1. International Journal of Electronics and Communication Engineering & Technology (IJECET),
International Journal of Electronics and Communication
Engineering & Technology 0976 – 6472(Online) Volume 1, Number 1, Sep - Oct (2010), © IAEME
ISSN 0976 – 6464(Print), ISSN
(IJECET) IJECET
ISSN 0976 – 6464(Print), ISSN 0976 – 6472(Online)
Volume 1, Number 1, Sep - Oct (2010), pp. 99-106 ©IAEME
© IAEME, http://www.iaeme.com/ijecet.html
COMPLEMENTARY-SYMMETRIC CORNER
TRUNCATED COMPACT SQUARE MICROSTRIP
ANTENNA FOR WIDE BAND OPERATION
Kishan Singh
Department of PG Studies and Research in Applied Electronics
Gulbarga University
Gulbarga, E-Mail: kishanskrish@gmail.com
Shivasharanappa N Mulgi
Department of PG Studies and Research in Applied Electronics
Gulbarga University
Gulbarga, E-Mail: s.mulgi@rediffmail.com
ABSTRACT
A novel design of complementary-symmetry V-slot corner truncated square
microstrip antenna is designed for dual band operation with a gain of 8.51 dB. When arm
of V-slot is extended, the antenna resonates for triple band of frequencies. Further, by
adding one more arm to extended V-slot in the form of W. The triple bands are merged
into a single band and antenna gives maximum 85.37% of bandwidth and maximum gain
of 10.38 dB without affecting the nature of broad side radiation characteristics.
Truncating the corners of square patch makes the antenna compact in its size as that of
conventional square microstrip patch antenna. Details of the antenna design are presented
and experimental results are discussed. The proposed antennas may find the application
for the microwave communication systems operating from 6 to 18 GHz of frequencies.
Keywords: complementary-symmetry, wide band, gain, truncating, compact.
1. INTRODUCTION
In the recent communication era, the microstrip antennas have become one of the
most dynamic fields of antenna theory. The advantages of microstrip antennas include
small size, lightweight, low cost, easy to fabricate and low profile [1-3]. However, its
bandwidth is limited to a few percentages, which is one of the major drawbacks. In fact,
one of the popular techniques used for the enhancement of bandwidth is truncating the
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2. International Journal of Electronics and Communication Engineering & Technology (IJECET),
ISSN 0976 – 6464(Print), ISSN 0976 – 6472(Online) Volume 1, Number 1, Sep - Oct (2010), © IAEME
corners of radiating patch [4-5]. This technique also reduces the size of the patch and
makes the antenna compact. The compact antennas are more useful for the portable
microwave communication equipment such as global positioning satellite (GPS)
receivers. Further, the compact, dual or triple band microstrip antennas are more
attractive in recent microwave communication systems. When system requires operating
at two or more distinct band of frequencies, dual or triple band frequency patch antennas
may avoid the use of separate antennas for each operating band. Particularly these
antennas are attractive for many military and commercial applications where it is
desirable to have a single antenna that can be dynamically reconfigured to transmit and/or
receive on multiple frequency bands. The dual and triple band microwave antennas are
realized by many methods [6-9]. But in this paper a simple concept has been used in
designing complementary-symmetry V-slot corner truncated square microstrip antenna to
achieve dual and triple band operation. Further by controlling the arm of V-slot, the triple
bands are merged into a single band and antenna gives highest bandwidth and gain.
2. DESIGNING OF ANTENNA GEOMETRY
The artwork of proposed antennas is designed by using the equations available for
the design of square microstrip antenna [10, 1] and is sketched using computer software
Auto CAD–2006 to achieve better accuracy. The antennas are fabricated using
photolithography process on low cost glass epoxy substrate material of thickness h = 3.2
mm and dielectric constant εr = 4.2.
Figure 1 Geometry of VCCSMA
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3. International Journal of Electronics and Communication Engineering & Technology (IJECET),
ISSN 0976 – 6464(Print), ISSN 0976 – 6472(Online) Volume 1, Number 1, Sep - Oct (2010), © IAEME
Figure 1 shows the geometry of V-slot complementary-symmetry corner
truncated square microstrip antenna (VCCSMA). The VCCSMA is derived from square
microstrip antenna, which is designed for the resonant frequency of 9.4 GHz. The length
and width of the complementary-symmetry square patch are L and W respectively. The
corners of square patch is truncated by Ls= Ws= 2 mm. The VCCSMA structure is
complementary- symmetry along its center axis. The complementary V-slots are having
an angle of 240 between the arms. The V-slots are placed at one end of the non-radiating
edges along the length of VCCSMA. The dimensions of V-slot are taken in terms of λo,
where λo is the free space wavelength in cm corresponding to the designed frequency of
9.4GHz. The length and width of V-slot or complementary V-slot are taken as VL and Vw
respectively. The antenna is fed by using microstripline feeding. This feeding has been
selected because it is simple in design and can be simultaneously fabricated along with
the antenna element. The feed arrangement consist of quarter wave matching transformer
of length Lt and width Wt which is connected between microstripline feed of length Lf
and width Wf. At the tip of microstripline feed a 50Ω co-axial SMA connector is used for
feeding the microwave power.
Figure 2 Geometry of ECCSMA Figure 3 Geometry of WCCSMA
Figure 2 shows the geometry of extended V-slot complementary-symmetry corner
truncated square microstrip antenna (ECCSMA). In this figure one more arm is added to
V-slot of VCCSMA. The feed arrangement of this antenna remains same as that of Figure
1. Further an arm of V-slot of ECCSMA is extended. The extended slot appears in the
form of W. This antenna is named as W-slot complementary-symmetry corner truncated
square microstrip antenna (WCCSMA) as shown in Figure 3. The feed arrangement of
this antenna remains same as that of Figure 1. Table 1 shows the list of designed
parameters of the proposed antennas.
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4. International Journal of Electronics and Communication Engineering & Technology (IJECET),
ISSN 0976 – 6464(Print), ISSN 0976 – 6472(Online) Volume 1, Number 1, Sep - Oct (2010), © IAEME
Table 1 Design Parameters of Proposed Antennas
Antenna Dimension in
Parameters mm
h 3.2
L 7.6
W 7.6
Wt 1.0
Lt 4.1
Wf 6.3
Lf 4.0
WS 2.0
LS 2.0
VL 2.0
VW 0.25
3. EXPERIMENTAL RESULTS
Figure 4 Variation of return loss versus frequency of VCCSMA
The bandwidth over return loss less than −10 dB for the proposed antennas is
measured on Vector Network Analyzer (Rohde & Schwarz, Germany make ZVK model
1127.8651). The variation of return loss versus frequency of VCCSMA is as shown in
Figure 4. From this figure it is seen that, the VCCSMA resonates for two bands of
frequencies BW1 and BW2. The magnitude of each operating band is found to be 11.16%
and 36.01% respectively which is determined by the equation,
 (f − f ) 
Bandwidth =  2 1  ×100 % (1)
 fc 
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5. International Journal of Electronics and Communication Engineering & Technology (IJECET),
ISSN 0976 – 6464(Print), ISSN 0976 – 6472(Online) Volume 1, Number 1, Sep - Oct (2010), © IAEME
Figure 5 Variation of return loss versus frequency of ECCSMA
Where, f1 and f2 are the lower and upper cut-off frequencies of the band respectively
when its return loss becomes −10 dB and fc is the center frequency between f1 and f2. The
obtained dual bands are due to the fundamental resonance of the patch and combined
effect of complementary V-slots as they resonate near to the patch resonance [11]. When
arm of V-slot is extended i.e. ECCSMA, the antenna resonates for triple band of
frequencies BW3, BW4 and BW5 with a magnitude of 11.30%, 42.51% and 8.70%
respectively. The variation of return loss versus frequency of this antenna is as shown in
Figure 5. From this figure it is clear that the bandwidth BW3 remains closely same as that
of BW1 as shown in Figure 4, but BW4 increases to 42.51% which is 18.02% more when
compared to BW2 as shown in Figure 5. The appearance of BW5 is due to extension of V-
slot, which resonates independently in ECCSMA [12].
Figure 6 Variation of return loss versus frequency of WCCSMA
The variation of return loss versus frequency of WCCSMA is as shown in Figure
6. From this figure it is seen that the antenna resonates for single band of frequency BW6
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6. International Journal of Electronics and Communication Engineering & Technology (IJECET),
ISSN 0976 – 6464(Print), ISSN 0976 – 6472(Online) Volume 1, Number 1, Sep - Oct (2010), © IAEME
and gives maximum 85.37% of bandwidth. The merging of all three bands BW3, BW4 and
BW5 as shown in Figure 5 into BW6 in WCCSMA is due to combined resonance effect of
radiating element and slots that resonates very close to the patch resonance [12]. The slot
can be either resonant or non-resonant if it is resonant the current along the edges of the
slot introduces an additional resonance, which adds to the fundamental resonance of
radiating element, causing merging of nearby bands and hence enhancement in the
bandwidth [11, 13] which is evident from Figure 6.
The gain of the proposed antennas is measured by absolute gain method. The
power transmitted ‘Pt’ by pyramidal horn antenna and power received ‘Pr’ by antenna
under test (AUT) are measured independently. With the help of these experimental data,
the gain (G) dB of AUT is calculated by using,
P   λ 
(G) dB=10 log  r  - (G t ) dB - 20log  0  dB (2)
 Pt   4πR 
Where, Gt is the gain of the pyramidal horn antenna and R is the distance between the
transmitting antenna and the AUT. Using equation (2), the maximum gain of the
proposed antennas measured in their operating bands BW1, BW4 and BW6 are found to be
8.51 dB, 9.25 dB and 10.38 dB respectively. Hence it is clear that WCCSMA gives
highest gain when compared to VCCSMA and ECCSMA.
Figure 7 Radiation Pattern of VCCSMA measured at 8.53 GHz
Figure 7-9 shows the typical co-polar and cross-polar radiation pattern of
VCCSMA, ECCSMA and WCCSMA respectively measured at their operating bands.
From these figures it is clear that, the patterns are broadsided and linearly polarized.
Hence it is seen that the WCCSMA show the nature of radiation pattern same as that of
VCCSMA and ECCSMA in spite of enhancement in the impedance bandwidth and gain.
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7. International Journal of Electronics and Communication Engineering & Technology (IJECET),
ISSN 0976 – 6464(Print), ISSN 0976 – 6472(Online) Volume 1, Number 1, Sep - Oct (2010), © IAEME
Figure 8 Radiation Pattern of ECCSMA measured at 13.07 GHz
Figure 9 Radiation Pattern of WCCSMA measured at 12 GHz
4. CONCLUSION
From the detailed experimental study, it is concluded that, the dual band operation
obtained from VCCSMA can be converted into triple bands by extending the arm of V-
slot. Further, extending V-slot in the form of W-slot i.e. WCCSMA, the triple band
operation is converted into single band and antenna gives maximum 85.37 % of
bandwidth and 10.38 dB of gain without changing the nature of radiation characteristics.
The proposed antennas are simple in their design and fabrication and they use low cost
glass substrate material. These antennas may find the application in the microwave
communication systems operating from 6 to 18 GHz of frequencies.
ACKNOWLEDGEMENTS
The authors would like to thank the authorities of Dept. of Sci. & Tech. (DST),
Govt. of India, New Delhi, for sanctioning the Network Analyzer under the FIST project
to the Department of Applied Electronics, Gulbarga University, Gulbarga.
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8. International Journal of Electronics and Communication Engineering & Technology (IJECET),
ISSN 0976 – 6464(Print), ISSN 0976 – 6472(Online) Volume 1, Number 1, Sep - Oct (2010), © IAEME
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