A NEW DESIGN FRACTAL ANTENNA FOR WIRELESS COMMUNICATION

Pradeep Kumar1, Bhawna Sardana 2

Assistant professor1, M.Tech VLSI student2

1Department of Electronics & Communication Engineering, DITMR Faridabad,2A.F.S.E.T. Dhauj, Faridabad

Email: pkuk2011@gmail.com, Bhawna.sardana19@gmail.com

Abstract: A fractal is a recursively generated object having a fractional dimension. Many objects, including antennas, can be designed using the recursive nature of a fractal. This paper describes the use of fractal for different wireless applications operating at frequencies 2- 2.5 Ghz .the size of antenna is reduced in each iteration without affecting the frequency of operation and bandwidth 5.5%.the area of this antenna is 50% to 60% smaller than those of conventional patch antenna.Keywords: Fractal Antenna, bandwidth, wlan, patch antenna.

1. INTRODUCTIONThere has been an ever-growing demand in both the military as well as commercial sector for antenna design that processes the following highly desirable attributes:1. Compact size2. Low profile3. Conformal4. Multiband or BroadbandThere are a variety of approaches that have been developed over the years, which can be utilized to achieve one or more of these design objectives. For instance an excellent overview of various useful techniques for designing compact (i.e. miniature) antennas may be found in [1] and [2].moreover a number of approaches for designing multi-band (primarily, dual band) antennas have been summarized in [3].Recently the possibility of developing antenna designs that exploit in some way the properties of fractals to achieve these goals, at least in part, has attracted a lot of attention. The term fractal, which means broken or irregular fragments, was originally coined by Mandelbrot [4] to describe

a family of complex shapes that possess an inherent self- similarity or self- affinity in their geometrical structures. The original inspiration for the development of fractal geometry came largely from an in -depth study of the patterns of nature. For instance, fractals have been successfully used to model such complex natural objects as galaxies, cloud boundaries, mountain ranges, snowflakes trees, leaves, ferns and much more. Since the pioneering work of Mandelbrot and others, a wide variety of applications for fractal continue to be found in many branches of science and engineering .one such area is fractal electrodynamics [5-11],in which fractal geometry is combined with electromagnetic theory for the purpose of investigating a new class of radiation ,propagation, and scattering problems. One of the most promising areas of fractal-electrodynamics research is in application to antenna theory and design.

Traditional approaches to the analysis and design of antenna systems have their foundation in Euclidean geometry .There has been a considerably amount of recent interest, however in the possibility of developing new types of antenna that employ fractal rather than Euclidean geometric concepts in their design. We refer to this new and rapidly growing field of research as Fractal Antenna Engineering. Because fractal geometry is an extension of classical geometry, its recent introduction provides engineers with the unprecedented opportunity to explore a virtually limitless number of previously unavailable configurations for possible use in the development of new and innovative antenna designs. There are primarily two active areas of research in fractal antenna

engineering. These include: 1.) The study of fractal –shaped antenna elements, and 2.) the use of fractal in the design of antenna arrays. The purpose of this article is to provide an overview of recent developments in the theory and design of fractal antenna elements, as well as fractal antenna arrays. The related area of fractal frequency-selective surfaces will also be considered in this article.

We note that there are a number of patents on fractal antenna designs that have been filed and awarded in recent years. The purpose of this article , however , is to present an overview of letters and papers published in technical journals that deal with the subject of fractal antenna engineering. Therefore, the contents of specific patents will not be discussed here. The interested reader is encouraged to search the various patent databases for this information.

Antenna Design

The conventional edge-fed microstrip rectangular patch antenna is designed by following the standard procedures. The parameters taken into account for the design are the resonant frequency (fr = 2.45GHz), dielectric constant (Hr= 1.5) and thickness of the Substrate (h = 1mm). The conventional patch antenna is shown in design 1

Design 1

Figure 1 design of patch antenna in HFSS

The size of the design antenna is given in the below table with the coordinates taken into design geomatry in HFSS .

dx,dy,dz

X Y Z Material

geometry

Ground

0,0,0 36

47

0.02

Pec box

Substr 0,0,0.0 3 4 1.5 Fr4 box

ate 2 6 7 epoxy

Patch 5,5,1.5 27

38

0.02

Pec box

Microstrip

32,14,1.52

4 2.5

.02 Pec box

Lumped port

36,14,0.02

X 2.5

1.52

rectangle

Air box

-3,-3,-3 40

50

6 Vaccum

box

Table: 1 design geometry of design 1 in HFSS

The designed patch is showing resonance at frequency 2.45 as shown in the return loss of the designed microstrip patch antenna..

Figure 2: the return loss vs frequency plot of design 1

The return loss calculated from graph is -38 db which shows it has good reflection at 2.45 GHz

The radiation pattern of antenna is shown below for theta =0 degree

Figure 3: ratiation pattern of design 1

The radiation pattern of antenna is shown below for theta =90 degree

Figure 4: ratiation pattern of design 1

The design 2 shown below is similar to above design 1 but a portion of the patch antenna is cut off to introduce the fractial effect such that the effective area of patch antenna get reduced with small effect on its frequency.

Design 2

Figure 5:design2 of patch antenna in HFSS

The portion cut from the patch is of size have the following dimensions shown in the table.

Table: 2 design geometry of design 2 in HFSS

The resulting antenna is showing resonance at frequency 2 GHz as shown in the return loss of the designed microstrip patch antenna. The return loss calculated from graph is -32 db which shows it has good reflection at 2 GHz.

Figure 6: the return loss vs frequency plot of design 2

The radiation pattern of new designed antenna is shown below for theta =0 degree

Figure 7: ratiation pattern of design 2

The radiation pattern of new designed antenna is shown below for theta =90 degree

Figure 8: ratiation pattern of design 2

In the similar way the identical rectangular patches are cut off from the patch keeping design 2 in it and repeating the fractal effect in it

.The design 3 is have very less area as compare to design 2 keeping the radiation property same and with reduced patch area.

Design 3

Figure 9: design 3 of fractial antenna in HFSS

The dimensions of the design 3 is shown in below table .

Iteration box 1

12 ,16 ,1.52

10 16 0.02 Pec

Box2 7 ,6 ,1.52

4 4 0.02 Pec

Box3 16 ,6 ,1.52

4 4 0.02 Pec

Box4 6 ,16 ,1.52

4 4 0.02 Pec

Box5 6 ,26 ,1.52

4 4 0.02 Pec

Box6 6 ,34 ,1.52

4 4 0.02 Pec

Box7 14 ,3 4 4 0.02 Pec

5 ,1.52

Box8 22 ,35 ,1.52

4 4 0.02 Pec

Box9 25 ,27 ,1.52

4 4 0.02 Pec

Table : 3 design geometry of design 3 in HFSS

The design 3 antenna is showing resonance at frequency 2 GHz as shown in the return loss of the designed microstrip patch antenna. The return loss calculated from graph is -32 db which shows it has good reflection at 2 GHz.

Figure 10: The return loss vs frequency plot of design 3

The radiation pattern o design 3 antenna is shown below for theta =0 degree

Figure 11: ratiation pattern of design 3

The radiation pattern o design 3 antenna is shown below for theta =90 degree

Figure 12: ratiation pattern of design 3

Conclusion :The paper presents the reduction in size keeping resonance at same frequency with the help of fractial geomotry introduced in the patch.the design process is carried out in

High Frequency Simulating Software.the designed antenas can be used for wireless aplllications in range of 2 ghz and 2.45 ghz.This paper is very helpful for the beginners start working in HFSS.

REFERENCES

[1] M. F. Bamsley, Fractals Everywhere, 2nd ed., New York: Academic Press Professional, 1993.

[2] P. S. Addison, Fractals and Chaos: An Illustrated Course, Bristol, U.K.: Institute of Physics Publishing, 1997.

[3] B. B. Mandlebrot, The Fractal Geometry of Nature, New York: W.H. Freeman, 1983.

[4] C. Puente-Baliarda, J. Romeu, R. Pous, and A. Cardama, “On the Behaviour of the Sierpinski Multiband Fractal Antenna,” IEEE Transaction on Antennas and Propagation, 46, No. 4, pp. 517-524, 1998.

[5] Y. Kim and D.L. Jaggard, “The Fractal Random Array,” Proceedings of the IEEE, 74, No. 9 , pp 1278 – 1280, 1986.

[6] H. E. Dimas, D. L. Jaggard, and A.D. Jaggard, “Spiral Fractal Arrays,” University of Pennsylvania, NSF/ SUNFEST Summer Undergraduate Research, 2000.

[7] V.F. Kravchenko and V.M. Masyuk, “Peculiarities of the Design of Spiral Fractal Antenna Arrays,” Fifth International Kharkov Symposium on Physics and Engineering of Microwaves, Millimeter, and Submillimeter Waves, 2, pp. 952 - 954, 2004.

[8] A. Karmakar, R. Ghatak, R.K. Mishra, and D.R. Poddar, “A Sierpinski Carpet Fractal Based Design of Thinned Rectangular Microstrip Antenna Array,” Applied Electromagnetics Conference, pp 1 – 3, 2009.

[9] D.H. Werner, R.L. Haupt, and P.L. Werner, “Fractal

Pradeep Kumar received his B.tech. degree in Electronics and Communication Engineering from Kurukshetra University in 2008, M.tech degree in Electronics and Communication from Kurukshetra University in 2011.He has 1 year of teaching experience in very reputed University Engineering Colleges of Kurukshetra University. His research interest includes Microstrip Patch Antenna, CAD of antennas. He has published 1 research papers in International Journal of applied Engineering research .

Bhawna Sardana received his B.tech. degree in Electronics and Communication Engineering from Maharshi Dayanand University, Rohtak in 2010,She is pursuing M.tech from Al-Falah School of Engineering and Technology,Faridabad in VLSI specialisation.