 rd iterated antenna II Antenna Design: Design Calculation: The bigger and smaller size of square shape generator [11] is used for.minkowski fractal shape antenna design. Fig 2 and Table 1 show the modified Minkowski patch antenna dimensions. FR-4 board substrate with dielectric constant of 4.4 is used to design this antenna having, tangent loss of 0.025, and thickness of 1.6 mm, the feeding is a microstripline feeding Fig. 2: Dimensions of the proposed antenna Table 1: parameter and dimensions of proposed antenna Parameter Dimension (mm) W s 54 L s 54 W p 28.86 L p 28.86 W f 4 L f 9.95 Minkowski mistrostrip fractal antennas for microstrip line feeding without stacking: The structure of prototype minkowski mistrostrip fractal antennas is shown in Figure 1,for microstrip line feeding for without stacking Fig1 is the reference antenna, fig 1 to figure 1(d) shows first, second and third d iterated antennas respectively. fabricated antennas are shown in figure 3., a rectangular stripline feed is given to control the location of the resonant frequency of the different modified Minkowski microstrip fractal antennas Fig. 3: Fabricated view of base antenna, 1 st, 2 nd and 3 rd iterated antennas Minkowski mistrostrip fractal antennas for microstrip line feeding with stacking: The stacking method is employed on minkowski microstrip fractal antenna to the ref, 1 st, 2 nd and 3 rd iterations. Figure 4 represents a fabricated view of the stacked minkowski mistrostrip fractal antennas for microstrip line feed.
43 Sudhina H.K. and Dr.Srivatsa S.K., 2016/ Journal of Applied Sciences Research. 12(5) May 2016, Pages: 41-46 Fig. 4: Fabricated view of stacked Minkowski mistrostrip fractal antennas. RESULTS AND DISCUSSION Minkowski microstrip fractal antennas were studied for without and with stacking using IE3D simulation tool. The parameters like return loss and bandwidth were evaluated using well known simulator, and it was verified using vector network analyzer. Both the Simulated results and experimental analysis were found to be in a good agreement.. Figure 5, figure 7, figure 9 and figure 11 represents the results of simulated return loss characteristics and figure 6, figure 8, figure 10 and figure 12 demonstrates the corresponding practical return loss characteristics recorded from vector network analyzer for both without stack and with stacked structures of minkowski mistrostrip fractal antennas with microstrip line feeding. Table 2 shows the various evaluated values of the performance parameters like the variation of bandwidth, resonant frequency, return loss and gain with reference to without and with stacking of Minkowski microstrip fractal antenna. The best possible resonant frequency is operating around 2.47 GHz, for the various iterations were statistically evaluated and those are summarized in the table 2. Fig. 5: Simulated return loss characteristics of without and with stacking implemented on Minkowski fractal antenna for reference antenna Fig. 6: Practical return loss characteristics of without and with stacking implemented on Minkowski fractal antenna for the reference antenna Fig. 7: Simulated return loss characteristics of without and with stacking implemented on Minkowski fractal antenna for 1 st iteration antenna
44 Sudhina H.K. and Dr.Srivatsa S.K., 2016/ Journal of Applied Sciences Research. 12(5) May 2016, Pages: 41-46 Fig. 8: Practical return loss characteristics of without and with stacking implemented on Minkowski fractal antenna for the 1 st iteration antenna. Fig. 9: Simulated return loss characteristics of without and with stacking implemented on Minkowski fractal antenna for 2 nd iteration antenna. For without stacking, the reference antenna implies a resonant frequency of -20 db at 2.3 GHz for without stacking and a bandwidth of 56 MHz and in the experimental analysis value observed for resonant frequency at - 12.31 db with a bandwidth of 20 MHz. With stacking, the simulated values for the reference antenna shows the resonant frequency of -22db with increased bandwidth of 96 MHz and experimental analysis shows -14.31db with an increase of bandwidth to 40 MHz, compared with reference without stacking. Fig. 10: Practical return loss characteristics of without and with stacking implemented on Minkowski fractal antenna for the 2 nd iteration antenna. Fig. 11: Simulated return loss characteristics of without and with stacking implemented on Minkowski fractal antenna for 3 rd iteration antenna
45 Sudhina H.K. and Dr.Srivatsa S.K., 2016/ Journal of Applied Sciences Research. 12(5) May 2016, Pages: 41-46 Fig. 12: Practical return loss characteristics of without and with stacking implemented on Minkowski fractal antenna for the 3 rd iteration antenna After first iteration, the resonant frequency shifts to left in significant as summarized in Table 2. Results of designed antennas with various resonant frequencies whose characteristic features like return loss and its band width are noted. Experimental results are close in agreement with the simulated results using IE3D software. There is a shift in resonating frequency with the increase of the iterations for both cases, without and with stacking. Table 2: Result of simulated and experimental for stacked and without stacked. Resonant frequency (GHz) Return loss(db) Gain (db i) Bandwidth (MHz) Iterations for stripline feeding Simulated Experiment Simulated Experiment Simulated Simulated Experi GHz ment Reference iteration antenna Without stack 2.3 2.47-20 -12.34 3.0 56 20 With stack 2.39 2.47-22 -14.31 0.5 152 60 1 st iteration Antenna Without stack 2.4 2.47-21 -13.02 4.0 175 100 With stack 2.42 2.47-24 -16.30 4.0 180 `120 2 nd iteration Antenna Without stack 2.45 2.47-23 -11.7 3.0 210 40 With stack 2.46 2.47-23.5-13.1 4.1 340 60 3 rd iteration Antenna Without stack 2.21 2.47-14.5-19 4.2 240 350 With stack 2.25 2.47-18 -26.6 5.2 300 400 Conclusion: This paper describes a design of Minkowski microstrip fractal antenna with a stripline feed for without and with stacking, which can be used for various frequency bands. A comparison is carried out with reference to without and with stacking. The optimized bandwidths observed after third iteration with an enhanced bandwidth of 148 MHz for simulated and 340 MHz for practical. REFERENCES 1. Fujimoto, K., J.R. James, 2001. Mobile Antenna Systems Handbook. Artech House, Boston-London. 2. Mandelbrot, B.B., 1996. The Fractal Geometry of Nature, N.Y. W. H. Freeman. 3. Peitgen, H.O., P.H. Rixter, 1998. The Beauty of Fractals, Images of Complex Dynamic Systems, Springer-Verlag, Berlin-N.Y. 4. Peitgen, H.O., H. Jurgens, D. Saupe, 2010. Chaos and Fractals, New frontiers in science, Springer- Verlag, New-York. 5. Werner, D.H., R.L. Haupt, P.L. Werner, 1999. Fractal Antenna Engineering: The Theory and Design of Fractal Antenna Arrays, IEEE Antennas and Propagation Magazine, 41(5): 37-59. 6. Werner, D.H., S. Ganguly, 2003. An Overview of Fractal Antenna Engineering Research, IEEE Antennas and Propagation Mag., 45(1): 38-57. 7. Puente-Baliarda, C., R. Pous, 2005. Fractal Design of Multiband and Low Side-Lobe Arrays, IEEE Antennas and Propagation, 44(5): 730-739. 8. Paulo, G.H., F. Silva, J.I.A. Trindade, A.G. d'assucao, 2010. Experimental Characterization of Reconfigurable Multiband Minkowski Patch Antenna, International Workshop on Antenna Technology (iwat): 1-4.
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