1. International Journal of Advanced Research in Engineering and Technology (IJARET), ISSN 0976 –
6480(Print), ISSN 0976 – 6499(Online) Volume 5, Issue 2, February (2014), pp. 163-167, © IAEME
163
BACK FED TOP GROUND EQUILATERAL TRIANGULAR
MICROSTRIP ANTENNA FOR QUAD BAND OPERATION
Dr. Nagraj K. Kulkarni
Government College, Gulbarga-585105, Karkataka, India
ABSTRACT
This paper presents the design and development back fed top ground equilateral triangular
microstrip antenna for quad band operation. The antenna is constructed with a volume of dimension
8 X 5 X 0.16 cm3
and operates between 1.68 to 10.32 GHz. The antenna gives a maximum
impedance bandwidth of 28.6% with a peak gain of 3.26 dB. The microstripline feed arrangement is
used to supply the microwave power to the antenna. The low cost glass epoxy substrate material is
used to fabricate the antenna. The antenna shows broadside and linearly polarized radiation
characteristic. The design detail of the antenna is described. The experimental results are presented
and discussed. This antenna may find applications in DCS1900, WLAN and for systems operating in
X-band of frequencies.
Key words: Triangular Microstrip Antenna, Back Fed, Quad Band, U-Slot, Slits.
1. INTRODUCTION
In modern communication era the microstrip antennas have become attractive candidates that
act as good aids for transmit/receive purpose in emerging communication applications such as
WLAN, WiMax and 4G mobile systems, because of their numerous inherent advantages like low
fabrication cost, planar configuration integrability with MMICs and ease of installation [1]. But an
antenna operating at single, dual and triple band is more attractive to use the device for the desired
set of frequency bands. The antenna designers put forth much efforts to realize triple and multiple
band antennas by many methods such as, slot on the patch, arrays [2-4] etc. But in this study a simple
back feed and top ground technique is used to excite equilateral triangular microstrip antenna having
U shaped slot and slits to achieve quad band operation. This kind of antenna is found to be rare in the
literature.
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ISSN 0976 - 6480 (Print)
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Volume 5, Issue 2, February (2014), pp. 163-167
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2. International Journal of Advanced Research in Engineering and Technology (IJARET), ISSN 0976 –
6480(Print), ISSN 0976 – 6499(Online) Volume 5, Issue 2, February (2014), pp. 163-167, © IAEME
164
2. ANTENNA DESIGN
The conventional equilateral triangular microstrip antenna (CETMSA) and the U slot, slit
loaded back fed equilateral triangular microstrip antenna (USBFETMSA) are fabricated on low cost
glass epoxy substrate material of thickness h = 0.16 cm and εr = 4.2. The art work of proposed
antennas is sketched using auto-CAD software to achieve better accuracy. The antennas are etched
using the photolithography process.
Figure 1: Top view geometry of CETMSA
Figure 1 shows the top view geometry of CETMSA. The radiating patch of side S is designed
for the resonant frequency of 3.5 GHz, using the basic equations available in the literature [1]. A
quarter wave transformer of length Lt and width Wt is used between CP along the width of the patch
and microstripline feed of length Lfeed and width Wfeed for matching their impedances. A semi
miniature-A (SMA) connector of 50 impedance is used at the tip of the microstripline to feed the
microwave power.
Figure 2: Top and bottom view geometry of USBFETMSA.
Figure 2 shows the top and bottom view geometry of USBFETMSA. The two slits of lengths
L1 and L2 each of width 1 mm are placed on either side of the equilateral triangular radiating patch
taking the middle perpendicular as reference. The U shaped slot of width 1 mm having horizontal
and vertical arm lengths h and v is placed at the center of the patch. The ground plane of horizontal
and vertical length P and Q is placed on the top side of the substrate. The dimensions L1 L2, h, v, P
and Q are taken in terms of λ0, where λ0 is a free space wave length in cm corresponding to the
designed frequency of 3.5 GHz. Table 1 shows the design parameters of CETMSA and
USBFETMSA.

3. International Journal of Advanced Research in Engineering and Technology (IJARET), ISSN 0976
6480(Print), ISSN 0976 – 6499(Online) Volume 5, Issue 2, February (2014), pp.
Table 1: Design parameters of CETMSA and
Antenna S Lf
CETMSA 2.82 4.19
USBFETMSA 2.82 4.19
3. RESULTS AND DISCUSSION
Vector Network Analyzer (The
experimental return loss of CETMSA and
Figure 3 shows the variation of re
is seen that, the CETMSA resonates at 3.3
frequency of 3.5 GHz. The experimental bandwidth is calculated using the formula,
Bandwidth (%) =
where, f2 and f1 are the upper and lower cut off frequencies of the resonated band when its
return loss reaches -10dB and fc is a centre frequency between f
is found to be 1.8 %.
Figure 3: Variation of return loss versus frequency of
Figure 4: Variation of return loss versus frequency of
Figure 4 shows the variation of return loss versus frequency of
this figure that, the antenna operates for
International Journal of Advanced Research in Engineering and Technology (IJARET), ISSN 0976
6499(Online) Volume 5, Issue 2, February (2014), pp. 163-167
165
Design parameters of CETMSA and USBFETMSA
Wf P Q L1 L2
4.19 0.31 - - - -
4.19 0.31 λ0/1.7 λ0/4 λ0/7.9 λ0/13.6 λ
Vector Network Analyzer (The Agilent N5230A: A.06.04.32) is used to measure the
of CETMSA and USBFETMSA.
shows the variation of return loss versus frequency of CETMSA. From this figure it
MSA resonates at 3.30 GHz of frequency which is close to the designed
frequency of 3.5 GHz. The experimental bandwidth is calculated using the formula,
2 1
c
f f
Bandwidth (%) =
f
−
× 100
are the upper and lower cut off frequencies of the resonated band when its
is a centre frequency between f1 and f2. The bandwidth of
Variation of return loss versus frequency of CETMSA
Variation of return loss versus frequency of USBFETMSA
shows the variation of return loss versus frequency of USBFETMSA
this figure that, the antenna operates for four bands BW1 = 20.8 % (1.68-2.07 GHz), BW
International Journal of Advanced Research in Engineering and Technology (IJARET), ISSN 0976 –
7, © IAEME
USBFETMSA.
h v
- -
λ0/2 λ0/6
is used to measure the
MSA. From this figure it
GHz of frequency which is close to the designed
are the upper and lower cut off frequencies of the resonated band when its
The bandwidth of CETMSA
USBFETMSA
USBFETMSA. It is clear from
GHz), BW2 = 3.07%

4. International Journal of Advanced Research in Engineering and Technology (IJARET), ISSN 0976 –
6480(Print), ISSN 0976 – 6499(Online) Volume 5, Issue 2, February (2014), pp. 163-167, © IAEME
166
(4.81- 4.96 GHz), BW3 = 3.52% (5.58-5.78 GHz) and BW4 = 28.6 % (7.74-10.32 GHz) for the
resonating modes of f1, f2 f3 and f4 respectively. The BW1 is due to the fundamental resonance of the
patch. The bands BW2 to BW4 are due to the U- slot and the slits present on the patch. Further it can
be noted that the insertion of the top ground gives the virtual size reduction of about 51 %. Hence
this antenna can be considered as compact antenna.
Figure 5: Radiation pattern of CETMSA measured at 3.30 GHz
Figure 6: Radiation pattern of USBFETMSA measured at 4.885 GHz
Figure 5 and 6 show the far field co-polar and cross-polar radiation patterns of CETMSA and
USBFETMSA measured in their operating bands. From these figures it is observed that, the patterns
are broadsided and linearly polarized. The gain of the proposed antenna is calculated using absolute
gain method given by the relation,
( ) 0r
t
λPG (dB) = 10 log - (Gt) dB - 20 log dB
P 4πR
 
 
 
where, Pt and Pr are transmitted and received powers respectively. R is the distance
between transmitting antenna and antenna under test. The peak gain of USBFETMSA measured in
BW1 is found to be 3.26 dB with a half power beam width of 540
.
4. CONCLUSION
From this detailed study it is concluded that, USBFETMSA gives four bands with a
maximum bandwidth of about 28.6 % in BW4. The USBFETMSA operates between 1.68 to 10.32
GHz. The antenna gives a virtual size reduction of 51% and exhibits broadside radiation
characteristics with a peak gain of 3.26 dB. The proposed antenna uses low cost substrate material
with simple design and fabrication. This antenna may find applications in DCS1900, WLAN and for
systems operating in X-band of frequencies.

5. International Journal of Advanced Research in Engineering and Technology (IJARET), ISSN 0976
6480(Print), ISSN 0976 – 6499(Online) Volume 5, Issue 2, February (2014), pp.
REFERENCES
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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.
International Journal of Advanced Research in Engineering and Technology (IJARET), ISSN 0976
6499(Online) Volume 5, Issue 2, February (2014), pp. 163-167
167
Microstrip Antennas”, Artech house, New Delhi, 1980
Girish Kumar and K. P. Ray, “Broadband microstrip Antennas”, Artech House, Boston,
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Journal of Electronics and Communication Engineering & Technology (IJECET), Volume 4,
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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 Department of
Electronics Government Degree College Gulbarga. He is an active researcher
field of Microwave Electronics.
International Journal of Advanced Research in Engineering and Technology (IJARET), ISSN 0976 –
7, © IAEME
, Artech house, New Delhi, 1980.
Antennas”, Artech House, Boston,
Analysis and Modeling
ACMPA with Asymmetric Crossed Slots”, Microwave and Opt. Technol. Lett.
Wiley, New York,
Archana Agarwal, Manish Kumar, Priyanka Jain and Shagun Maheshwari, “Tapered Circular
Microstrip Antenna with Modified Ground Plane for UWB Communications”, International
Journal of Electronics and Communication Engineering & Technology (IJECET), Volume 4,
Development of
”, International Journal of
Electronics and Communication Engineering & Technology (IJECET), Volume 4, Issue 3,
degree in Applied
ty Gulbarga in the year 1995, 1996 and 2014
in the Department of
active researcher in the