International Journal of Engineering Research & Technology (IJERT) ISSN: 2278-0181 Vol. 3 Issue 4, April - 2014 Analysis of Koch Snowflake Fractal Antenna for Multiband Application
Solanki Neha A. Piyush C. Dalsania Hiren J. Kathiriya Student, Dept. of ECE Lecturer, Dept. of ECE Asst. Prof., Dept. of ECE R. K University Dr. J. N. Mehta Govt. Polytechnic R. K University Rajkot, India Amreli, India Rajkot, India
Abstract— This paper discusses the Koch snowflake behavior of the fractal antenna. The antenna has been designed for increasing outer perimeter of triangular shape patch by using self-similarity property and analyzed performance on multiband .There are number of example of self-similarity and space filling property of fractal antenna. We are examining number of iteration by the designing Koch snowflake for different resonant frequency.
Keywords— fractal antenn; iterative method; multi band;
I. INTRODUCTION The Koch snowflake it became an important sample of fractal set. The objective of this paper is to be design and, simulate Koch snowflake fractal antenna. The behavior and properties of an antenna are investigated. Multiband operation is becoming increasingly popular in several practical applications including next-generation wireless terminals. Fractals antennas that are small in size and simple in structure are typically demanded for such applications IJERT[1].IJERT Fractals antennas are widely preferred for wireless communication systems as they are of small size, light weight, low profile, low cost, and are easy to fabricate and assemble [2]. The Koch snowflake geometry drew the attention of researchers as it is smaller than other patch geometries [3].
II. GEOMETRY OF KOCH SNOWFLAKE
A. Koch Snowflake Fractal investigated in this study is based on a Koch snowflake. Comparisons can be drawn here between the Periodic Patterned designs highlighted in fig. (1), it was known as a Koch snowflake fractal. It originates from a plain square patch and subsequent iterations produce a cross-like fractal patch with ever more fine details at its edges such a design has several parameters which can be varied such as the depth and size of the removed segments [3]. Fig. 2. Design Steps construction of a Koch snowflake fractal
B. Self-Similarity Design As shown in Fig. (2) Increasing outer perimeter of triangular patch according to the fractal formula of regular self-similarity pattern.
Fig. 1. Basic Steps construction of a Koch snowflake fractal
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III. ANTENNA DESIGN Ansoft Corporation koch_1 HFSSDesign1 Name X Y Curve Info m1 7.1706 -15.7420 dB(S(WavePort1,WavePort1)) Many variation are possible with square size of patch -2.00 m2 8.3110 -18.6584 Setup1 : Sw eep1 m3 9.2676 -10.6818 antenna dimension A’s value changes as well as fractal steps -4.00 m4 9.7090 -13.2439 m5 11.1806 -16.0857 iteration factor [3]. Here we take 1/3 iteration factor with -6.00 m6 12.4682 -15.9546 m7 14.0502 -17.7740
dimension A= 9cm. Here we describe up to 4 iteration step -8.00 are Koch fractal geometry [4]. -10.00 m3
The length of the boundary of S (n) at the nth iteration of -12.00 m4 dB(S(WavePort1,WavePort1)) the construction is 3*(4/3) ^n*s, where s denotes the length of -14.00
m1 each side of the original equilateral triangle [5]. Therefore the -16.00 m5 Koch snowflake has a perimeter of infinite length -18.00 m2
7.00 8.00 9.00 10.00 11.00 12.00 The area of S (n) is Freq [GHz] 3s21n 3 4k Fig. 4. Iteration -1 of Koch snowflake Fractal Antenna’s Return Loss 1 k 49k1 B. Simulation Result For Iteration 2 Letting n go to infinity shows that the area of the Koch
2 snowflake is 23s . 5
Substrates Material R. T. duroid epoxy having permittivity (εr) of 4 Dimension: 110*100*1.5 mm Patch Design shapes changes according to fractal variation A=9 cm Feeding: Commercial coaxial dimension used and feeding position center of the patch.
IV. EXPERIMENTAL RESULT AND SIMULATION
A. Simulation Result For Iteration 1 Simulation result of individual iteration step by step with S11 (Return loss in dB), VSWR radiation pattern and reading tables Fig. 5. Iteration -2 of Koch snowflake Fractal Antenna The structure of Koch snowflake fractal antenna with firstIJERTIJERT iteration is as follows and on simulating the above structure with the help of Ansoft HFSS, the following results were AnsoftName CorporationX Y koch_2 HFSSDesign1 obtained. m1 7.0970 -25.1880 Curve Info m2 8.4582 -12.1860 dB(S(WavePort1,WavePort1)) m3 9.8194 -13.9347 Setup1 : Sw eep1 m4 11.5853 -14.2963 -5.00
-10.00
m2
m3 m4 -15.00
-20.00 dB(S(WavePort1,WavePort1))
-25.00 m1
7.00 8.00 9.00 10.00 11.00 12.00 Freq [GHz]
Fig. 6. Iteration -2 of Koch snowflake Fractal Antenna’s Return Loss
Fig. 3. Iteration -1 of Koch snowflake Fractal Antenna
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C. Simulation Result For Iteration 3 TABLE I. Antenna Parameters Return Iteration Resonant freq. Peak Peak VSWR Loss (GHz) gain Directivity (dB) 7.17 1.4 -15 5.17 4.29
1st 8.31 1.26 -18 5.97 5.54
11.18 1.3 -16 1.05 4.69
7.09 1.11 -25 17.65 6.85
8.45 1.65 -12 0.80 4.79 2nd 9.8 1.5 -13 1.59 8.05
11.58 1.47 -14 4.39 14.86
6.80 1.14 -23 12.63 6.38 8.23 1.17 -22 2.96 6.94 Fig. 7. Iteration -3 of Koch snowflake Fractal Antenna 3rd 9.12 1.04 -32 6.91 16.8
10.33 1.17 -21 2 8.73 AnsoftName CorporationX Y koch_3 HFSSDesign1 m1 6.8027 -23.5206 Curve Info m2 8.2375 -22.0532 dB(S(WavePort1,WavePort1)) 10.88 1.11 -25 1.60 5.95 m3 9.1204 -32.3374 Setup1 : Sw eep1 m4-5.00 10.3344 -21.8006 m5 10.8863 -25.4495 -10.00 V. CONCLUSION -15.00 The resonant frequency increases with increase in the
-20.00 number of iterations. The multiband behavior is obtained as m2 m4 m1 the numbers of iterations are increased .The return losses dB(S(WavePort1,WavePort1)) -25.00 m5 improve as the number of iterations increase. The bandwidth
-30.00 of the antenna gets increased too with increase in the number m3 of iterations. Improvement in VSWR is also observed with
6.00 7.00 8.00 9.00 10.00 11.00 increase in iterations. The fractal geometry effect on patch Freq [GHz] antenna has been analyzed. This Koch snowflake antenna is a Fig. 8. Iteration -3 of Koch snowflake Fractal Antenna’s Return LossIJERT IJERTgood example of the properties of fractal incremental boundary patch antennas. As the fractal iteration increases, perimeter of patch increases and effective area of antenna increases with improve multiband application. . The radiator is now resonant at more frequencies. It gives multiband properties to fractal geometry antenna with directive patterns. This behavior is obtained with a coaxial feeding scheme. So, fractal boundary patch antennas are an interesting replacement in the multiband antenna with broadside radiation patterns and with efficient directivity. This geometry offers numerous variations in dimension and design, hence gives wide scope for commercial applications. REFERENCES [1] Mandelbrot B.B., “The Fractal Geometry of Nature”, W. H. Freeman, New York, 1983 [2] R Garg, P. Bhartia, I. Bahl, and A. Ittipiboon, Microstrip Antenna Design Handbook, Artech House, Norwood, MA, 2001. [3] K.J. Vinoy, Jose K. Abraham, and V.K. Varadan, Fractal Dimension Fig. 9. E-Field Distribution of Koch snowflake Fractal Antenna and Frequency Response of Fractal Shaped Antennas, 2003 IEEE [4] Puente C., Romeu J., Pous R., Cardana A., “On the behavior of the Simulation results of various iteration steps shown on Sierpinski multiband antenna”, IEEE Trans. on Antennas and above figures. Incremental properies of koch snowflake Propagation, Vol. 46, pp. 517- 524, 1998 gives increasing in resonanant frequency observed result [5] Lee. Y., Yeo. J., Mittra R., Ganguly S. and Tenbarge J., “Fractal and Multiband Communication Antennas”, IEEE Conf. on Wireless shown in table 1. Communication Technology, pp. 273-274, 2003.
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