40120140503002

International Journal of Electronics and Communication Engineering & Technology (IJECET), ISSN 0976 –
6464(Print), ISSN 0976 – 6472(Online), Volume 5, Issue 3, March (2014), pp. 08-12 © IAEME
8
DUAL OPEN STUB LOADED SQUARE MICROSTRIP ANTENNA FOR
WLAN AND WIMAX APPLICATIONS
Dr. Nagraj Kulkarni
Government College, Gulbarga-585105, Karkataka, India
ABSTRACT
In this communication the square microstrip antenna consisting of dual open stubs is
presented for quad band operation. The antenna operates between 2.88 to 8.55 GHz. The antenna is
constructed with its structure of dimension 8 X 5 X 0.16 cm3
. The microstripline feed arrangement
along with quarter wave transformer is used to excite the antenna. The antenna exhibits a broadside
and linear radiation characteristics. The peak gain of 3.21 dB is obtained in the operating band. The
results are presented and discussed. This antenna may find its applications in WLAN and Wimax
communication system.
Key words: Square, gain, microstrip antenna.
1. INTRODUCTION
The microstrip antennas (MSAs) have gained popular position in today’s communication
system because of their inherent attractive features like light weight, planar in structure, ruggedness,
different geometries and shapes, easy installation, low fabrication cost [1] etc. It is the need of the
hour to select the antenna that uses single antenna for transmit/receive purpose. The microstrip
antenna designers worked hard to put forth many methods and techniques such as cutting slots of
different geometries like triangular, bow-tie, rectangular narrow slot, square, circular ring etc. on the
radiating patch [2-7], use of corner truncated patches, implementing stubs and shorts on the patches
[8-10] etc. to achieve dual, triple and multiband operations. But the antenna operating at four
independent bands is presented with simple stub loading technique. This kind of study is found to be
rare in the literature.
2. DESIGNING
The low cost glass epoxy substrate material of area A × B, thickness h = 0.16 cm and
dielectric constant εr = 4.2 is used to fabricate the proposed antenna. The artwork of the antenna is
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ISSN 0976 – 6464(Print)
ISSN 0976 – 6472(Online)
Volume 5, Issue 3, March (2014), pp. 08-12
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6464(Print), ISSN 0976 – 6472(Online), Volume 5, Issue 3, March (2014), pp. 08-12 © IAEME
9
sketched using computer software Auto CAD to achieve better accuracy. Photolithography process is
used to fabricate the antenna.
Figure 1: Top view geometry SMSA
Figure 1 shows the top view geometry of square microstrip antenna (SMSA), which is
designed for the resonant frequency of 3.5 GHz using the equations available in the literature for the
design of square microstrip antenna [11]. The SMSA consists of a square radiating patch of equal
length (L) and width (W). The Lf and Wf are the length and width of the microstripline used to
excite the patch. A semi miniature-A (SMA) connector of 50 impedance is used at the tip of the
microstripline to feed the microwave power. A quarter wave transformer of length Lt and width Wt
is used to match the impedances between lower radiating edge of the patch and microstripline feed.
Figure 2: Geometry of DOSMSA
Figure 2 shows the geometry of dual open stub loaded square microstrip antenna (DOSMSA).
Two open stubs of horizontal and vertical lengths X and Y respectively are placed at two diagonally
opposite corners of the SMSA. Table 1 gives the design parameters of SMSA and DOSMSA.
Table 1: Design parameters of SMSA and DOSMSA ( cm )
Antenna L W Lf Wf Lt Wt A B X Y
SMSA 2.04 2.04 2.18 0.32 1.09 0.06 5 8 - -
DOSMSA 2.04 2.04 2.18 0.32 1.09 0.06 5 8 0.8 0.2
3. EXPERIMENTAL RESULTS
The Agilent Technologies make (Agilent N5230A: A.06.04.32), Vector Network Analyzer
is used to measure the experimental return loss of SMSA and DOSMSA.

International Journal of Electronics and Communication Engineering & Technology (IJECET), ISSN 0976
6464(Print), ISSN 0976 – 6472(Online), Volume 5, Issue
Figure 3: Variation of retur
Figure 3 shows the variation of return lo
seen that, the SMSA resonates at 3.43
of 3.5 GHz. The experimental impe
using the formula,
Impedance bandwidth (%) =
where, fH and fL are the upper and lower cut off frequencies of the resonating bands
when their return loss reaches -10 dB and f
bandwidth is found to be 2.94 %.
Figure 4: Variation of return loss versus freque
Figure 4 shows the variation of return loss versus frequency of
resonates at four modes of frequencies f
BW1 = 5.7 % (2.88-3.05 GHz) BW2 =
= 19.65 % (7.02-8.55 GHz). The first band BW
the bands BW2 to BW4 are due to insertion
that, the use of stubs on the patch, the frequency ratio between the successive bands is nearly
The copper area of DOSMSA reduces
6472(Online), Volume 5, Issue 3, March (2014), pp. 08-12 © IAEME
10
Variation of return loss versus frequency of SMSA
shows the variation of return loss versus frequency of SMSA. From this figure it is
the SMSA resonates at 3.43 GHz of frequency which is nearer to the designed
of 3.5 GHz. The experimental impedance bandwidth over return loss less than -10 dB is calculated
Impedance bandwidth (%) =
H L
C
f f
f
−
× 100 % (1)
are the upper and lower cut off frequencies of the resonating bands
10 dB and fC is a centre frequency of fH and fL.
Variation of return loss versus frequency of SMSA
shows the variation of return loss versus frequency of DOSMSA
resonates at four modes of frequencies f1, f2, f3 and f4 with their respective impedance bandwidths are
= 6.1 % (4.71-5.01 GHz) BW3 = 3.2 % (6.60-6.82
The first band BW1 is due to the fundamental resonance of the patch and
due to insertion of open stubs on the radiating patch. Further it is noted
the frequency ratio between the successive bands is nearly
reduces by 7.8 % when compared to the copper area of S
© IAEME
. From this figure it is
which is nearer to the designed frequency
10 dB is calculated
are the upper and lower cut off frequencies of the resonating bands
L. The impedance
DOSMSA. The antenna
with their respective impedance bandwidths are
6.82 GHz) and BW4
is due to the fundamental resonance of the patch and
patch. Further it is noted
the frequency ratio between the successive bands is nearly 1.63.
ompared to the copper area of SMSA.

Figure 5: Radiation pattern of
Figure 6: Radiation pattern of
Fig 5 and 6 show the radiation patterns of
from these figures that, the patterns are broadside and linearly polarized. The cross
is much lower when compared to the co
The gain of SMSA and DOSMSA is calculated using the absolute gain method given by t
( ) 10 log - ( ) - 20logG dB G dB dB=
where, Gt is the gain of the pyramidal horn antenna and R is the distance between the
transmitting antenna and the antenna under test (AUT). The power received by AUT, ‘P
power transmitted by standard pyramidal horn antenna ‘P
measured for SMSA is found to be 0.8
3.21 dB. This indicates that the novel geometry of
times in its operating band when compared to the gain of
4. CONCLUSION
From this detailed study, it is concluded that
3.21 dB which is nearly 4 times more when compared to the gain of
stubs on the two diagonally opposite corners
independent bands between 2.88 to
The placement of stubs also makes the antenna to use less copper area of about
compared to the copper area of SMSA. The radiation characteristics of
broadside and linearly polarized. The proposed antenna is simple in its geometry an
This antenna may be used for WLAN
11
Radiation pattern of SMSA measured at 3.43 GHz
Radiation pattern of DOSMSA measured at 2.965 GHz
the radiation patterns of SMSA and DOSMSA respectively.
patterns are broadside and linearly polarized. The cross-polar power level
is much lower when compared to the co-polar power level indicates the broad nature of radiation.
SMSA is calculated using the absolute gain method given by t
0
( ) 10 log - ( ) - 20log
4
r
t
t
P
G dB G dB dB
P R
λ
π
   
  
  
(2)
is the gain of the pyramidal horn antenna and R is the distance between the
transmitting antenna and the antenna under test (AUT). The power received by AUT, ‘P
power transmitted by standard pyramidal horn antenna ‘Pt’ is measured independently.
is found to be 0.8 dB maximum and the peak gain of DOSMSA
dB. This indicates that the novel geometry of DOSMSA enhances the gain of the antenna
band when compared to the gain of SMSA.
From this detailed study, it is concluded that DOSMSA enhances the gain from
more when compared to the gain of SMSA. The use of dual open
stubs on the two diagonally opposite corners of DOSMSA make antenna to operate for
8.55 GHz with a frequency ratio nearly 1.63 between the bands.
also makes the antenna to use less copper area of about
MSA. The radiation characteristics of SMSA and
broadside and linearly polarized. The proposed antenna is simple in its geometry an
WLAN and Wimax communication system.
© IAEME
SMSA respectively. It can be noted
polar power level
polar power level indicates the broad nature of radiation.
SMSA is calculated using the absolute gain method given by the relation,
is the gain of the pyramidal horn antenna and R is the distance between the
transmitting antenna and the antenna under test (AUT). The power received by AUT, ‘Pr’ and the
measured independently. The gain
DOSMSA is found to be
enhances the gain of the antenna by 4
the gain from 0.8 dB to
The use of dual open
antenna to operate for four
between the bands.
also makes the antenna to use less copper area of about 7.8 % when
MSA and DOSMSA are
broadside and linearly polarized. The proposed antenna is simple in its geometry and construction.

REFERENCES
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Engineering & Technology (IJECET), Volume
0976- 6464, ISSN Online: 0976
BIO-DATA
Dr. Nagraj K. Kulkarni
Electronics from Gulbarga Universi
respectively. He is working as an Assistant professor
Electronics Government Degree C
field of Microwave Electronics.
12
P. Ray, Broadband Microstrip Antennas, MA: Artech House, Norwood,
Elsherbeni, and C.E. Smith, “Characteristics of bow-tie slot antenna
stubs for wideband operation,” Progress In Electromagnetic Research
Daniel C. Nascimento, Ricardo Schildberg, and J. C. da S. Lacava, “Design of Low
Microstrip Antennas for Glonass Applications”, PIERS, vOL. 4, NO. 7, (2008),
F. Geran, and G. Dadashzadeh, “A compact microstrip
applications,” Progress In Electromagnetic Research PIER 67, (2007),
K.P.Ray. and Deepti Das Krishna, “Compact dual band suspended semicircular
Microwave and Optical Technology Letters, Vol.48, Oct. (2006),
J. Nakasuwan, N. Songthanapitak N. Anantrasirichai and
“Design Narrow Slot Antenna for Dual Frequency”, PIERS, vol. 3, No. 7, (2007), 1024
M Youssef Omar, and Darwish Abdelaz, “Tri
Equilateral Triangular Microstrip Antenna for Compact and Dual-Frequency Operation”,
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tuning stub”, IEEE Trans. Ant and Propagat, 48(2000).
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: MacGraw Hill Pub Co.Ltd.
Chandrappa D.N., P.A.Ambresh and P.V.Hunagund, “Varactor Diode Loaded Double Square
Reconfigurable Microstrip Patch Antenna for Wireless Applications”, International
Electronics and Communication Engineering &Technology (IJECET), Volume
, ISSN Print: 0976- 6464, ISSN Online: 0976 –6472.
vasharanappa N Mulgi,, “Complementary-Symmetric Corner Truncated
Compact Square Microstrip Antenna for Wide Band Operation”, International
Electronics and Communication Engineering & Technology (IJECET), Volume
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Kulkarni received his M.Sc, M.Phil and Ph. D degree in Applied
Electronics from Gulbarga University Gulbarga in the year 1995,
respectively. He is working as an Assistant professor and Head, in the
Electronics Government Degree College Gulbarga. He is an active researcher
field of Microwave Electronics.
© IAEME
: Artech House, Norwood,
slot antenna with
Research PIER 49,
Design of Low-cost
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“A compact microstrip square-ring slot
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Vol.48, Oct. (2006),
T. Wakabayashi,
PIERS, vol. 3, No. 7, (2007), 1024-1028.
and Darwish Abdelaz, “Tri-Slot Loaded
Frequency Operation”,
adband stacked shorted patch” Electronic Lett, 35, (1999), 98-100.
equilateral triangular
(2000). 1869-1872,
profile Patch antenna
nd P.V.Hunagund, “Varactor Diode Loaded Double Square
International Journal of
g &Technology (IJECET), Volume 4, Issue 4,
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Technology (IJECET), Volume 1, Issue 1,
nd Archanaagarwal, “Enhanced Bandwidth Slotted
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- 47, ISSN Print:
degree in Applied
ty Gulbarga in the year 1995, 1996 and 2014
in the Department of
active researcher in the

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