International Journal of Engineering Trends and Technology (IJETT) – Volume 22 Number 11 - April 2015
Design of small director array for low-profile smart
Antennas achieving higher gain using Matlab
M.Jahnavi 1, N.Hari Prasad 2, B.Karunakar Reddy 3, M.Puthanial 4
123
UG Students, 4Associate professor, Department of Electronics and communication Engineering,
Saveetha School of Engineering, Saveetha University
Thandalam, Chennai- 602105, India
Abstract— a small director array (SDA) is a gain improving
section of antenna which acts as low-profile smart antenna by
using fixed or reconfigurable array. This property of fixed or
reconfigurable array of an antenna can be achieved by using
switched parasitic elements. By using these parasitic elements
large gain improvement can be obtained in SDA using Yagi-Uda
configuration [1]. Parasitic elements are used to supply the
current indirectly to the antenna instead of direct supply to the
antenna which may lead to the damage of the antenna. Parasitic
elements have high resistance so that they may select the desired
current which prevents the damage. The height of the array is
reduced by 50% by using small directors in the standard YagiUda antenna. A steerable switched parasitic arrangement is used
in reconfigurable SDA through which it can be able to rotate
from 00 to 3600 [2] and also improve the had the advantages of
low cost and low power consumption, thus it is favourable for
applications in small satellites, high speed radio communications,
3G, 4G channel allocations, telecommunication networks.
the directors used in the set up. The length of the director of a
standard Yagi-Uda antenna is 0.45 λ which is larger that of
height [6].
Keywords - Small director array, Yagi-Uda antenna.
II. SIMULATION TOOL
The simulation is done by using the version of MATLAB
(R2009b). Matlab is a software tool, which is used for
simulating antennas and its Parameters [7].
To determine the radiation pattern
To get the array pattern of directional array
To get the number of array elements
To predict the gain of the antenna
To obtain the array factor of an antenna
To determine the front to back ratio of the antenna.
I. INTRODUCTION
Antenna is a transducer which acts as an interference
between the circuit and the free space. Smart antennas are one
of the technologies which are drastically improving in the area
of communication [3]. It consists of multiple antenna elements
which can generate multiple beams of signals. They are used
to get high diversity gain and special division multiplexing
which in turn increases the capacity of the communication
system. The signals that pass through the antenna array should
distribute the signal with equal phase and amplitude in order
to achieve the power combination. To attain such coherent
phase and amplitude in smart antenna it can be possible
through the usage of cohere transceivers [4] [5]. The usage of
coherent transceivers can make the antenna element to be
large and it makes the antenna too costly. In order to
overcome the problem of complexity Yagi-Uda antenna can
be used to replace the coherent transceivers his document is a
template.
Yagi-Uda antenna is a type of antenna which contains two
elements called as parasitic elements and driven elements.
Reflectors and Directors together can be called as parasitic
elements. Driven elements are the elements which are used to
connect to the other peripheral devices. Parasitic elements are
used as a supply unit to the antenna. Reflectors are always
small in dimension when compared to the directors. In YagiUda antenna the gain of antenna depends upon the number of
ISSN: 2231-5381
Reflector
Directors
Driven element
Fig 1: Yagi-Uda antenna with five directors
III. ANTENNA DESIGN
The design of the small director antenna mainly depends
upon the design of the array of the antenna [8] [9]. The
antenna can be designed through the general antenna
specifications. The antenna array can be designed through
multiple antennas which consist of the design of array
elements along the array factor [9]. The radiation pattern of
the array factor of a linear SDA antenna array can be designed
and represented according to the given input values. The small
directional array can be designed by calculating the array
factor and the array element of the antenna [10]. The array
pattern (AP) can be calculated with the product of the array
factor (AF) and the array element (AE) [11]
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AP=AE*AF
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International Journal of Engineering Trends and Technology (IJETT) – Volume 22 Number 11 - April 2015
The small director array can also be used at the BTS
receivers which work on the process of uplink [12] [13]. At
the receiver the required digital data can be obtained by
estimating the spectrum of the signal sent at the input and also
by estimating the angular transmission of the signal [14] [15].
S.no
Antenna
elements
1
2
3
4
5
6
7
1
2
3
4
5
6
7
Radiation Beam Pattern
Current
Phase
induced
induced to
Anticipated
for each
each
Gain values
element
element
2
10
2.5
3
20
5
4
30
7.5
5
40
8.5
6
50
9.5
7
60
10.5
8
70
11.5
Fig 2: Radiation pattern of the antenna
Table 1: Represents the number of elements and the current along with the
phase induced to each element with the approximate gain values
IV. SIMULATION RESULTS
The design of the small director array antenna consists of
the below obtained simulation results. By using the Matlab
software the radiation pattern of the antenna can be obtained
and the graph has been plotted along the different angles of
the plane and is represented through the polar form.
The direction angle of the designed antenna is plotted
along the X-plane and the Y-plane. The array pattern of the
directional antenna, the array factor of the antenna and the
array elements of the antenna can be plotted in the 3D
dimensions. The plots have been shown in the following
simulation patterns.
Fig 3: Represents the direction angle of the antenna
The gain of the antenna can be considered by taking the
major lobe into consideration. If the major lobe is narrow
then the bandwidth is less and more number of signals can
pass through the antenna. If the major lobe is wide then the
bandwidth is more and less number of signals can pass
through the antenna
Fig 4: Array pattern of directional array
ISSN: 2231-5381
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International Journal of Engineering Trends and Technology (IJETT) – Volume 22 Number 11 - April 2015
Fig 8: Radiation pattern of the antenna
Fig 5: Represents the array factor of the antenna
V.ANTENNA GAIN CALCULATIONS
Antenna gain can be calculated by calculating the antenna
efficiency and the directivity of the antenna
A. Directivity of antenna:
The directivity of the antenna can be measured with the
help of the far field power pattern.It can be related to the
radiation intesity which is related with the solid angle.
4πFmax(θ,ψ)
ʃ 02π ʃ 0π F(θ,ψ)sinθdθdψ
Here D is called as directivity and generally it is always
greater than 1(D≥1)
D=
B. Antenna Efficiency:
Fig 6: Representation of the array element
Antenna efficiency is the losses of the antenna.efficiency
can be given as
et =er ec ed
er is the matching efficiency, ec and ed are the ohmic losses
and the dielectric losses. The antenna gain is almost related to
the antenna diectivity. For an efficient antenna the antenna
gain must be lossless. Hence the gain of antenna can be given
as
G=et D
Where et is the total efficiency of the antenna and D is
called as the directivity of the antenna. The gain of the
antenna mainly depends upon the number of the elements
used.
VI. CONCLUSION
Fig 7: Represents the direction angle of the antenna
ISSN: 2231-5381
Thus the simulation of the small director antenna has been
determined and the gain achieved in the design can be showed
up to 10db. The height of antenna is also reduced further than
the standard Yagi-Uda by reducing the size of the directional
element of the antenna. The gain improvement of the antenna
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International Journal of Engineering Trends and Technology (IJETT) – Volume 22 Number 11 - April 2015
can be achieved by increasing the number of director elements
in the antenna. A configurable SDA was designed in order to
achieve the steerability in the antenna. The cost of the antenna
also gets reduced because of the reconfigurable array elements
which are proved to be of low cost.
SUMMARY
Puthanial.M is pursuing her Ph.D. in the area of wireless
communication - smart antennas under the guidance of
Dr.P.C.Kishore Raja
M.Jahnavi, N.Hari Prasad, B.Karunakar Reddy - under
graduate students of Electronics and Communication
department worked closely on this project under the guidance
of M.Puthanial.
[17]
[18]
Simulation And Performance Analysis Of 2x2 Microstrip Patch
Antenna Smart Array, Puthanial.M, Dr. P.C.Kishore Raja International
Journal of Applied Engineering Research (IJAER),Volume 10, Number
4 (2015)
Comparative Analysis of Microstrip Patch Antenna using EZNEC and
ADS, Puthanial.M, Shubhashini.R, Pavithra.K, Priyanka Raghu, Dr. P.
C. Kishore Raja ,International Journal of Engineering Trends and
Technology. 2014;16(2):54-57 DOI 10.14445/22315381/IJETTV16P212
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