Design and development of a novel fractal antenna for wireless applications

IJRET: International Journal of Research in Engineering and Technology eISSN:2319-1163 | pISSN: 2321-7308
_______________________________________________________________________________________
Volume: 03 Issue: 11 | Nov-2014, Available @ http://www.ijret.org 188
DESIGN AND DEVELOPMENT OF A NOVEL FRACTAL ANTENNA
FOR WIRELESS APPLICATIONS
Manjit Kaur1
, Amandeep Singh2
, Kuldeep Sharma3
1
Department of ECE, RIET, Phagwara, Punjab, India
2
Dept.ECE, CTIEMT, Shahpur, Jalandhar, India
3
Department of ECE, RIET, Phagwara, Punjab, India
Abstract
An innovative concept is utilized to develop the fractal antenna by coalesce the Koch prefractal and meander line. This fractal
antenna is proposed for multistandard wireless applications. The shape and dimensions of the proposed antenna are chosen to
obtain the multiband behaviour as well as miniaturized structure. Initially two different fractal concepts have been chosen
through previous research and merged them to obtain more than two resonant frequencies. The proposed design characterizes
four bands at resonant frequencies 2.5 GHz, 6.4 GHz, 7.2 GHz and 8.15 GHz with a return loss of -12.05 dB, -16.68 dB, -14.87
dB and -26.51 dB respectively. This design also represents VSWR between the required range of 1 to 2 for the presented resonant
frequencies with an appropriate value of gain in dB. The antenna is analysed with Ansoft HFSS-13.0 electromagnetic field solver.
Keywords: Microstrip antennas, fractal antennas, miniaturized, multistandard, wireless applications
--------------------------------------------------------------------***------------------------------------------------------------------
1. INTRODUCTION
It has been observed from the recent literature that fractal
shape geometry concept can be utilized for the designing of
antennas. New antennas with miniaturized structure and
multistandard behaviour can be proposed as an outcome of
exclusive properties of fractals. Further enhancements in the
characteristics of antenna can be achieved by combining two
different types of fractals. Initially Mandelbrot has launched
the idea about “fractals” who expressed things that were too
asymmetrical to fit in conventional geometrical shapes.
Iterative function systems (IFS) are generally used to
develop the different fractal objects. The complexity of
fractal geometry depends upon the number of iterations and
due to this, fractals exhibit distinctive features such as space
filling characteristics and self-similarity. Here self-similarity
signifies that all the objects in antenna look approximately
the same at any scale. The space filling property generally
demonstrates the increase in electrical length of the antenna
elements. The longer paths for the surface currents
consequence in diminish the resonant frequencies without
overall extending the size of the resonator. Therefore, at a
desired frequency, the size of the antenna can be reduced as
compared to simple patch antennas. The fractal properties
have already been utilized to develop the new antennas and
in present research work we have attempted to unite two
different fractals such as Koch prefractal and meander line.
The innovation in the field of fractal antennas is progressing
day to day as Behdad et al. [1] presented a new method of
further reducing the size of an antenna and increasing the
bandwidth. They examined parasitic coupling and inductive
loading techniques to achieve higher bandwidths and further
size reduction. Moreira et al. [2] proposed microstrip fractal
antennas for multistandard terminals. They utilized Koch
prefractal edge and a U-shaped slot to design a
multistandard antenna for GSM 1800, UMTS, and
HiperLAN2 standards. Song et al. [3] demonstrated a
shorted fractal Sierpinski monopole antenna. This antenna
uses half structure of a traditional Sierpinski antenna and is
folded over to be parallel to the ground plane, to form an
element similar to that of the inverted L antenna. Quasi log
periodic resonance behaviour is obtained with a shorting pin
placed at the far end of the antenna. Sung et al. [4] improved
the design of microstrip patch antenna by using photonic
band gap structures in the substrate material to suppress the
surface waves. Singh et al. [5] proposed a miniaturized
wideband antenna where they utilized aperture coupling
feeding and inverted u-slot in patch to enhance the
bandwidth of antenna. huang et al. [6] demonstrated a novel
multiband and broadband fractal patch antenna which is
compact, simple to design and fabricate. The impedance
bandwidth of the proposed antenna could reach 18%, which
has rarely been reported for single layer and single patch
antennas. Singh et al. [7, 8] presented a design analysis of a
circular polarized slot loaded microstrip patch antenna for
multiband applications. Krishna et al. [9] proposed a dual
wide-band CPW-fed modified Koch fractal printed slot
antenna, suitable for WLAN and WiMAX operations.
Studies on the impedance and radiation characteristics of the
proposed antenna indicate that a modified Koch fractal slot
antenna has an impedance bandwidth from 2.38 to 3.95 GHz
and 4.95–6.05 GHz covering 2.4/5.2/5.8 GHz WLAN bands
and the 2.5/3.5/5.5 GHz WiMAX bands. Singh et al. [10]
discussed the multiband behaviour of plasmonic nano-
antennas for infrared and laser communication. Mondal et
al. [11] introduced a miniaturized and dual band hybrid koch
fractal dipole antenna design for different wireless
applications. In present work we have proposed a new
fractal antenna which exhibits a good value of return loss at
four resonant frequencies. The details of the development of
the proposed antenna are available in the next sections.

_______________________________________________________________________________________
2. DESIGN METHODOLOGY
To design and analyse the proposed antenna, High
Frequency structure Simulator (HFSS) electromagnetic
software tool is utilized. HFSS is a high performance full-
wave electromagnetic (EM) field solver for arbitrary 3D
volumetric passive device modelling. It integrates
visualization, simulation, solid modelling and automation in
an easy-to-learn environment where solutions to 3D EM
problems are quickly and accurately obtained [6]. Ansoft
HFSS employs the Finite Element Method (FEM), adaptive
meshing, and brilliant graphics to give unparalleled
performance and insight to all 3D EM problems. Ansoft
HFSS can be used to calculate parameters such as S-
Parameters, Resonant Frequency, and Fields. HFSS is an
interactive simulation system whose basic mesh element is a
tetrahedron thus allowing us to solve any arbitrary 3D
geometry.
3. ANTENNA DESIGN
Waclaw Sierpinski proposed one of the fractal geometry in
the year of 1916, which is now called as Sierpinski gasket
[21]. Similarly other different shapes have been developed
by the numerous researchers time to time. The concept of
combining two different geometries of fractal was initially
adopted during the year of 2002 to enhance the
characteristics of antenna. There are so many important
factors which decide the performance of the antenna and in
present research work these factors are different lengths and
widths as shown in the geometry of figure 1. Two individual
fractal geometries are basically adopted here as Koch
prefractal and meander line upto the second iteration. The
combination of these two fractals is responsible for
multiband behaviour as well as an acceptable value of gain.
The values of different lengths and widths have been
decided after proper parametric analysis to achieve the
appropriate target.
Fig 1: Geometry of the proposed fractal antenna
All the important design parameters of the proposed fractal
antenna are represented in form of table 1 which clearly
indicate the actual physical interpretation of the proposed
design
Table 1: Design parameters of the proposed antenna
Antenna Parameters Dimensions
W 27.00 mm
εr 4.4
h 1.58 mm
L1 16.50 mm
L2 1.50 mm
L3 2.50 mm
L4 1.50 mm
L5 2.50 mm
L6 11.00 mm
W1 11.50 mm
W2 2.00 mm
W3 1.00 mm
W4 0.50 mm
W5 2.80 mm
W6 2.00 mm
W7 1.50 mm
W8 3.00 mm
4. RESULTS AND DISCUSSIONS
The proposed fractal antenna geometry has been
demonstrated through figure 1 and all the significant
parameters are described through table no. 1 with their
values in „mm‟. The important technique to analyse the
performance of the antenna is its parametric analysis.
Parametric analysis has been done by taking into
consideration two valuable parameters i.e. substrate
thickness „h‟ and side length of the meander like structure.
Fig 2: Return Loss versus operating frequency
characteristics of proposed antenna by variation in substrate
thickness „h‟

_______________________________________________________________________________________
Figure 2 represents the return loss versus operating
frequency characteristics of the proposed antenna by varying
the substrate thickness which is ranging between 0.75 mm
and 2.41 mm. It is observed from the figure 2 that if the
value of „h‟ is taken to be 0.75 mm, the antenna resonates at
frequencies 6.1 GHz, 6.40 GHz and 7.77 GHz at a
corresponding return losses of -16.76 dB, -18.02 dB and -
22.84 dB. This is represented by black line of figure 2. With
a certain change in „h‟ value from „0.75 mm‟ to „1.6 mm‟
the resonant frequencies are modified as 6.07 GHz, 6.48
GHz and 7.81 GHz with corresponding return loss values -
25.11 dB, -12.88 dB and -19.40 dB. Further if the „h‟ value
is increased to 2.41 mm the antenna resonates at frequencies
6.11 GHz, 6.70 GHz and 7.81 GHz with the return loss
values -10.95 dB, -9.94 dB and -10.14 dB respectively. this
is represented by blue line curve of figure 2. From the above
said discussion about the „h‟ parameter of the proposed
antenna it has observed that its value should be 1.6 mm at
which it resonates absolutely at specific values of return
loss. For the convenience of the reader the results of figure 2
related to the „h‟ parameter analysis are tabulated in table 2.
After setting the value of substrate height/thickness („h‟ in
mm) another important parameter has taken into
consideration i.e. side length of meander like structure „L1‟.
The parametric analysis of side length „L1‟ is demonstrated
through figure 3. At first step the parameter „L1‟ has taken
to be 16.05 mm and at this value the proposed antenna
resonates at operating frequencies 2.81 GHz, 6.85 GHz, 6.96
GHz and 8.59 GHz with return loss values -11.24 dB, -18.11
dB, -10.22 dB and -26.82 dB respectively. This is
represented by black line of figure 3. Now if we increase the
side length „L1‟ value from 16.05 mm to just 16.50 mm the
antenna resonates at operating frequencies 2.81 GHz, 6.81
GHz, 7.33 GHz and 8.55 GHz with return loss values of -
14.3 dB, -17.43 dB, -15.05 dB and -29.01 dB respectively.
This is represented by red curve plot of figure 3.
Table 2: Resonant frequencies and return loss
characteristics at different values of substrate height
Substra
te
height
in mm
Fr
in
GH
z
S11 in
dB
Fr
in
GH
z
S11
in dB
Fr
in
GH
z
S11 in
dB
0.75 6.1 -16.76 6.40
-
18.0
2
7.77 -22.84
1.6 6.07 -25.11 6.48
-
12.8
8
7.81 -19.40
2.41 6.11 -10.95 6.70 -9.94 7.81 -10.14
Fig 3: Return Loss versus operating frequency
characteristics of proposed antenna by variation in side
length „L1‟
Further operating frequencies are shifted to 2.92 GHz, 6.85
GHz, 7.29 GHz and 8.56 GHz at return loss values of -5.84
dB, -15.13 dB, -13.96 dB and -19.89 dB respectively when
side length „L1‟ value assumed as 17.05 mm. It is
represented through blue curve plot of figure 3. It is not easy
to recognize the operating frequencies and corresponding
return loss values through line plots of figure 3 therefore, the
consolidated results of figure 3 are also demonstrated in
table 3.
Table 3: Resonant frequencies versus return loss characteristics for different L1 lengths
Length L1
in mm
Fr in
GHz
S11 in dB
Fr in
GHz
S11 in dB
Fr in
GHz
S11 in dB
Fr in
GHz
S11 in dB
16.05
2.81 -11.24
6.85 -18.11 6.96 -10.22 8.59 -26.82
16.5
2.81 -14.3
6.81 -17.43 7.33 -15.05 8.55 -29.01
17.05
2.92
-5.84 6.85 -15.13 7.29 -13.96 8.56 -19.89

_______________________________________________________________________________________
Finally it is observed from the above discussion about the
parametric analysis that the substrate thickness/height and
side length „L1‟ of meander like structure are chosen to be
„1.6 mm‟ and „16.5 mm‟ respectively. The analysis of
antenna is generally based upon two broad categories, one is
input parameters and another is output parameters. Return
loss characteristics as shown in figure 2 and figure 3 are
representing the input characteristics and gain of the antenna
comes under the output characteristics. Therefore, it is
important to analyse the gain response of the proposed
antenna to confirm the antenna as a good radiator. Figure 4
is representing the 3D gain plot of the proposed antenna
which shows that the antenna is radiating maximally normal
to the plane of conductive patch. The peak gain achieved
through the proposed antenna design is approximately 6.73
dB.
Fig 4: 3D gain plot of the proposed fractal antenna design
5. CONCLUSION
Exclusive fractal geometry is proposed for antenna. Initially
some of the important parameters have taken into
consideration for parametric analysis and the optimum
values of these parameters are obtained. Further the fractal
antenna geometry is analysed to know the characteristics of
antenna. It has observed that the proposed antenna is
multiband in nature and exhibiting resonant frequencies of
2.81 GHz, 6.81 GHz, 7.33 GHz and 8.55 GHz with return
loss values of -14.3 dB, -17.43 dB, -15.05 dB and -29.01 dB
respectively. Return loss is generally comes under the
category of input characteristics and it is also important to
understand the radiating behaviour of proposed antenna
design. The radiating behaviour can be checked through the
gain parameter of the antenna and in present work the
proposed design demonstrated a gain of 6.73 dB which is a
very good value for such type of minute antenna. It is
concluded with reference to the discussion held on that the
proposed antenna suitably address the wireless applications
such as WiMAX band, Radio astronomy, Passive sensor
networks and high speed applications.
REFERENCES
[1] Naded Behdad and Kamal Sarabandi, “Bandwidth
Enhancement and Further Size Reduction of a Class
of Miniaturized Slot Antennas,” IEEE Transactions
on Antennas and Propagation, Vol. 52, No. 8, pp.
1928-1935, 2004.
[2] Jerzy Guterman, António A. Moreira and Custódio
Peixeiro, “microstrip fractal antennas for
multistandard terminals,” IEEE Antennas and
Wireless Propagation Letters, Vol. 3, pp. 351–354,
2004.
[3] C. T. P. Song, Peter S. Hall, H. Ghafouri-Shiraz,
“Shorted Fractal Sierpinski Monopole Antenna,”
IEEE Transactions on Antennas and Propagation,
Vol. 52, No. 10, pp. 2564-2569, Oct. 2004.
[4] Y. J. Sung and Y.-S. Kim, “An Improved Design of
Microstrip Patch Antennas Using Photonic Bandgap
Structure,” IEEE Transactions on Antennas and
Propagation, Vol. 53, No. 5, pp. 1799-1804, 2004.
[5] Amandeep Singh and Surinder Singh, “Miniaturized
Wideband Aperture Coupled Microstrip Patch
Antenna by Using Inverted U-Slot,” International
Journal of Antennas and Propagation (Hindawi
Publishing Corporation), Vol. 2014, Article ID
306942, pp. 1-7, 2014.
[6] J. J. Huang, F. Q. Shan and J. Z. She, “A Novel
Multiband and Broadband Fractal Patch Antenna,”
Progress In Electromagnetics Research Symposium,
USA, pp. 57-59, 2006.
[7] Jatinderpal Singh, Amandeep Singh and Nancy
Gupta, “Design Analysis of a Hexaband Slot Loaded
Microstrip Patch Antenna using ANN,”
International Journal of Computer Applications, vol.
101, No. 14, pp. 7-12, 2014.
[8] Jatinderpal Singh, Amandeep Singh and Nancy
Gupta, “Design Analysis of a Circular Polarized Slot
Loaded Microstrip Patch Antenna for Multiband
Applications,” International Journal of Information
& Communication Technology, vol. 2, pp. 35-40,
2014.
[9] Deepti Das Krishna, M. Gopikrishna, C. K.
Anandan, P. Mohanan and K. Vasudevan, “CPW-
Fed Koch Fractal Slot Antenna for WLAN/WiMAX
Applications,” IEEE Antennas and Wireless
Propagation Letters, Vol. 7, pp. 389–392, 2008.
[10] Bhupinder Singh, Amandeep Singh and Hardeep
Singh, “Plasmonic Nano-Antennas for Infrared and
Laser Communication,” International Journal of
Information & Communication Technology, vol. 1,
pp. 27-31, 2013.
[11] Arpan Mondal, Sandeep Chakraborty, Rajiv K
Singh and Rowdra Ghatak, “Miniaturized and Dual
Band Hybrid Koch Fractal Dipole Antenna Design,”
in proceedings of International Conference on
Computer, Communication and Electrical
Technology – ICCCET 2011, pp 193-197, 2

Design and development of a novel fractal antenna for wireless applications

More Related Content

What's hot (20)

Similar to Design and development of a novel fractal antenna for wireless applications (20)

More from eSAT Journals (20)

Recently uploaded (20)

Design and development of a novel fractal antenna for wireless applications