Design and optimization of microstrip patch antenna with

IJRET: International Journal of Research in Engineering and Technology eISSN: 2319-1163 | pISSN: 2321-7308
__________________________________________________________________________________________
Volume: 02 Issue: 07 | Jul-2013, Available @ http://www.ijret.org 183
DESIGN AND OPTIMIZATION OF MICROSTRIP PATCH ANTENNA WITH
DEFECTED GROUND STRUCTURE & CIRCULAR SLOT ON THE PATCH
Vandana Chopra1
, Maninder Kaur2
, K.V.P Singh3
, Sumit Kumar Jha4
Doaba Institute of Engineering & Technology, Kharar, Mohali, Punjab, vandana_yng@yahoo.com
Abstract
A single feed compact rectangular micro strip patch antenna (MSA) for triple band application is presented in this paper. The
proposed antenna has Circular slot on the patch and dumble shaped defected ground structure (DGS). To make the proposed antenna
more efficient the optimization of the antenna design parameters have been done using HFSS’s optometric. For the proposed antenna
three resonant frequencies have been obtained at 2.33GHz, 7.60GHz and 8.53GHz with Bandwidth of 102Mz,130MHz and 127MHz
return loss of -15.80db ,-18.77db and -36.57db respectively. The characteristics of the designed structure are investigated by using
FEM based electromagnetic solver, HFSS. An extensive analysis of the return loss, gain and bandwidth of the proposed antenna is
presented. The simple configuration and low profile nature of the proposed antenna leads to easy fabrication and make it suitable for
the application in wireless communication systems. Mainly it is developed to operate in the WLAN, WiMAX & RADAR application.
Key Words: Bandwidth, Return loss, Patch, DGS, RADAR
----------------------------------------------------------------------***---------------------------------------------------------------------
1. INTRODUCTION
Microstrip antennas are very attractive because of their low
profile, low weight, conformal to the surface of objects and
easy production. A large number of microstrip patches to be
used in wireless applications have been developed [1-3].
Design of WLAN antennas also got popularity with the
advancement of microstrip antennas [4-5]. Wireless local area
network (WLAN) requires three band of frequencies: 2.4GHz
(2400-2484MHz), 5.2GHz (5150-5350MHz) and 5.8GHz
(5725-5825MHz). WiMax has three allocated frequency
bands. The low band (2.5-2.69GHz), the middle band (3.2-3.8
GHz) and the upper band (5.2-5.8GHz).Tele communication
via satellite and RADAR use the 4-8GHz band of frequency.
The size of antenna is effectively reduced by cutting slot in
proper position on the microstrip patch. The use of DGS for
size reduction of microstrip antenna, although its application
has been reported for harmonic reduction [6], cross-
polarization suppression [7] and mutual coupling reduction [8]
in antenna arrays etc. This paper presents the application of
dumble shaped defected ground structure (DGS) in microstrip
antenna for size reduction and to achieve useful multiband.
While maintaining the antenna size, the broader operating
bandwidth (BW) [9,10] is realized by cutting the slots of either
half wave or quarter wave in length, having different shapes
like U-slot, V-slot, L-slot, and a pair of rectangular slots inside
the patch [11,12]. In this paper T-slot has been presented. The
slot introduces a mode near the fundamental mode of the patch
and realizes broadband response.
2. CONVENTIONAL MSA DESIGN, RESULTs &
ANALYSIS
The design of the antenna is shown in figure 1(a). The antenna
has 29mm x 25mm rectangular patch. The dielectric material
selected for this design with εr = 4.4 and substrate height
=1.57mm. The antenna has been designed using the
transmission line model. Where the transmission line model is
most accurate To design the conventional rectangular micro
strip patch antenna that operates at frequency around
2.45GHz, the dimensions can be found using [3]:
Step 1: Determination of the Width (W).The width of the
Microstrip patch antenna is given by [3]
W = 37.26mm.
Step 2: Determination of effective dielectric constant (εreff). The
effective dielectric constant is represented by [3]. By substituting εr
= 4.4, W = 36.26 mm and h = 1.57 mm, it can be determined that
εreff = 4.4.
Step 3: Determination of the effective length (Leff) The effective
length is given by [3]. By substituting εreff = 4.4, c = 3×10^8 m/s
and f0 = 2.45 GHz, it can determine that
Leff = 29.126 mm.
Step 4: Determination of the length extension (ΔL) [3]
The length extension may be represented by substituting εreff = 4.4,
W = 36.26 mm and h = 1.57 mm, it can be determined that
ΔL = 0.01634 mm.
Step 5: Determination of actual length of patch (L):
The actual length is obtained by using expression
L = Leff -2ΔL

__________________________________________________________________________________________
By substituting Leff = 29.126 mm and ΔL = 0.01634 mm, the
actual length can determined as
L = 29.093 mm
The actual length of the patch has been found using [3].
Now from the above calculated data antenna has been
designed on HFSS 13.0. The design is shown in figure below:
Figure 1(a): Conventional Microstrip Patch Antenna Design
Figure 1(b): S-Parameter plot of the conventional Microstrip
Patch Antenna
In the figure 1(b) the S-parameter plot of the MSA design of
figure1(a) is shown and from the plot we can easily calculate
the bandwidth as well as returnloss which are at 2.43GHz,
3.82GHz, 4.64GHz, 6.27GHz, 7.17GHz, 9.16GHz and
9.54GHz and bandwidth of 77MHz, 78MHz, 68MHz, 77MHz,
112MHZ and 112 MHz were obtained respectively. Due to the
presence of the multiple bands as well as presence of so many
numbers of varying amplitudes this antenna will consume too
much power and hence will not radiate effectively on the
particular selected band.
3. MSA with CIRCULAR slot and DGS- DESIGN,
RESULTs & aNALYSIS
Now the patch antenna has been improved with the Circular
slot on the rectangular patch which is shown in figure2 (a) and
the ground have been made defected with the dumble shaped
defected ground structure as shown in figure 2(b).
Figure 2(a): Simulated Design of Triple Band MSA (Front
View showing Circular slot)
Figure 2(b): Simulated Design of Triple Band MSA (Back
View showing DGS)
The fronts view of the antenna shows the Circular slot which
is made by etching the patch. The defected ground structure
has been made on the ground of the patch antenna which has
dumble shape by etching the ground plane. The antenna
parameter is given in table below:
Table 1: Dimensions of the Microstrip Patch Antenna
Variable Value
Length of the Patch(lp) 25.054mm
Width of the Patch(wp) 29.036mm
Thickness of the Patch(t) 0.035mm
Width of the Ground(wg) 21.056mm
Length of the Ground(lg) 34.874mm
Width of the Substrate(ws) 41.456mm
Length of the substrate(ls) 34.874mm
Height of the Substrate(h) 1.57mm
Dimension of the symmetrical
rectangular box on the ground
6.5mm,4.5mm
Dimension of rectangular box
connector on the ground
2.5mm.1mm
Width of the feed Line(wf) 0.8mm
Radious of Circle on Patch 5mm
1.00 2.00 3.00 4.00 5.00 6.00 7.00 8.00 9.00 10.00
Freq [GHz]
-25.00
-20.00
-15.00
-10.00
-5.00
0.00
dB(S(p1,p1))
HFSSDesign1XY Plot 1 ANSOFT
m1
m2
m3
m4
m5
m6
m7
m8m9 m10m11 m12m13 m14m15
m16
m17 m18m19
Curve Info
dB(S(p1,p1))
Setup1 : Sw eepName X Y
m1 2.4350 -15.2698
m2 3.8220 -18.8795
m3 4.6470 -12.5699
m4 6.2780 -12.0942
m5 7.1730 -13.7811
m6 9.1610 -23.4725
m7 9.5470 -14.8572
m8 3.7830 -9.9500
m9 3.8600 -10.1159
m10 4.6160 -10.1492
m11 4.6940 -10.0327
m12 6.2410 -9.9187
m13 6.3090 -10.0819
m14 7.1370 -9.9513
m15 7.2140 -10.0013
m16 9.1060 -9.6058
m17 9.2180 -10.0614
m18 9.4840 -9.9289
m19 9.5960 -10.1142
Name Delta(X) Delta(Y) Slope(Y) InvSlope(Y)
d(m8,m9) 0.0770 -0.1659 -2.1549 -0.4641
d(m10,m11) 0.0780 0.1165 1.4938 0.6694
d(m12,m13) 0.0680 -0.1632 -2.4007 -0.4165
d(m14,m15) 0.0770 -0.0500 -0.6492 -1.5405
d(m16,m17) 0.1120 -0.4556 -4.0677 -0.2458
d(m18,m19) 0.1120 -0.1853 -1.6542 -0.6045

__________________________________________________________________________________________
Figure 2(c): S-Parameter plot of the MSA with DGS and
Circular Slot
In the figure 2(c) the S-parameter plot of the MSA design of
figure2 is shown and from the plot we can easily calculate the
bandwidth and returnloss which are (98MHz,-14.55db),
(217MHz, -16.64db) at 2.30GHz and 8.92GHz respectively.
4. OPTIMIZATION OF MSA
To get the best possible result the antenna has been optimized
in a number of ways. Here optimizations of the patch antenna
is Discussed.
Width Optimization
Here the width of the microstrip patch antenna have been
optimized, the width of patch (WP), the width of ground (wg)
and the width of substrate (ws) have been simultaneously
optimized.
Table2: Width optimization
Variation wg wp ws
1 21mm 21mm 21mm
2 21mm 22mm 21mm
3 21mm 23mm 21mm
4 21mm 24mm 21mm
5 21mm 25mm 21mm
6 21mm 26mm 21mm
7 21mm 27mm 21mm
8 21mm 28mm 21mm
9 21mm 29mm 21mm
10 21mm 21mm 22mm
11 21mm 22mm 22mm
12 21mm 23mm 22mm
13 21mm 24mm 22mm
14 21mm 25mm 22mm
15 21mm 26mm 22mm
16 21mm 27mm 22mm
17 21mm 28mm 22mm
18 21mm 29mm 22mm
19 21mm 21mm 23mm
20 21mm 22mm 23mm
21 21mm 23mm 23mm
22 21mm 24mm 23mm
23 21mm 25mm 23mm
24 21mm 26mm 23mm
25 21mm 27mm 23mm
26 21mm 28mm 23mm
Figure 3(a): S-Parameter plot of the MSA with DGS and
Circular Slot in Width Optimization
From this analysis the best width combination has been
selected and now Radious of the circular slot on the patch
have been optimized.
Radious Optimization
Now the Radious of the microstrip patch antenna have been
optimized to get the best possible result.
Table 3: Radious Optimization
Variation rad
1 2mm
2 3mm
3 4mm
4 5mm
5 6mm
6 7mm
7 8mm
8 9mm
9 1mm
Now the plots have been taken on all the variations and the
obtained accumulated plot is shown in figure below:
1.00 2.00 3.00 4.00 5.00 6.00 7.00 8.00 9.00 10.00
Freq [GHz]
-17.50
-15.00
-12.50
-10.00
-7.50
-5.00
-2.50
0.00
dB(S(p1,p1))
m1
m2
m3m4 m5 m6
Curve Info
dB(S(p1,p1))
Setup1 : Sw eep
ls='34.874mm'
Name X Y
m1 2.3020 -14.5506
m2 8.9230 -16.6466
m3 2.2530 -9.8809
m4 2.3510 -9.9714
m5 8.8190 -9.9814
m6 9.0360 -9.9271
d(m3,m4) 0.0980 -0.0905 -0.9239 -1.0823
d(m5,m6) 0.2170 0.0543 0.2502 3.9975
1.00 2.00 3.00 4.00 5.00 6.00 7.00 8.00 9.00 10.00
Freq [GHz]
-45.00
-40.00
-35.00
-30.00
-25.00
-20.00
-15.00
-10.00
-5.00
0.00
dB(S(p1,p1))
Curve Info
dB(S(p1,p1))
Setup1 : Sw eep
ls='34.874mm'
dB(S(p1,p1))
Setup1 : Sw eep
ls='34.874mm'
dB(S(p1,p1))
Setup1 : Sw eep
ls='34.874mm'
dB(S(p1,p1))
Setup1 : Sw eep
ls='34.874mm'
dB(S(p1,p1))
Setup1 : Sw eep
ls='34.874mm'
dB(S(p1,p1))
Setup1 : Sw eep
ls='34.874mm'
dB(S(p1,p1))
Setup1 : Sw eep
ls='34.874mm'
dB(S(p1,p1))
Setup1 : Sw eep
ls='34.874mm'

__________________________________________________________________________________________
Figure 3(a): S-Parameter plot of the MSA with DGS and
Circular Slot in Radious Optimization
5. OPTIMIZED MICROSTRIP PATCH ANTENNA
RESULTs & ANALYSIS
Now the microstrip patch antenna has been optimized in all
the possible ways to get the best possible results and final
results are presented in this section.
Table4: Optimized dimensions of the proposed MSA
Variable Value
Length of the Patch(lp) 25.054mm
Width of the Patch(wp) 21mm
Thickness of the Patch(t) 0.035mm
Width of the Ground(wg) 21 mm
Length of the Ground(lg) 34.874mm
Width of the Substrate(ws) 22mm
Length of the substrate(ls) 34.874mm
Height of the Substrate(h) 1.57mm
Dimension of the symmetrical
rectangular box on the ground
6.5mm,4.5mm
Dimension of rectangular box
connector on the ground
2.5mm.1mm
Width of the feed Line(wf) 0.8mm
Radious of Circle on Patch 1mm
Now figure below shows all the plots that have been taken.
Figure 4(a): S-Parameter plot of the Optimized MSA with
DGS and Circular Slot on the patch
Figure 4(b): 3D-Polar plot of the Optimized MSA with DGS
and Circular Slot on the patch
Figure 4(c): Radiation Pattern plot of the Optimized MSA
with DGS and Circular Slot on the patch
In the figure 4(a) the S-parameter plot of the MSA design of
figure4 is shown and from the plot we can easily calculate the
bandwidth and returnloss which are (102MHz -15.08db),(
130MHz -18.77db) & ( 127MHz -36.57db) at
2.33GHz,7.60GHz,8.53GHz respectively.
6. COMPARISIONS & CONCLUSIONS
Table5: Table of Comparisons
Frequencies(
GHz)
Returnloss(db
)
Bandwidth
(MHz)
-15.26db, -
18.87db,
-12.56db,-
12.09db,
-13.78db,-
23.47db,
-14.85db.
Design
With
Circular
Slot on
the patch
and DGS
2.30GHz,
8.92GHz
-14.55db,-
16.64db
98MHz,
217MHz
-15.08db,-
18.77db,
-36.57db.
2.43GHz,
3.82GHz,
4.64GHz,
6.27GHz,
7.17GHz,
9.16GHz,
9.54GHz.
77MHz,
78MHz,
68MHz,
77MHz,
112MHz,
112 MHz
Optimized
Design
2.33GHz,7.60G
Hz,.8.53GHz
102MHz,
130MHz,
127MHz
Conventi
onal
Design
1.00 2.00 3.00 4.00 5.00 6.00 7.00 8.00 9.00 10.00
Freq [GHz]
-37.50
-25.00
-12.50
0.00
dB(S(p1,p1))
Curve Info
dB(S(p1,p1))
Setup1 : Sw eep
ls='34.874mm'
dB(S(p1,p1))
Setup1 : Sw eep
ls='34.874mm'
dB(S(p1,p1))
Setup1 : Sw eep
ls='34.874mm'
dB(S(p1,p1))
Setup1 : Sw eep
ls='34.874mm'
dB(S(p1,p1))
Setup1 : Sw eep
ls='34.874mm'
dB(S(p1,p1))
Setup1 : Sw eep
ls='34.874mm'
dB(S(p1,p1))
Setup1 : Sw eep
ls='34.874mm'
dB(S(p1,p1))
Setup1 : Sw eep
ls='34.874mm'
1.00 2.00 3.00 4.00 5.00 6.00 7.00 8.00 9.00 10.00
Freq [GHz]
-37.50
-25.00
-12.50
0.00
dB(S(p1,p1))
m1
m2
m3
m4m5 m6m7 m8m9
Curve Info
dB(S(p1,p1))
Setup1 : Sw eep
ls='34.874mm'
Name X Y
m1 2.3300 -15.0854
m2 7.6080 -18.7761
m3 8.5330 -36.5709
m4 2.2770 -10.0422
m5 2.3790 -10.0065
m6 7.5410 -9.8150
m7 7.6710 -9.9112
m8 8.4700 -10.0414
m9 8.5970 -10.1685
d(m4,m5) 0.1020 0.0357 0.3496 2.8604
d(m6,m7) 0.1300 -0.0962 -0.7399 -1.3515
d(m8,m9) 0.1270 -0.1271 -1.0006 -0.9994
-18.00
-17.00
-16.00
-15.00
90
60
30
0
-30
-60
-90
-120
-150
-180
150
120
HFSSDesign1Radiation Pattern 1 ANSOFT

__________________________________________________________________________________________
Now we have the results of both the conventional MSA as
well as the Optimized MSA with DGS & Circular Slot. These
results are presented in the table above
As we can easily analyze from the above table that the
proposed Microstrip Patch Antenna will work in the frequency
range of 2-8GHz. which covers the frequency of operation of
WLAN, WiMAX, and wireless communication through
satellite as well as the frequency of operation of RADAR-
that’s why it is multipurpose microstrip patch antenna.
REFERENCES
[1] David Sinchez-Hemindez and Ian D. Robertson, “Analysis
and Design of a Dual-Band Circularly Polarized Microstrip
Patch Antenna” IEEE Transactions on Antennas and
Propagation, issue 43, No2, February, 1995.
[2] Ramesh Garg, Prakash Bhatia.et.al ―Microstrip Antenna
Design Handbook‖ Artech House antennas a propagation
library, London, ISBN-0-89006-513-6, 2001.
[3] Constantine A. Balanis- Antenna Theory Analysis and
Design, Second Edition, John Wiley & Sons (Asia) Pte Ltd.
ISBN 9971-51-233-5,2001
[4] S. Bhunia, M.-K. Pain, S. Biswas, D. Sarkar, P. P. Sarkar,
and B. Gupta, “Investigations on Microstrip Patch Antennas
with Different slots and Feeding Points” , Microwave and
Optical Technology Letters, VOL 50, NO. 11, November
2008 pp 2754-2758.
[5] D. N. Elsheakh, H. A. Elsadek, and E. A. Abdallah
"Reconfigurable Single and Multi Band Inset Feed
Microstrip Patch Antenna for Wireless Communication
Devices" Progress In Electromagnetics Research C, Vol. 12,
191{201, 2010}.
[6] H. W. Liu, Z. F. Li and X. W. Sun, “A Novel Fractal
Defected Ground Structure for Microstrip Line,” Journal of
Active and Passive Electronic Devices, Vol. 1, 2006,pp.
311-316.
[7] C. S. Kim, J. S. Park, D. Ahn and J. B. Lim, “An Improved
1-D Periodic Defected Ground Structure for Microstrip
Line,” IEEE Microwave and Wireless Components Letters,
Vol. 10, No. 4, 2004, pp. 180-182.
[8] Z. Li and Y. Rahmat-Samii, “PBG, PMC, and PEC
Ground Planes: A Case Study of Dipole Antennas,” IEEE
Antennas and Propagation Society International
Symposium, Vol. 2, 2000, pp. 674-677.
[9] I.J. Bahl and P. Bhartia, Microstrip antennas, Artech House,
1980.
[10] G. Kumar and K. P. Ray, Broadband Microstrip
Antennas, First Edition, USA, Artech House, 2003.
[11] T.Huynh , K. F. Lee, “Single-Layer Single Patch Wideband
Microstrip Antenna,” Electronics Letters, vol. 31, no. 16,
August 1995, pp. 1310-1312.
[12] R. Chair, K. F. Lee, C. L. Mak, K. M. Luk and A. A.
Kishk,“Miniature Wideband Half U-Slot And Half E Patch
Antennas,”IEEE Transactions on Antenna And
Propagations, vol. 52, no. 8,August 2005, pp. 2645-2652.
[13] Barun Mazumdar, Ujjal Chakraborty, Aritra bhowmik,
S.K.Chowdhury, 2012 “Design of Compact Printed
Antenna for WiMAX & WLAN Applications”, Elsevier
Ltd., pp 87 – 91.
BIOGRAPHIES
Vandana Chopra, she is M.Tech (ECE)
student at Doaba Institute of Engineering
& technology, Mohali. She has earlier
completed her B.Tech in ECE from HEC,
Haryana. Her area of interest are Antenna
& Wave Propagation, Antenna designing
and fabrication, Signal Processing, and
optical fibre communication.
Email id: vandana_yng@yahoo.com
Maninder Kaur She is M.Tech by
Qualification and currently working as
Assistant Professor cum Coordinator at
Doaba Institute of Engineering and
Technology. Her area of interest is Image
Processing, optical Communication and
Wireless Communication. She has
published nine Papers in International Journals. She has
attended four national conferences and five International
Conferences. Email id: maninderecediet@gmail.com
Dr. K V P Singh, he is working as
Director Principal at Doaba Institute of
Engineering and Technology. Dr. Singh
is B.Tech, M.Tech, PHD, and PDF
Qualified. He has attended many
international and National conferences
and have Published Paper in national and
International Journals.
Sumit Kumar Jha, He has received
B.Tech degree in ECE from Kurukshetra
University, at SDDIET, Panchkula and
M.Tech degree from Kurukshetra
University, at ACE & AR Ambala. He is
currently guiding a number of students in
their thesis/dissertation and also has
published his research paper in
International Journal. His research interests are Wireless and
Mobile Communication, Microstrip antennas, Wave
propagation, Signal Processing, Wind Energy Conversion
Systems. Email id: skjha.indian@gmail.com

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