DESIGN OF DUAL BAND DISSIMILAR PATCH SIZE ARRAY ANTENNA FOR WIRELESS APPLICATIONS

International Journal of Information Sciences and Techniques (IJIST) Vol.4, No.3, May 2014
DOI : 10.5121/ijist.2014.4305 31
DESIGN OF DUAL BAND DISSIMILAR PATCH SIZE
ARRAY ANTENNA FOR WIRELESS APPLICATIONS
R.Rajeswari1,
P.Sudharshini2
, S.V.Vidhya harini3
1
Assistant Professor, Dept. of ECE, VCET, Madurai
2-3
UG Student, Dept. of ECE, VCET, Madurai
Abstract-
This paper deals with the design of a dual band array antenna for wireless applications such as LTE (Long
Term Evolution), WiMAX etc…that resonates at 3.5 GHz and 5 GHz respectively. The substrate used for design
is FR4 (∈ =4.6) and the software used for simulation is Agilent ADS Momentum. The concept of dissimilar
patch size array antenna has been introduced. So patches of different dimensions have been used in the array
and their corresponding results are validated based on various antenna parameters like VSWR, gain, directivity
and power radiated.
Keywords-
Patch antenna; dual-band; LTE; WiMAX; MIMO
1. INTRODUCTION
The rapid growth of wireless communication systems has increased the demand for compact antennas
with multiband operating frequencies. In some cases, the bandwidth of the entire frequency range
could be covered with the antenna. Owing to their low-profile, low-cost, and low-mass features,
microstrip antennas can be easily placed inside packages, making them a suitable choice for numerous
consumer applications. There is huge demand for new kind of antennas such as small antennas, multi-
frequency antennas, broadband antennas for mobile and satellite communication systems. A dual band
antenna is an antenna designed for use on two different bands which provides various applications
such as Wireless Communications, satellite communications, Area monitoring, Forest fire detection,
Disaster prevention. A patch antenna (also known as a rectangular Microstrip antenna) is a type of
radio antenna with a low profile, which can be mounted on a flat surface. It consists of a flat
rectangular sheet or "patch" of metal, mounted over a larger sheet of metal called a ground plane.
Planar antennas [1] are preferred because of their small size and simple structure. One of the main
types of planar antennas is microstrip patch antenna. They are preferred over other planar antennas
because of their thin profile. A patch antenna is a piece of metal mounted on a substrate of thickness h
and dielectric constant ∈ . It is an easy to fabricate, low cost, small-sized and low weight antenna
[1].These properties of microstrip patch antennas make them most suitable for mobile devices. A
simple rectangular patch antenna typically resonates at a single resonance frequency Fr [2]. Multiple
Input Multiple Output (MIMO) is considered as a key smart antenna technology, to improve the
capacity of a communication channel at a greater extent [3], because it makes it possible to transmit
multiple data streams over a same frequency channel without increasing the physical bandwidth of
that channel [4].MIMO utilizes multiple antenna elements both at transmitter and receiver ends to
increase the data transmission rate by providing higher spectral efficiency [3].The 4G cellular mobile
communication standards, Long Term Evolution(LTE) and WiMAX[4], utilizes MIMO to provide
improved data rate of up to 1Gbps

32
II ANTENNA DESIGN
Our goal is to design a dual band microstrip patch antenna array at 3.5 GHz and 5.0 GHz using
ADS simulation software. We used microstrip line (edge feed) technique to feed the microstrip
patch antenna covering both the frequencies.
A. Two element antenna design
Substrate selection is the first practical step in designing a patch antenna. FR4 (∈ =4.6) is used as
substrate to design the patch antenna. These values are carefully chosen to meet our performance
and bandwidth requirement because dielectric material is crucial for determining the performance
of antenna. To achieve compactness, thin substrates are required but the bandwidth of antenna
decreases as height is reduced. Also with higher values of ∈ the patch size can be reduced but it
would also reduce the antenna bandwidth. So, a trade-off must be done between antenna
performance and its size [1, 5]. The empirical formulas in [6] are used here to obtain the initial
parameters of dual band patch antenna. The dimensions for different patch size are calculated.
The length of the large patch radiator is 22.2 mm and width is 28.1 mm whereas the length of the
small patch radiator is 14.565 mm and width is 19.7 mm. Length of the feedline is 12 mm and
width is 0.7 mm. Distance between the centers of both the feedline is 59.3 mm. (fig.1)
Figure 1(a) : Array of 2 elements with ideal ground plane covering both the frequencies of 3.5 GHz and
5.0 GHz.
Figure 1(b): Radiation pattern of two element array antenna.

33
B.Four element antenna design
small patch radiator is 14.84 mm and width is 19.7 mm. Length of the feedline is 12 mm and
width is 0.7 mm. Distance between the centre of both the 2 element feedline is 59.3 mm. Distance
between the edges of above and below radiator is 61.4 mm. The efficiency of the antenna is found
to be 70.096%.
Figure 2(a): Array of 4 elements with ideal ground plane covering both the frequencies of 3.5 GHz and 5.0
GHz.
Figure: 2(b)
Figure 2(b): Radiation pattern for four element array antenna.
C.Eight element antenna design
small patch radiator is 14.7 mm and width is 19.7 mm. Length of the feedline is 12 mm and width
is 0.7 mm. Distance between the centre of both the 2 element feedline is 59.3 mm. Distance
between the edges of above and below radiator is 61.4 mm. Distance between the centre of both
the 4 element array feedline is 121.7 mm. The efficiency of the antenna is found to be 73.05%.

34
Figure 3(a): Array of 8 elements with ideal ground plane covering both the frequencies of 3.5 GHz and 5.0
GHz.
Figure: 3(b)
Figure 3(b): Radiation pattern of eight element array antenna.
D. Sixteen element antenna design
The length of the large patch radiator is 21.3mm and width is 28.1 mm whereas the length of the
small patch radiator is 14.7 mm and width is 19.7 mm. Length of the feedline is 12 mm and width
is 0.7 mm. Distance between the centre of both the 2 element feedline is 59.3 mm. Distance
between the edges of above and below radiator in 4 element is 61.4 mm. Distance between the
centre of both the 4 element array feedline is 217.4 mm. Distance between the centre of both the 8
element array feedline is 190 mm.

35
Figure 4(a): Array of 16 elements with ideal ground plane covering both the frequencies of 3.1 GHz and
4.5 GHz.
Figure 4(b): Plot of return loss vs. frequency of sixteen element array antenna.
III RESULTS AND DISCUSSIONS
The return loss is determined for the two, four, eight element antenna respectively and a better
return loss was observed in eight element antenna and the results are tabulated in table I.

36
Array
element
Freq
(GHz)
Return loss,S(1,1),
(dB)
2 3.1 -16.18
4.5 -14.67
4 3.1 -25.39
4.5 -15.14
8 3.1 -19.64
4.5 -30.21
16 3.1 -21.37
4.5 -25.28
Table I: Comparison of return loss for different array element
The VSWR is determined for the two, four, eight element antenna respectively. The optimum
VSWR is in the range of 1.6 and we have achieved it in our antenna design and the results are
tabulated in table II.
Array element Freq
(GHz)
VSWR
2 3.1 1.36
4.5 1.46
4 3.1 1.28
4.5 1.52
8 3.1 1.39
4.5 1.32
16 3.1 1.19
4.5 1.11
Table II: Comparison of VSWR for different array element
Figure 4: Comparative study of radiation pattern of two, four, eight element respectively
The gain is determined for the two, four, eight element antenna respectively and a better gain of
9.250 dB was observed in eight element antenna and the results are tabulated in table III
Array element Gain (dB)
2 5.006
4 6.91
8 9.72
16 9.95

37
Table III: Comparison of Gain for different array element
The bandwidth is determined for the two, four, eight element antenna respectively. FL denotes
lower frequency and FH denotes higher frequency and the bandwidth is obtained in the range of
mega hertz and the corresponding the results are tabulated in table IV.
Antenna
array
elements
Freq
(GHz)
FL
(GHz)
FH
(GHz)
Bandwidth
(MHz)
2 3.1 3.10 3.15 50
4.5 4.24 4.32 80
4 3.1 3.12 3.19 70
4.5 4.50 4.61 110
8 3.1 3.12 3.21 90
4.5 4.54 4.67 130
16 3.1 3.10 3.20 100
4.5 4.46 4.57 150
Table IV: Comparison of bandwidth for different array element for two frequency 3.1 GHz and 4.5 GHz
IV CONCLUSION
A dual-band microstrip patch antenna array for LTE, WiMAX and other wireless applications is
presented. The antenna covers 3.1 GHz and 4.5GHz frequency bands .Good results are obtained
in terms of return loss, VSWR and array gain. The use of Agilent ADS software ensures that
there would not be large differences between the results of simulated and measurements of
fabricated antenna. The fabrication will be performed using the same FR4 substrate to compare
antenna results.
REFERENCES
[1] Constantine A. Balanis, Antenna Theory, Analysis and Design, Third Edition, John Wiley & Sons,
Inc. 2005.
[2] Y. X. Guo, K. M. Luk, K. F. Lee and Y. L. Chow, "Double U-slot rectangular patch antenna,"
Electronics Letters, vol. 34, pp. IS05-IS06,Sept. 1995.
[3] G. J. Foschini, "Layered space-time architecture for wireless communication in a fading environment
when using multi-element antennas," Bell Labs Technical Journal, pp 41-59, autumn 1996 [4]Martin
Sauter, Beyond 3G - Bringing Networks, Terminals and the Web Together, John Wiley & Sons
Ltd,2009
[5] Garg, R. Bhartia, P., Bahl, I., Ittipiboon, A., Microstrip antenna design handbook, Artech House,
Inc,2001..
[6] Weigand, G. H. Huff, K. H. Pan, J. T. Bernhard, "Analysis and design of broad-band single layer
rectangular U-slot microstrip patch antennas," IEEE Transactions on Antennas and Propagation, vol.
51, no. 3, March 2003.
Authors
Prof.R.Rajeswari, is working in Electronics and Communication Engineering
Department at Velammal College of Engineering and Technology, Madurai, received her
B.E degree (ECE) at K.L.N college of Information and Technology, Madurai , M.E
degree (Communication systems) at Sri Venkateswara College of Engineering, Chennai.
She has published several papers in National and International Conferences. Her areas

38
of interest are microwaves, Electromagnetics and Antenna Design. She is a Life Member of Indian Society
of Technical Education (ISTE).
P.Sudharshini was born on 03.04.1992. She pursues final year B.E in Velammal C
ollege of Engineering and Technology, Madurai. Her research areas include Antenna
design.
S.V.Vidhya Harini was born on 28.12.1992. She pursues final year B.E in Velammal
College of Engineering and Technology, Madurai. Her research areas include Antenna
design.

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