International Journal of
Electronics and
Engineering
& Technology
(IJECET), ISSN
INTERNATIONAL
JOURNAL
OFCommunication
ELECTRONICS
AND
COMMUNICATION
0976 – 6464(Print),ENGINEERING
ISSN 0976 – 6472(Online)
Volume
3,
Issue
2,
July-September
(2012),
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IAEME
& TECHNOLOGY (IJECET)
ISSN 0976 – 6464(Print)
ISSN 0976 – 6472(Online)
Volume 3, Issue 2, July- September (2012), pp. 445-450
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IJECET
©IAEME
SIZE REDUCTION AND MULTIBAND OPERATION OF RHOMBUS
SHAPED FRACTAL MICROSTRIP ANTENNA FOR WIRELESS
APPLICATIONS
Jagadeesha.S1, Vani R.M2, P.V Hunugund3
Department of Electronics & Communication, S.D.M Institute of Technology,
Ujire-574240, India
2
University of science & Instrumentation centre, Gulbarga University,
Gulbarga- 5851006, India
3
Department of Applied Electronics, Gulbarga University, Gulbarga-5851006, India
[email protected], [email protected],
[email protected]
1
ABSTRACT
The design and study of 2.4 GHz (ISM band) rhombus shaped Microstrip antenna along with
fractal geometry is made. A fractal antenna shows multiband behavior due to self –similarity
in their geometrical structure. The proposed fractal antenna resonates at 1.72 GHz with zeroth
iteration and resonates at 1.37 GHz with first iteration respectively. Thus the size reduction of
68.96 % with overall bandwidth of 380MHz is obtained. Simulation is carried out using IE3D
software and it is found that simulated results are in good agreement with experimental
results.
Keywords: Rhombus shape antenna, fractal geometry, multi band antenna, size
reduction, IEEE 802.11 WLAN applications.
I INTRODUCTION
The tremendous development in communication field accelerates to increase in wireless
devices and systems to ascertain wireless connectivity between devices [1,2]. One of the
techniques used to decrease the antenna’s dimensions is application of fractal geometries.
This necessitated in developing a compact multiband antenna, which is essential for wireless
applications to satisfy the needs. The frequency 2.4GHz is intended for IEEE 802.11 WLAN
applications. Dual band or multiband antenna is a solution for such wireless applications [3][7]. Fractal geometry on microstrip antenna is apted for absorbing less volume on wireless
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International Journal of Electronics and Communication Engineering & Technology (IJECET), ISSN
0976 – 6464(Print), ISSN 0976 – 6472(Online) Volume 3, Issue 2, July-September (2012), © IAEME
boards [8].The booming progress of wireless systems and the dramatic development of a
variety of wireless applications have remarkably increased the demand for
multiband/wideband antennas. While traditionally different antennas are used for different
frequency bands, recent studies have suggested that small planar antennas of certain
configurations may operate in several frequency bands at a time. Further efforts in combining
geometry with electromagnetic theory have led to many innovative antenna designs and, in
particular, to the development of the rapidly growing field of 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. The primary active area of research in fractal antenna engineering
is the study of fractal-shaped antenna elements. Fractal are a class of shapes which have not
characteristic size, each fractal is composed of multiple iterations of a single elementary
shape. The iteration can continue infinitely thus forming a shape within a finite boundary but
of infinite length or area [9].
Fractal means broken or irregular fragments. Fractals describe a complex set of geometries
ranging from self-similar Self-affine to other irregular structure. Fractals are generally
composed of multiple copies of themselves at different scales and hence do not have a
predefined size which makes their use in antenna design very promising [10]. In this paper,
we use rhombus shaped fractal Microstrip antenna for multiband operations. With first
iteration the antenna is giving more size reduction along with enhanced bandwidth.
II
ANTENNA DESIGN
The Rhombus shaped fractal microstrip antenna which is considered as base shape i.e., with
zeroth iteration as shown in figure 1(a) whose size is of 41 mm *41mm is printed on a
dielectric substrate of thickness 1.6mm.The material used is glass epoxy with dielectric
permittivity of €r=4.4 which is desired to operate at 2.4GHz. This designed antenna is fed by
microstrip line of dimension (Lf50, Wf50) = 15mm, 4.84mm through quarter wave
transformer having (Lt50, Wt50) = 24.05mm, 0.72mm. They are mounted on ground plane of
dimension 106 mm * 67.6mm through 50 ohm SMA connector. In fractal geometry the curve
is characterized by two factors: the iteration factor and iteration number. The iteration factor
represents the construction law of fractal geometry, and iteration number depicts how many
iteration processes is carried out. The rhombic shape of zeroth iteration is a conventional
square. In zeroth iteration, this curve begins as a straight line imposed upon the sides of the
square. Next, another square of side length each conventional square line length times the
iteration factor that lies at the center of each side of the square is removed. The geometry of
this process is called the first iteration patch as illustrated in figure 1(b). Here the iteration
factor considered is ¼. The base antenna with zeroth iteration and antenna with first iteration
are fabricated and photos of antenna are shown in fig 2(a) and 2(b) respectively. These
antennas are initially simulated using IE3D software and all the parameters are optimized and
they are as follows:
h=1.6mm, L=41.08mm,W=41.08mm,Ls=10.27mm,Ws=10.27mm,Lt=24.05mm,
Wt=0.72mm, Lf=15mm,Wf=4.84mm.
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International Journal of Electronics and Communication Engineering & Technology (IJECET), ISSN
0976 – 6464(Print), ISSN 0976 – 6472(Online) Volume 3, Issue 2, July-September (2012), © IAEME
Fig.1(a) Geometry of
base antenna
Fig.2 (a) Fabricated view of base antenna
with top and bottom view
Fig.1(b) Geometry of
base with first iteration
Fig.2 (b) Fabricated top and bottom view
of base antenna with first iteration
3. RESULTS AND DISCUSSIONS
Rhombus shaped microstrip fed fractal antenna were examined using IE3D simulation tool.
The return loss characteristics with different iterations of the rhombus shape fractal antenna
are measured and it is compared with simulated results which are shown in fig.3 and fig.4
respectively. The results have been verified practically by using vector network analyzer
model Rohde and schowrz, German make ZVK model No.8651. Simulated results are in good
agreement with experimental results. The resonant frequencies of the zeroth iteration patch
i.e., base patch is operating at 1.71Ghz, 2.43Ghz, 3.44Ghz, 3.99Ghz and 4.94 Ghz
respectively. In case of First iteration patch is resonating at 1.37 GHz, 1.58 GHz, 2.67 GHz,
3.07 GHz and 4.92 GHz respectively. After First iteration, the resonant frequency shifts to
lower side significantly as summarized in Table.1. With this we have achieved good size
reduction of about 68.96% to that of conventional base antenna. From the result it is clear that
the proposed antenna is giving multi frequencies with iterations. Also the simulated and
measured bandwidth at each frequency is mentioned in table 1.The overall bandwidth of base
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International Journal of Electronics and Communication Engineering & Technology (IJECET), ISSN
0976 – 6464(Print), ISSN 0976 – 6472(Online) Volume 3, Issue 2, July-September (2012), © IAEME
antenna is 290 MHz and with first iteration is 380 MHz. So, the bandwidth of the antenna is
enhanced with first iteration.
Fig 3. Return loss characteristics of base antenna or zeroth iteration antenna.
Fig.4: Return loss characteristics of Antenna with first iteration
Then the radiation pattern for both the antennas has been studied by using IE3D. The fig 5(a)
shows the radiation pattern of conventional base antenna at 1.72 GHz and fig 5(b) shows the
radiation pattern of antenna with first iteration at 1.37 GHz. It is observed that all radiation
patterns are broadside.
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International Journal of Electronics and Communication Engineering & Technology (IJECET), ISSN
0976 – 6464(Print), ISSN 0976 – 6472(Online) Volume 3, Issue 2, July-September (2012), © IAEME
(a)
(b)
Fig 5: Simulated radiation pattern at (a) 2.44GHz for conventional base antenna
(b) 1.37GHz for first Iteration.
Table 1: Results of proposed antennas
IV CONCLUSION
This paper presents a new Rhombus shaped microstrip antenna with fractal geometry. This
antenna supports the multiband operation. From the
results we can conclude that the
rhombus shaped fractal antenna gives size reduction of 50.97 % with overall bandwidth of
290 MHz. Also with first iteration there is an enhancement in overall bandwidth to 380MHz
449
International Journal of Electronics and Communication Engineering & Technology (IJECET), ISSN
0976 – 6464(Print), ISSN 0976 – 6472(Online) Volume 3, Issue 2, July-September (2012), © IAEME
and increase in size reduction to 68.96%. The practical results are in good agreement with
simulated results.
REFERENCES
[1] Y.-B. Kwon, J-I. Moon, and S.-O.Park, 2003. “An internal triple-band planar inverted –F
antenna,” IEEE antennas Wireless Prop.Lett., vol.2, pp.341-344.
[2] M.-C.Huynh and W.L. Stutzman, Jul.2004. “A low- profile compact multi-resonant
antenna for wideband and multi-band personal wireless applications”, in Proc. IEEE AP-S Int.
Symp, vol.2, pp.1879-1882.
[3] Y.Cao, C.Lu, and Y.Zhang, Apr.2008. “A Compact dual band miniaturized antenna for
WLAN operation,” in Proc, ICMMT, pp.416-419.
[4] Q.He.B Wang, and J.He, 2008. “Wideband and dual-band design of a printed dipole
antenna,”IEEE Antennas Wireless .Lett, vol.7, pp.1-4.
[5] R.Li, B.Pan.J. Laskar, and M.M. Tentzris, Apr. 2008. “A Novel low- profile broadband
dual frequency planar antenna for wireless handsets,” IEEE Trans, Antennas Prop., vol.
56.No:4, pp.1155-1162.
[6] M.N. Suma, R.K.Raj.M.Joseph, P.C.Bybi, and P.Mohanan, May.2006. “A Compact dual
band planar branched monopole antenna for DCS/2.4-GHz WLAN applications,” IEEE
Microw. Wireless Compo. Lett, vol.16.No.5.pp.275-277.
[7] M.J. Kim. C.S. Cho, and J.Kim, Dec.2005. “A dual band printed dipole antenna with
spiral structure for WLAN application,” IEEE Microw. Wireless comp on Lett. Vol.15 No;
12, pp.910-912.
[8] G. Srivatsun, Subha Rani, “A Compact Multiband Fractal Cantor Antenna for Wireless
Applications” European Journal of Scientific Research, ISSN 1450-216X Vol.71 No.2 (2012),
pp. 273-282, © EuroJournals Publishing, Inc. 2012
[9] Kulbir singh, Vinit Grewal and Ragiv Saxena “International Journal of Recent Trends in
Engineering” Vol 2, No.5 pp.172-176, November 2009
[10]Ananth Sundaram, Student Member, IEEE, Madhurima Maddela, Student Member,
IEEE, and Ramesh Ramadoss, Member, IEEE “Koch-Fractal Folded- Slot Antenna
Characteristics” IEEE Antennas and wireless propagation letters Vol.6, 2007.
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