This document describes the design of an octagon-shaped microstrip patch antenna for multiband applications. Three antenna designs are presented: a simple rectangular patch, a patch with a single octagonal slot, and a patch with five symmetrical octagonal slots. Simulation results show that the number of resonant bands increases from three bands for the rectangular patch to six bands for the patch with five slots. Parameters like return loss, directivity, gain, and radiation efficiency are evaluated to analyze the multiband performance for wireless applications like WLAN. The addition of slots improves the bandwidth and radiation characteristics of the antenna.

1. 36 | INTERNATIONAL JOURNAL OF APPLIED SCIENCE AND TECHNOLOGY (Vol. 4, Issue 2)
ISSN 2231-3842 (Print) ISSN 2277-8691 (Online)
Design of octagon shape microstrip
patch antenna for multiband application
Abstract— In this work three rectangular microstrip
patch antenna is presented on glass epoxy FR4 substrate
having thickness of 1.6 mm. In these three antennas one
is simple rectangular patch antenna and the other two
are slotted patch design in the shape of octagon. Probe
feed technique is used in all the designs. The multiband
behaviour is analyzed using two slotted forms of the
designed patch antennas. The proposed antenna covers
multiband frequencies in the range from 1.6 to 5.9 GHz.
It is simulated using IE3D simulator. Electrical
parameters of the antenna like return loss; radiation
pattern, directivity & VSWR exc. are investigated. The
relationship between geometric sizes of the patch and the
electrical parameter speciûcations of the antenna is
researched.
Index Terms: Multiband IE3D, Octagon.
I. INTRODUCTION
Microstrip antenna is attractive elements at
microwave frequencies due to their inherent
advantages, such as conformability and simplicity
of design [1]. A microstrip patch antenna has a
conducting patch that made ofmetals such as copper
or gold, printed on a grounded dielectric substrate.
These antennas are low proûle, light weight, easy
fabrication, and nonplanar surfaces compatible with
MMIC design. A conventional microstrip patch
antenna have the disadvantage of narrowbandwidth
this poses a challenging task for the microstrip
antenna designer to meet the broadband technique
[2,3,4]. A big number of microstrip patches have
been developed that is used in wireless application.
Several shapes are square, rectangle, ring, ellipse,
pentagon, kite shape are introduced. In contrast to
patch configuration the antenna with slot gives
enhanced characteristicsincluding wider band width
and low conductor loss and better isolation [3]. In
modern wireless communication system and
increasing other wireless applications, wider band-
width, is required, traditionally each antenna
operatesat a single frequencyband, where a different
antenna is needed for different application. This will
cause a limited space and place problem. In order to
overcome this problem, multiband antenna can be
used where a single antenna can operate at many
frequency bands. Recently many new technologies
have been proposed for multiband antenna design
[4-8]. The regular microstrip antennas
configurations, such as rectangular and circular
patches have been modified to rectangular ring and
circular ring bycutting slots toenhance the BW. The
larger BW is because of a reduction in the quality
factor Q of the patch resonator, which is due to less
energystored beneath the patch and higher radiation
[9- 13]. In this paper, octagonal slotted microstrip
patch antennas are designed in calculating all its
geometric characteristics easily make this shape
usage advantageous in microstrip patch antenna
design.Although manyslottedpatch antenna designs
are available, but this design is different in shape.
Performance simulations of antenna are performed
on IE3D software, which is based on the method of
moments [14].
II.ANTENNA GEOMETRY
The basic design of microstrip patch antennas is
given through the rectangular microstrip patch and
runs through two slotted microstrip antennas to
generate multiband characteristics. The initial
dimension of the patch is taken at 2.4 GHz bytaking
Vishant Kumar Chaudhary
Shobhit University,
Meerut
Sudarshan Kumar
ECE Department,
IIMT Engineering College,
Meerut
Niraj Singhal
Shobhit University,
Meerut

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the FR4/glass epoxy substrate and the height of
substrateis1.6 mm, losstangent 0.02 andtherelative
dielectric constants of the substrate is 4.4. The basic
formulae for length andwidth aregiven below[3,14].
Where,
c = Velocity of light in free space
f0 =Operating resonant frequency
r = Relative dielectric constant
reff =Effective dielectric constant of the
substrate
h = Height of the substrate
W = Width of the substrate
The calculating dimension of the rectangular
microstrip patch is length L=28 mm and width W=3
mm. The microstrip patch antenna is designed in
three forms one design a simple rectangular patch
that is and in another patch a slot is build in the
patch in form of octagon from the upper radiating
patch, the radius of the octagon is nearly ë/8 that is
7 cm. In the third design four additional octagon of
radius slot ë/16 is cut from the upper radiating patch.
These four additional slot are symmetricallylocated
at (10, 10), (-10, 10), (10,-10) and (-10,-10). The
designed patch antennas is shown in figure1.
Figure 1. Antenna Designs (a) Zero Slot (b) Singe Slot
(c) Five Slots
III RESULTS AND DISCUSSIONS
Fig. 2 shows the variation ofreturn loss with the
frequency for the zero, single and five slotted form
of microstrip patch antenna. The return loss curve
shows that the resonating band for the zero slotted
patch antenna is three, for the single slotted patch
antenna is four and for the five slotted patch antenna
is six. This showsthat designed patch antennas show
the multiband behaviour.
(a) Zero Slo
t
(b) single slot

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(c) Five slots microstrip patch antenna
Figure 4 shows the comparison curve for return
loss of all the three forms of the designed antennas.
which shows the combined comparative curve for
the return loss for zeroslot, single slot and five slots,
in zeroslotted form there are three bands with return
loss less than -10dB and minimum value of return
loss is less than -15dB, in single slotted form there
are four bands with return loss less than -10dB and
minimum return loss is approximately-11dB and in
five slotted form there are six bands with return loss
less than -10dB and the minimum value of return
loss approaches nearly up to -35dB. So the return
loss minimizes as increasing the slots in the patch
antenna.
Figure 4 Comparison curve for return loss S11
(dB) Vs frequency
for zero slot, single slot and five slots patch antenna.
Other important parameters such as Directivity,
Gain and Antenna efficiency are also simulated for
the designed antennas. From Fig. 5, the curve is
drawn in between Directivity and frequency and it
is noticeable that average value of directivitystands
at 8dBi and approaches up 10.5dBi for the zero
slotted form of the antenna. Fig. 6 shows the curve
between the total field gain and frequency. Fig. 7
shows the curve between radiation efficiency and
frequency.
Figure 5. Antenna directivity comparison curve for zero slot,
single slot and five slots
Figure 6. Antenna Total field gain comparison curve for zero
slot, single slot and five slots

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Figure 7 Radiation efficiency comparison curve for zero slot,
single slot and five slots
Fig. 8 show the 3-D radiation pattern for zero
slot single slot and five slots rectangular patch at
the frequency 2.445 GHz, 5.3 GHz and 4.48 GHz
respectively, in all the three design the pattern are
nearlyomni directional and shows the positive gain,
or we can say the antenna can be used as a
transmitting as well as receiving antenna.
(a) Zero slot (at 2.445GHz)
(b) Single slot (at 5.3 GHz)
(c) Five slots (at 4.48 GHz)
In this paper a octagon shape slotted multiband
microstrippatch antennas issimulated. The proposed
antennas have slotted geometry. The performances
of the said antenna are studied for different number
of slots. It is found that the as the number of slots
are increased, the operational frequency band also
increases. For zero slot three resonant frequency
bands occur, for single slot four resonant bands
occursand for five slots sixresonant frequencybands
occurs. These antenna can be used at various
application such asWLAN-IEEE-802.11 (a, b, g and
n). Therefore the proposed antennas have satisfactory
performance for use as a multiband communication
antenna.

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