Gain Enhancement of Series Feed Square Patch Microstrip Antenna Array for S band & C Band Applications

IJSRD - International Journal for Scientific Research & Development| Vol. 2, Issue 09, 2014 | ISSN (online): 2321-0613
All rights reserved by www.ijsrd.com 449
Gain Enhancement of Series Feed Square Patch Microstrip Antenna
Array for S band & C Band Applications
Ravikant Bharati1 Surendra Kumar Sriwas2
1,2
Dept. of Electronics & Communication Engineering
Bundelkhand Institute of Engineering & Technology, Jhansi, India
Abstract— Gain is the ability of an antenna to concentrate
the radiated power in a desired direction. Only small gain
can be achieved by single antenna that is why, antenna
arrays are required to improve the gain by using different
feed networks. This paper describes the design and
performance of a series feed antenna array. The operating
frequency of 2.4GHz is used. The aim of this paper is to
improve the gain of a series feed antenna array. Line feed is
used for designing single antenna, 2x1 & 4x1 microstrip
antenna array. These series feed microstrip antenna arrays
are useful for both S and C band. The proposed antenna is
simulated by IE3D version 9.0 Zealand simulation software
based on method of moments.
Keywords: patch antenna, enhance gain, Microstrip Patch
antenna array, microstrip line feed
I. INTRODUCTION
A microstrip patch antenna consists of a radiating patch on
one side and ground plane on the other with a dielectric
substrate between them. Microstrip patch antenna possesses
many advantages such as low profile, light weight, small
volume and compatibility with microwave integrated circuit
(MIC) and monolithic microwave integrated circuit (MMIC)
but the major drawback of microstrip antenna is its narrow
bandwidth and low gain. The use of Microstrip arrays is
limited in a way that they tend to radiate efficiently only
over a narrow band of frequencies and they cannot operate
at the high power levels of waveguide, coaxial line or even
stripline [1]. In various communication and radar systems
microstrip antenna can be very useful. Microstrip antennas
are very versatile and can be used amongst other things, to
synthesize a desired pattern that cannot be achieved with a
single element. In addition, they can also be used to scan the
beam of an antenna system, increase the directivity and
perform various other functions which would be difficult
with a single element. The elements can be feed by a single
line or by multiple lines in a feed network arrangement. The
first is referred as the series-feed network while the second
is referred as corporate-feed network [2]. Antenna arrays are
used to enhance the gain. This paper presents the
characteristic of microstrip antenna arrays, there
performance comparisons are also given for better
understanding. In the present work the gain of antenna is
increased upto 11.50 db by using the series feed
methods.The proposed antenna arrays are designed on glass
epoxy substrate (εr=4.4) [6].The substrate material has large
influence in determining the size and bandwidth of an
antenna. Increasing the dielectric constant decreases the size
but lowers the bandwidth and efficiency of antenna while
decreasing the dielectric constant increases the bandwidth
but with an increase in size. The design frequency of
proposed antenna is 2.4 GHz.
II. MICROSTRIP SERIES FEED ANTENNA ARRAY DESIGN
Microstrip antennas are used not only as single elements but
are very popular in arrays. The objective of the study of
antenna array is to increase the gain and directivity of
antenna. The greater the number of elements in an array, the
more is its directivity and consequently will have a greater
gain. The use of antenna arrays has been increased vastly in
telecommunications. If we reduce the width of the patch, the
radiation impedance is insufficient to match the input
impedance. We can use the microstrip patch as a
transmission line and connect a line opposite to the feed to
lead the other patches. If we space the patches by half
wavelength, the impedance of the patches will add in phase
at the input. The Characteristic impedance of the connecting
lines has no effect at center frequency. The junction of
transmission-line feeder and the patch introduces extra
phase shift. A major limitation in series-feed arrays is the
large variation of the impedance and beam-pointing
direction over a band of frequencies.
III. ANTENNA DESIGN
For designing a rectangular Microstrip patch antenna, the
length and width are calculated as below [4]
w=
𝑐
2𝑓𝑟
√
2
𝜀𝑟+1
(1)
Where c is the velocity of light, εr is the dielectric
constant of substrate, ƒr is the antenna design frequency, W
is the patch width, and the effective dielectric constant εreff is
given as [4]
εreff =
𝜀 𝑟+1
2
+
𝜀 𝑟−1
2
[1 + 12
ℎ
𝑊
]
−
1
2
(2)
At h=1.6mm
The extension length ΔL is calculated as [4]
∆𝐿
ℎ
= 0.412
(𝜀 𝑟𝑒𝑓𝑓+0.3)(
𝑊
ℎ
+.264)
(𝜀 𝑟𝑒𝑓𝑓−.258)(
𝑊
ℎ
+0.8)
(3)
By using the above mentioned equation we can find the
value of actual length of the patch as [4]
𝐿 =
𝑐
2𝑓𝑟
√𝜀𝑟𝑒𝑓𝑓
− 2∆𝐿 (4)
The length and the width of the ground plane can be
calculated a [4]
𝐿 𝑔=6h+L (5)
𝑊 𝑔=6h+𝑊 (6)

Gain Enhancement of Series Feed Square Patch Microstrip Antenna Array for S band & C Band Applications
(IJSRD/Vol. 2/Issue 09/2014/101)
A. Calculation for Square Patch
It is known that equal areas provide equal radiations. So by
equating the areas of rectangular and square patches we get
LxW=A2
Where L and W is the length and width of the
rectangle respectively and A is the side of square.
IV. ANTENNA DESIGN SPECIFICATIONS
The proposed antenna is designed by using glass epoxy
substrate which has a dielectric constant of 4.4 and the
design frequency 2.4 GHz. The dimensions of the
rectangular patch are 38.39 mm and 29.82 mm but for the
square patch it comes out to be 33.83 mm The ground
plane length and width are taken 43.83 mm and 43.83mm
respectively.. Length and width of feed network is
15mmx2mm respectively. Dimensions of the line feed are
8mmx4mm. Height of the dielectric substrate is 1.6mm and
loss tangent tan δ is .0013. Simulation work is done by using
IE3D simulation software. All the specifications are given in
the table1.
V. ANTENNA DESIGN PROCEDURE
All the dimensions of proposed antenna and antenna arrays
should be calculated very carefully by using the equations 1,
2, 3, 4, 5 and 6. Design frequency of 2.4 GHz is selected for
making the proposed microstrip antenna array. The
geometry of proposed antenna array is shown in fig 1, fig 4
& fig 9. Line feed is used to achieve the maximum gain
while designing the proposed antenna array on IE3D.
S. No. Parameters
Value
(mm)
1. design frequency ƒr 2.4
2. dielectric constant εr 4.4
3. substrate height 1.6
4. patch width 38.39
5. patch length 29.82
6. ground plane width 43.83
7. ground plane length 43.83
8. Width of feed network for series array 2
9 Side of square 33.83
Table: 1 antenna design specifications
Fig. 1: Single antenna
Fig. 2: Return loss v/s frequency graph
Fig. 3: Gain v/s frequency graph
First band operating range =2.25-2.52
Second band operating range =3.50-3.82
Gain = 5 dB

Fig. 4: 2x1 Series feed Microstrip antenna array
Fig. 6: gain v/s frequency graph
First band Operating range =2.52-2.53
Second band operating range =4.82-4.9
Gain = 7.9 dB
Fig. 9: 4x1 series feed Microstrip antenna array.
Fig. 8: gain v/s frequency
First band Operating range =2.39 – 2.47
Second band operating range =4.023 – 4.12
Gain = 11.50 dB
Fig. 10: VSWR of 4x1 series feed antenna array figures

Fig. 11: Radiation pattern of 4x1 series feed antenna array
VI. RESULT AND DISCUSSION
Low gain of microstrip patch antenna is one of the major
drawback that restrict its wide usage. In the present work
the gain of microstrip square patch array is enhanced by
different series feed designs.the operating range of single
antenna is 2.25 to 2.53 & 3.50 to 3.82GHz & gain is 5db, for
2x1 antenna array operating range is 4.02 to 4.07 &4.82
to4.92 GHz &gain is 7.9db & for 4x1 antenna
arrayoperating range is 2.39 to 2.47 & 4.02 to4.12GHz, and
gain is 11.50db . The efficiency of proposed antenna array is
found to be 90 %. The VSWR of the antenna array is
between 1 to 2 at resonant frequency.
The simulation performance of proposed micro
strip square patch antenna array is analyzed by using IE3D
version 9.0 software at the design frequency of 2.4 GHz.
The performance specifications like bandwidth, radiation
pattern, gain etc are shown via graphs. The results of
different antennas designed are gathered and shown in the
following table.
Array
Operating
range
Return
loss
Gain
No. of
band
Single
antenna
2.25-2.52,
3.50-3.821
-14,
-15 5 2
Series feed
2x1
2.25-2.53,
4.82-4.92
-14.9,
-24
7.9 2
Series feed
4x1
2.33-2.48,
4.023-4.12
-24,
-19
11.50 2
VII. CONCLUSION
The characteristics of single square patch antenna, 2x1 &
4x1 series feed antenna arrays are studied. as we can see in
above table the gain of the 4x1 antenna array is maximum
as compare to other two antenna array so we can conclude
that gain is increased by increasing the no. patches in series
feed. These arrays can be useful for both s and c bands. The
proposed antenna array has been designed on glass epoxy
substrate to give a maximum radiating efficiency of about
90 % and gain of 11.50 dB using series feed 4x1 microstrip
antenna array.
REFERENCES
[1] “Design and Performance Analysis of Microstrip
Array Antenna”, Progress In Electromagnetics
Research Symposium Proceedings, Moscow,
Russia, August 18-21, 2009
[2] Diego R. Minervino,adaildo Gomes, “Array Of
rectangular Patch Micristrip Antenna For
Aerospace Applications," IEEE 978-1-1397
March 2013.
[3] D.M. Pozar.”Microstrip antennas”, IEEE
Transaction on Antenna and Propagation, Vol. 80,
pp. 79-91, Jan. 2009.
[4] A. Balanis; Antenna Theory ,Analysis and Design,
John Wiley & Sons Inc. 2nd
edition. 2009
[5] Zeland Software Inc.,”IE3D Electromagnetic
Simulation and Optimization Package,Version
9.35”, Zeland Software Inc.,Fremont,CA,2009
[6] D. Nashaat, H. A. Elsadek, E. Abdallah, H.
Elhenawy and M. F. Iskander, “Ultra-Wide
Bandwidth 2 × 2 Microstrip Patch Array Antenna,”
IEEE Transactions on Antennas Propagate, Vol.
59, No. 5, pp. 1528-1538, 2011
[7] Chuan-Ling Hu, Chang-Fa Yang and Shun-Tian
Lin, “A Compact Inverted-F Antenna to be
Embedded in Ultra-thin Laptop Computer for
LTE/WWAN/WI-MAX/WLAN Applications”,
IEEE Trans. AP-S/USRT,978-1-4244-9561, 2011.

Gain Enhancement of Series Feed Square Patch Microstrip Antenna Array for S band & C Band Applications

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Gain Enhancement of Series Feed Square Patch Microstrip Antenna Array for S band & C Band Applications