Dual Band Triangle Microstrip Patch Antenna with π shape Defected Ground Structure

Abstract

Proposed here is a dual band triangle micro strip patch antenna at 5.3GHz and π shape with defected ground structure resonate at 3.5GHz. Array Defected ground structure have been etched from the ground. Design and simulation is carried out with The CST V.12 simulator. This microstrip patch antenna for dual band frequency is designed with the help of defected ground structure to obtain a patch antenna with small dimensions and sufficient bandwidth as compared to conventional patch antenna .The effect of defected ground structure is shown in this paper.

Full text

Dual Band Triangle Microstrip Patch Antenna
with π shape Defected Ground Structure
Jean D. Habimana1, Felix Urimubenshi1, Sachin Sacharm1, Kumar Goodwill2, Sandeep Kr. Singh1
1Department of ECE, SET, Sharda University
2Department of ECE, IIT Roorkee
e-mail : 1habijadama@gmail.com, felruio@gmail.com , glasachin@yahoo.co.in
Abstract— Proposed here is a dual band triangle micro strip
patch antenna at 5.3GHz and π shape with defected ground
structure resonate at 3.5GHz. Array Defected ground
structure have been etched from the ground. Design and
simulation is carried out with The CST V.12 simulator. This
microstrip patch antenna for dual band frequency is
designed with the help of defected ground structure to obtain
a patch antenna with small dimensions and sufficient
bandwidth as compared to conventional patch antenna .The
effect of defected ground structure is shown in this paper.
Keywords- DGS antenna ,TMSA ,Insert cut feed.
I. INTRODUCTION
With the fast development of wireless communication, the
small multi-function terminal with multi-frequency bands has
attracted considerable interests of users, but the RF module
and antenna still occupy more than 60% size of the terminal at
present, how to reduce the dimension of the antenna in the
terminal has been very critical.[1]
At present many attractive characteristics of micro strip
patch antenna like low cost and compact for RF application
have made it a potential candidate in various wireless
communications [2]. As technology advances, devices become
more complex and antenna need to be also smaller .But the
most unique techniques to reduce the size and to enhance the
bandwidth of micro strip antenna is the Defected Ground
structure [3]. DGS offers dual band characteristic yielding a
high order matching network for bandwidth enhancement. So
designing an antenna with the defected ground structure
technique, the antenna size is reduced for a particular
frequency as compared to the antenna size without the defect
in the ground [4-6].
A. DEFECTED GROUNG STRUCTURE
DGS is an etched periodic or non–periodic cascaded
configuration defected in ground of planar transmission line
(e.g., micro strip, coplanar and conductor backed coplanar
wave guide) which disturbs the shield current distribution in
the ground plane cause of the defect in the ground. This
disturbance will change characteristic of transmission line
antenna design. DGS provides better matching options thus
reduces return loss and also helps to reduce the antenna size
and increase bandwidth [7, 8]. The design of the antenna is
inspired by DGS. The physical dimensions are provided
pictorially in fig1.
DGS has been widely used in the development of
miniaturized antennas. In, our design, DGS is a defect etched
in the ground plane that can give meta material behavior in
reducing the antenna size. DGS is basically used in micro strip
antenna design for different applications such as size
reduction, cross polarization reduction, mutual coupling
reduction in antenna arrays, harmonic suppression etc. DGS
are widely used in microwave devices to make the system
compact and effective [9-12].
Design of dual band antenna at 3.5GHz and 5.3GHz is
discussed in section II. Results are discussed in section III and
finally brief conclusion is given in section IV.
II. ANTENNA DESIGN
A. Triangle microstrip patch antenna with insert cut fed
The design of the antenna is inspired with and without
DGS. The physical dimensions are provided pictorially below.
Figure 1: Geometry and configuration of simple antenna
In Fig. 1 geometry of proposed antenna is having triangle
micro strip patch of side 19mm and the ground having the
dimensions 20mm × 20mm. Antenna is printed on a substrate
whose relative permittivity is 3.2 with loss tangent of 0.0024
and height is 1.524 mm. The micro strip insert cut feeding is
decided such that characteristic impedance of 50Ω is obtained.
The proposed antenna design for dual band incorporates a
shaped slot in Ground. The complete geometry of proposed π -
shaped DGS antenna is shown in Fig. 2

Figure 2 Geometry and configuration of proposed antenna with dual band using
DGS
III. RESULTS AND DISCUSSION
The antenna proposed will have two resonant parts, triangle
micro strip patch resonate at 5.3GHz and the π shape resonates
at 3.5GHz. The following figures are of resonance at these
frequencies with redness indicating higher resonance.
Simulations are carried out at CST V.2012.
Figure 3: Current density at 3.5 GHz
Figure 4: Current density at 5.3 GHz
While at 3.5 GHz (fig.2 upper) the patch is resonating, the π
shape resonance at 5.3GHz.
A. Radiation pattern
The radiation pattern is defined as a mathematic function or a
graphical representation of the radiation properties of space
coordinates. In most cases, the radiation pattern is determined
in the far –field region and is represented as function of the
directional coordinates [13].
Figure 5: Radiation patterns in 3D form at 3.5GHz
Figure 6: Radiation patterns in polar form at 3.5GHz
Figure 7: Radiation patterns in 3D form D at 5.3GHz

Figure 8: Radiation patterns in polar form at 5.3 GHz
Table 1.Comparative study of dual band micro strip patch
antenna using DGS
Parameters
Dual band using DGS
Simple
TMSA
Resonance
Frequency Fr
3.5GHz
5.3GHz
5.4GHz
Patch dimension
a= 18mm
a= 18mm
a= 19mm
Patch area
140.2 mm2
140.2 mm2
156.3 mm2
S11(return loss)
-27.8dB
-21.2dB
-25dB
Gain
4.2dB
5.8dB
6dB
B. S-Parameter (Return loss).
The S11 parameter for the proposed antenna was
calculated and the simulated return loss results are shown in
Figure 10. S11 the return loss, is a measure of the power
returned to the source [14].
Figure 9: Return loss of proposed antenna without DGS
Figure 10: Return loss of proposed antenna with dual band
The Dual band obtained is 3.5GHzand 5.3GHZ.So the main
intention of using defected ground structure is satisfied
IV. CONCLUSION
A dual frequency micro strip patch antenna has been
designed and simulated using CST Microwave Studio
software. This antenna resonates for the frequency band of 3.5
GHz and 5.3GHz. The corresponding value of return loss at
3.5GHz is -27.8dB and -21.2 dB for 5.3GHz which is enough
for matching. This return loss value i.e. -27.8dB and -21.2dB
suggests that there is good impedance matching at the
frequency point below the -10 dB region.
A broadside radiation pattern result has been obtained at
5.3GHz and for 3.5GHz was bi-directional and future work
will be focused to make it broadside radiation. This antenna
design with DGS reduces the radiating patch, which will cause
an overall reduction in antenna size. So the main intention of
using DGS is satisfied.
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