JOURNAL OF TELECOMMUNICATIONS, VOLUME 7, ISSUE 2, MARCH 2011 46

Design of Modified Sierpinski Carpet Fractal Antenna 1

2

3

Rajneesh Chawhan , Dr. P. K. Singhal and Dr. C. Das. Gupta

Abstract-- This paper describes the design and fabrication of modified Sierpinski carpet fractal antenna. The analysis took place between ranges of 0.5GHz to 3GHz. The fabricated modified Sierpinski carpet fractal antenna proves that it is capaple to create multiband frequencies. There are five resonant frequencies appeared at 0.89 GHz, 1.91 GHz, 2.17 GHz, 2.72 GHz and 3.0 GHz.

Index Terms-- microstrip antenna, fractal.

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I. INTRODUCTION

I

N modern wireless communication systems and increasing of other wireless applications, wider bandwidth and low profile antennas are in great demand for both commercial and military applications. This has initiated antenna research in various directions, one of them is using fractal shaped antenna elements. Traditionally, each antenna operates at a single or dual frequency bands, where different antenna is needed for different applications. This cause a limited space and place problem. In order to overcome this problem, multiband antenna can be used, where a single antenna can operate at many frequency bands. One technique to construct a multiband antenna is by applying fractal shape into antenna geometry. The behaviors of this antenna are investigate such as return loss, number of iteration, simulation, fabrication and testing have been done. The entire fractal antennas shows multiband in resonant frequencies.

Stage 0

Stage 1

II. ANTENNA CONFIGURATION The antenna was feed with transmission line feeding technique. The iteration process is done up to second iteration. The design is fabricated using glass-epoxy material with relative permittivity,

εr

= 4.4, substrate

thickness, d = 1.6mm where the radiating element is the cooper clad. The iteration of the antenna from zero stage to until second stage is shown below:

Stage 2 Fig.1 The stages iteration of modified Sierpinski Carpet Fractal antenna The design of the antenna was start with single element using basic square patch microstrip antenna. The operating frequency is at 1.0GHz. Length, L and width, W can be calculated by using equation (1), (2), (3), and (4).

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• PhD student (Design & Analysis of Fractal Antenna’s). • Prof. & Head, ECED Madhav Institute of Tech. & Science, Gwalior. • Senior Member IEEE, Pensioner Professor IIT, Kanpur. © 2011 JOT http://sites.google.com/site/journaloftelecommunications/

JOURNAL OF TELECOMMUNICATIONS, VOLUME 7, ISSUE 2, MARCH 2011 47

Width,

vo 2 fr

W=

III. RESULT AND DISSCUSSION

2 εr +1

(1) Solid line-Simulated , Dotted line-Measured

Effective dielectric,

2

+

ε r +1 2

1   1 + 12d /W

  

(2)

Fringing field,

(ε eff + 0.3) W + 0.262  d  ∆l = 0.412d W   ε eff − 0.258  + 0.813  d 

(

-10 -15 -20 -25 -30

(3)

0.5

1

)

1.5

2

2.5

Frequency(GHz)

Fig. 2 Variation of return loss with frequency for base shape.

Length,

v0

L=

-5 ReturnLoss(dB)

εr +1

ε eff =

0

2 f r ε eff

− 2∆l

(4)

Where

Table 1 Frequencies at which minimum return loss occur for base shape.

Frequency (Simulated)

1.0 GHz

2.0 GHz

v0

= Velocity of light in free space. -12.46 dB

= Operating resonant frequency.

Return loss (Simulated)

-26.78 dB

fr

εr

= Dielectric constant of the substrate used.

Frequency (Measured)

0.99 GHz

1.986 GHz

ε eff

= effective dielectric constant.

-19.1 dB

-10.6 Db

d

= height of the substrate.

Return Loss (Measured)

The generalized formulas for iteration n are as follows: Nn = The number of black box. Ln = The ratio for length. An = The ratio for the fractal area after the nth iteration. n

= The iteration stage number.

Nn = 8 n

1  3

n

Ln =  

8  An =   9 

(5) (a)

n

(6)

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JOURNAL OF TELECOMMUNICATIONS, VOLUME 7, ISSUE 2, MARCH 2011 48

Table 2 Frequencies at which minimum return loss occur for first iteration Frequency (Simulated)

0.9GHz

1.95GHz

2.21GHz

ReturnLoss

-14.05dB

-14.3dB

-19.43dB

Frequency (Measured)

0.876GHz

1.90GHz

2.14GHz

ReturnLoss

-10.5dB

-15.6dB

-21.8dB

(Simulated)

(Measured) ( b)

Fig. 3

Radiation pattern at f =1GHz (a) (b)

E-total, phi = 0(deg) E-total, phi = 90(deg

In Fig.2: the return loss -26.78 dB and -12.46 GHz with frequency 1.0GHz and 2.0 GHz respectively was obtained from simulation. The measurement response frequency has shifted to 0.99 GHz and 1.986 GHz with measured return loss -19.1 dB and -10.6 dB respectively. (a)

Solid line-Simulated , Dotted line-Measured

ReturnLoss(dB)

0 -5 -10 -15 -20 -25 0.5

1

1.5

2

2.5

3

Frequency(GHz)

Fig. 4 Variation of return loss with frequency for first iteration.

(b) Fig. 5 Radiation pattern at f =0.9GHz (a)

E-total, phi = 0(deg)

(b)

E-total, phi = 90(deg)

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JOURNAL OF TELECOMMUNICATIONS, VOLUME 7, ISSUE 2, MARCH 2011 49

(b) Fig. 7

Radiation pattern at f =2.21GHz

(a) (a)

E-total, phi = 0(deg)

(b)

E-total, phi = 90(deg)

Fig. 4 shows the result of return loss for first iteration. The resonant frequency was found at 0.9GHz, 1.95GHz and 2.21GHz from simulation. Measurement response frequencies have shifted at 0.876GHz, 1.90GHz, and 2.14GHz. The best return loss -19.43dB (2.21GHz) was found from simulation. Meanwhile, return loss -21.8dB (2.21GHz) was found from measurement.

Solid line-Simulated , Dotted line-Measured

(b) Radiation pattern at f =1.95GHz (a)

E-total, phi = 0(deg)

(b) E-total, phi = 90(deg)

ReturnLoss(dB)

Fig. 6

0 -5 -10 -15 -20 -25 0.5

1

1.5

2

2.5

Frequency(GHz)

Fig. 8 Variation of return loss with frequency for second iteration.

(a)

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JOURNAL OF TELECOMMUNICATIONS, VOLUME 7, ISSUE 2, MARCH 2011 50

Table 3 Frequencies at which minimum return loss occur for second iteration Frequency (Simulated)

0.89

1.91

2.17

2.72

GHz

GHz

GHz

GHz

3.0 GHz

ReturnLoss

-12.6

-12.5

-19.1

-13.0

-18.25

(Simulated)

dB

dB

dB

Db

dB

Frequency (Measured)

0.87

1.88

2.13

2.7

2.95

GHz

GHz

GHz

GHz

GHz

-10.7

-16.3

-20.1

-19.1

-11.0

dB

dB

dB

dB

dB

ReturnLoss (Measured)

(a)

(b) Fig. 10

(a)

Radiation pattern at f =1.91GHz (a)

E-total, phi = 0(deg)

(b) E-total, phi = 90(deg)

(b)

Fig. 9

Radiation pattern at f =0.89GHz (a)

E-total, phi = 0(deg)

(b)

E-total, phi = 90(deg) © 2011 JOT http://sites.google.com/site/journaloftelecommunications/

(a)

JOURNAL OF TELECOMMUNICATIONS, VOLUME 7, ISSUE 2, MARCH 2011 51

(b)

Fig. 11

(a)

Radiation pattern at f =2.17GHz (a)

E-total, phi = 0(deg)

(b) E-total, phi = 90(deg)

(b)

Fig. 13

(a)

Radiation pattern at f =3GHz (a)

E-total, phi = 0(deg)

(b)

E-total, phi = 90(deg)

Second iteration Fig. 7 shows that five frequencies responses existed at 0.89GHz, 1.91GHz, 2.17GHz, 2.72GHz and 3.0GHz for simulation. There were all frequencies response obtained from measurement. The best return loss at 2.17GHz(-19.1dB) for simulation. While, -20.1dB (2.13GHz) was the best return loss for measurement. As the Fig. 12 illustrated, there were a side lobes existed at higher frequency. The side lobes occur at 2.72GHz.

(b) Fig. 12

Radiation pattern at f =2.72GHz (a)

E-total, phi = 0(deg)

(b)

E-total, phi = 90(deg) © 2011 JOT http://sites.google.com/site/journaloftelecommunications/

JOURNAL OF TELECOMMUNICATIONS, VOLUME 7, ISSUE 2, MARCH 2011 52

IV CONCLUSION The antenna has been design, simulated and fabricated. The multiband frequencies appeared after applied fractal technique. It is observed that as the number of iterations are increased, number of frequency bands also increases. For zero iteration two bands occur, for first iteration three bands occur and for second iteration five bands occur. The antenna can be used for GPS, WLAN applications.

V REFERENCES [1]

Constantine A. Balanis, “Antenna Theory”, Second Edition, John Wiley & Son , 2007

[2]

Abd M.F; Ja’afar A.S.: & Abd Aziz M.Z.A;” Sierpinski Carpet Fractal Antenna”, Proceedings of the 2007 Asia-Pacific conference on applied electromagnetics, Melaka, December 2007.

[3]

David M.Pozar, “Microstrip Antenna”, IEEE Transaction on Antenna and Propagation, January1992.

[4]

M.K. A. Rahim, N. Abdullah, and M.Z. A. Abdul Aziz, “Micro Strip Sierpinski Carpet Antenna Design” IEEE Transaction on Antenna and propagation,December 2005.

[5]

M.K. A.Rahim, N. Abdullah, and M.Z. A. Abdul Aziz, “Micro Strip Sierpinski Carpet Antenna using Transmission line Feeding”, IEEE Transaction on Antenna And Propagation, December 2005.

Rajneesh Chauhan, B.E. (Electronics) in 1997. M.Tech.(Digital Communication) in 2010 from U.P.T.U. & presently working in Meerut Institute of Engineering & Technology, Meerut (India) affiliated by UPTU, Lucknow. Presently working as a Assistant Professor Since 2003. and written one book on Switching Theory with ISBN 81-88476-29-X published by JPNP’s, Meerut Prof. (Dr.) P.K. Singhal presently working as a Professor & Head in Department of Electronics Madhav Institute of Technology & Science, Gwalior and published lmore than hundred research paper, which include papers in IEEE transaction, International & National Journals, International and National Conference. Prof.(Dr.) Chinmoy Das Gupta B.Tech. (Electronics & Telecommunication) in 1961 from Jadavpur University, M.Tech. in Electro Vaccum Devices in 1963 from IIT Bombay and Ph.D. from Leningard Institute of Electrical Engg. U.S.S.R. (at present St’ Peterburg Electro technical University) in 1970. He is a Senior Member IEEE, USA & Fellow Institute of Engineers (Life), Pensioner Professor IIT, Kanpur.

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