IJECT Vo l . 5, I spl - 2, Jan - M 2014 Antenna ...

[Pages:3]ISSN : 2230-7109 (Online) | ISSN : 2230-9543 (Print)

IJECT Vol. 5, Issue Spl - 2, Jan - March 2014

Antenna Miniaturization Using Giuseppe

Peano Fractal Structure

1Tanmoy Sarkara, 2Joydeep Chakravortya, 3Rowdra Ghatakb

1,2Radionics laboratory, Dept. of Physics, The University of Burdwan, Burdwan, India 3Microwave and Antenna Research laboratory, Dept. of ECE, National Institute of Technology

Durgapur, West Bengal, India

Abstract The present paper focuses on the miniaturization technique of antennas using Giuseppe Peano (GP) Fractal structure. At first, we have proposed a modified E-shape multiband patch antenna with enhanced multiband characteristics using Giuseppe Peano fractal structure. Then the miniaturization of a simple patch antenna using Giuseppe Peano (GP) structure at the edges has been considered. In both of the cases, it has been observed that the deviations in antenna parameters are within the tolerable range.

Keywords Patch Antenna , Multiband , Fractal Antenna

I. Introduction Fractals are geometrical shapes which are self-similar, repeating themselves at different shapes. Benoit Mandelbrot, a French mathematician, first introduced the concept of the fractal in 1951 [2] .Since then, various branches of science and technology is using this concept for applications. In 1890, Giuseppe Peano introduced a new fractal function for space filling property of a structure known as Giuseppe Peano. This concept of GP fractal structure has been introduced in antenna engineering for miniaturization purpose [3-4]. The aim of this paper is to observe the advantage of GP Fractal structure in antenna miniaturization. Space filling properties of a fractal antenna can make it smaller in size, reduction in radar cross section as well as reduction in mutual coupling in antenna array [5]. The dimension of an antenna is a function of its operating wavelength and if the total length is less than quarter wavelength, it become inefficient radiator as its radiation resistance decreases and the reactive energy in the near field region increases. These lead to decrease in the antenna gain. Fractal geometry is a good solution to overcome such difficulties. Dimension is one of the important aspects in fractal structure design. According to Mandelbrot the fractal dimension is given by

work of all of the structure has been carried out using HFSS full wave simulator. II. Multi Band GP Patch Antenna A novel compact multiband fractal printed patch antenna using self-similar fractal structure has been reported [6]. In this section E-shape patch antenna has been modified by introducing GP fractal structure. This has been illustrated in Fig 1. The antenna is printed on two layers of dielectric materials. These are air at the bottom (1 mm height, r = 1) and FR4 at the top (5 mm height, r = 4.4, tan = 0.002). The overall dimension of the GP Antenna patch is 15 cm ? 13 cm with coaxial probe feeding and characteristics impedance of 50. The Fig. 2 shows the simulation results of the GP multi band patch antenna.

Fig. 1: CAD Model of the E Shape Patch Antenna and with Modified Fractal Structures.

D = lim log(N )

x0 log(x)

(1)

Where x = arbitrary unit length

N = how many times the unit length are using to cover the entire

length.

In the present paper, the GP fractal structure has been introduced

for miniaturization of both the antennas by using the following

formula with D = 1.8.

k1

(

1 h1

)D

+

k2

(

1 h2

)D

+ ......... +

kn

(

1 hn

)D

=1

(2)

Where hn is the ratio between the subsection length and the initiator length and kn is the number of subsections with the length ratio hn. The miniaturization in these antennas have been realized by some modification by GP structure in the antenna edges for fixed

D = 1.8. As a result, the overall antenna dimensions have been

reduced without altering their other characteristics. The simulation

Fig. 2: Comparison of Return Losses for 4 Different Structures

From fig. 2 one can observe that there is no such variation in multiband characteristics due to the fractal structure at the edges of the patch. Still it is possible to obtain three bands considering in the same position at about 1GHz, 2 GHz and 2.4 GHz. In case of the modified structure 3, one more operating band has been found at about 3.5 GHz. It can be considered to be an added advantage of using fractal structure in this case.



International Journal of Electronics & Communication Technology 69

IJECT Vol. 5, Issue Spl - 2, Jan - March 2014

ISSN : 2230-7109 (Online) | ISSN : 2230-9543 (Print)

Fig. 4: Three Different CAD Model Structure of the Antennas

Fig. 3: Simulated Radiation Pattern for the Proposed Antenna

Fig. 5: Comparison of Return Losses for 3 Different Patches Antennas Structure

The simulated radiation patterns of the proposed antenna's (structure 3 in fig. 1) four frequencies are depicted in fig. 3. Also, the bandwidth around there frequencies have been tabulated in Table 1.

Table 1: Different Bands in Proposed Antenna

Band

F1

F2

Bandwidth

(GHz)

(MHz)

Band I

.955

1.025

70

Band II 1.83

2.00

1.75

Band III 2.43

2.506

70

Band IV 3.44

3.626

186.7

Simulated S11 vs. frequency characteristics and the radiation pattern for the structure in the Fig .4 have been shown in Fig .5 and Fig.6 respectively. From the results, one can observed that, due to increase its iteration the operating frequency shifted down. Moreover the directivity also increased with the increasing in its iteration with no such degradation in antenna parameter. Comparing the antenna structure of the first and second iteration using GP fractal structure the second iteration structure is more acceptable due to its more miniaturized shape with less deviation in the antenna characteristics (Fig. 5) (Fig. 6).

From these results, one can observe that, there is no such degradation in antenna radiation pattern in all 4 different bands of structure 3. So it can be said that, the structure can be miniaturized by maintaining the antenna parameters.

III. Single Band GP Patch Antenna In the next part of the study, the simulation work has been started by using a square shape patch antenna. Subsequently its iteration has been increased using GP fractal structure at the edges of this square patch. This has been illustrated in fig. 4. The antenna has been designed on a FR4 substrate having dielectric constant of 4.4, tan = 0.002, height 1.6 mm. The dimension of the square patch is 30 mm ? 30mm. A coaxial probe feeding techniques are chosen here for antenna excitation with characteristics impedance of 50.

Fig. 6: Simulated Radiation Patterns for the Three Different Structures of the Antennas

70 International Journal of Electronics & Communication Technology



ISSN : 2230-7109 (Online) | ISSN : 2230-9543 (Print)

IV. Conclusion The Giuseppe Peano Fractal Structure exhibits an important improvement regarding antenna multiband and miniaturization process compare with the conventional patches. In Multiband GP Patch antenna we have achieved an extra band using a fractal structure around the edges compare with the ordinary E shape patch antenna without losing any antenna characteristics like return loss, radiation pattern etc. In the single band GP patch antenna we have miniaturize the antenna structure in large scale. So using the Giuseppe Peano Fractal structure geometry we are capable to miniaturize these basic two kinds of antenna without losing any antenna parameters.

References [1] D. H. Werner and S. Ganguly, "An overview of fractal antenna

engineering research," IEEE Antenna Propagat. Mag, Vol. 45, No. 1, pp. 38-57,Feb. 2003 [2] B.B.Mandelbort, "The Fractal Geometry of Nature" San Francisco,CA: Freeman, 1983, pp.152-ISO. [3] Rahmat-Samii, Y., Gianvittorio, J. P.,"Fractal Antennas: A novel antenna miniaturization technique and applications", IEEE Antennas and Propagation, Vol. 44, No. 1, February 2002, pp. 20 ? 36. [4] Homayoon Oraizi and shahram Hedayati, "Miniaturization of Microstrip Antennas by the novel Application of the Giuseppe Peano Fractal Geometries", IEEE Antennas and Propagation, Vol. 60, No. 8,B August 2012, pp. 3559 ?3567 [5] Y. B. Thakare,"Design of fractal patch antenna for size and radar crosssection reduction", IET Microwave and Antenna Propagation, Vol. 4, pp.175-181,2010. [6] NimaBayatmaku,ParisaLotfi,MohammadnaghiAzarmanesh, and Saber Soltani,"Design of Simple Multiband Patch Antenna for Mobile Communication Applications Using New E-Shape Fractal", IEEE Antennas and Propagation letters, Vol. 10.

IJECT Vol. 5, Issue Spl - 2, Jan - March 2014



International Journal of Electronics & Communication Technology 71

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