ISSN 2278-2508
SKIT RESEARCH JOURNAL
AN INTERNATIONAL JOURNAL OF ENGINEERING, SCIENCE, HUMANITIES AND MANAGEMENT
INNOVATION & EXCELLENCE
vlrks ek ln~xe;
SWAMI KESHVANAND INSTITUTE OF TECHNOLOGY,
MANAGEMENT & GRAMOTHAN
VOLUME 4; ISSUE 1: 2014
Editor in Chief : Prof. S. L. Surana
www.skit.ac.in
VOLUME 4; ISSUE 1: 2014
SKIT RESEARCH JOURNAL
Bandwidth Enhancement of Modified Rectangular
Microstrip Antenna with W shaped slot
for Wi-Max Application
Dheeraj Bhardwaj1, Maninder Singh Lakha2 , Komal Sharma3
Department of Physics, 2Department of Electronics and Communication,
1,2
Birla Institute of Technology, Mesra, Ext. Center Jaipur
3
Swami Keshvanand Institute of Tehnology Management & Gramothan, Jaipur
1,3
1
Email- dbhardwaj.bit@gmail.com
Abstract: Microstrip antennas caught the attention of many
designers in the last decade due to its numerous advantages; on the
other hand narrow bandwidth is a major disadvantage of
microstrip antenna in practical applications. In this paper the
effect of increasing the finite ground plane on a probe fed W-slot
microstrip antenna was proposed which is operated at 2GHz to
4.5GHz.This band is currently being used for the IEEE 802.11c &
IEEE 802.11s standard and other industrial, medical and scientific
applications. A rectangular microstrip antenna designed with two
resonance frequencies 2.61GHz and 3.33GHz with 42.53%
bandwidth.The directivity of the antenna are 7.49dBi and 7.99dBi.
The gain of the antenna are 3.25dBi and 1.32dBi corresponding to
the resonance frequencies. The antenna designed on Reinforced
PTFE, RT Duroid 5880, that had a relative dielectric constant 2.93,
a loss tangent 0.025 and thickness h=8mm.
light weight and broad bandwidth. The microstrip antenna suits
the features very well except for its narrow bandwidth. The
conventional microstrip antenna could not fulfill this
requirement as its bandwidth usually ranges between 1 – 3%.
A novel miniature wideband rectangular patch antenna is
designed for wireless local area
network (WLANs)
applications and operating in 5-6 GHz ISM band, and wideband
applications. The antenna has the Network (WLAN) products is
booming rapidly with the roll out of IEEE 802.11c products into
the home, public, and office environments. With the increasing
consumer demand for wireless multimedia, even higher
throughput will be required. Hence, the IEEE 802.1la and the
HIPERLAN/2 standards are designed and finalized to
accommodate this demand by providing transmission data rates
up to 54 Mbps in the 5-GHz ISM band
1. INTRODUCTION
Antenna is a transducer designed to transmit or receive
electromagnetic waves. Microstrip antennas have several
advantages over conventional microwave antenna and
therefore are widely used in many practical applications.
Microstrip antennas consist of a radiating patch on one side of
2. ANTENNA DESIGN
Designing an antenna meant that the antenna dimension could
be bulky, which is un-welcomed. Owing to its objective is to
design a reduced size microstrip antenna; the design idea was
taken from broadband antennas and rectangular patch antenna.
Hence the chosen shape of the patch was cut with a w-slot.
The geometry of the rectangular microstrip patch antenna
without slots is presented in Figure.1. This antenna is
resonating at 2.4GHz as shown in figure 2
dielectric substrate (Єr≤ 10), which has a ground plane on the
other side. In recent years, the popularity of wireless
applications is ever increasing in the industry as well as in our
very own society. There is a very large demand for wireless
applications because of its mobility. This is evident as the use of
mobile telephones which is integrated with wireless data
services is very common these days. Portable devices which
support data and telephony are being used in a mobile
computing environment. There is a large investment that has
been put into wireless communication with the major
companies in the telecommunication industry. This shows that
wireless applications are gaining an increase in its usage in our
society. Some particular application that has experienced this
trend are Television broadcasts, Microwave oven, Microwave
devices/communications, radio astronomy, mobile phones,
wireless LAN, Bluetooth, ZigBee, GPS and two-way radios
such as Land Mobile, FRS and GMRS radios, amateur radio,
microwave devices/communications wireless LAN, Radio
astronomy, In this design, the applications that are selected to be
studied are the 2GHz to 4.5GHz frequency band which is based
on the 802.11c&s standard. This frequency band is very popular
due to its low cost. WLAN antennas required to be low profile,
W
L
Fig 1: Geometry of rectangular patch microstrip antenna
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SKIT RESEARCH JOURNAL
Fig 2: Variation of Reflection coefficient v/s resonance frequency
The conventional rectangular microstrip patch antenna is
having low bandwidth. So to improve the performance of this
antenna we modified it. We insert some slits on CRMPA. As we
energized it at feed location X=3mm and Y=14mm the antenna
is start resonate at 2.4GHz having Gain 0.55dBi and
Bandwidth 16.6%. This is still very low. It means the antenna
required further modifications.
Now we insert w-slot in rectangular microstrip patch antenna
with four slits. This modified geometry of rectangular
microstrip w-slot patch antenna with four slits is presented in
Figure3.This rectangular w-slot patch with a pair of slits one is
inserted at the upper-right side, second is inserted at upper-left
side third is inserted at lower-left side and forth is inserted at
lower-right side of a rectangle is designed on “Reinforced
PTFE, RT Duroid 5880” substrate of thickneess 8 mm and
relative permittivity is 2.93.
In this work, co-axial probe feed technique is used as its main
advantage is that, the feed can be placed at any place in the patch
to match with its input impedance (usually 50 ohm). The E. M.
Simulation IE3D software is used to design and simulate the
final modified rectangular patch antenna.
Fig 3: Geometry of w-slot patch microstrip antenna with four
rectangular slits
3. RESULT AND DISCUSSION
The simple patch antenna is simulated first using IE3D
software. But the bandwidth obtained is very less.
Hence slits are inserted into the w-slot patch as the inductive
loading produced by the inserted slits as they result in
increasing the electrical length of the excited patch surface
current path and then a rectangular microstrip antenna with slits
is simulated using IE3D software. The modified patch is shown
in figure 3.
The figure 4 shows the variation of reflection coefficient with
frequency. It shows that the modified antenna is resonating at
two resonance frequencies 2.613GHz and 3.334GHz. We
achieve the bandwidth of antenna 42.53%.
The simulated VSWR for the two considered resonating
frequencies 2.613GHz and 3.334GHz are 1.0743 and 1.0293
respectively, which are close to unity as shown in figure 5.
Table 1: Design Parameters of rectangular patch antenna with slits
Parameters
h
Wg
Lg
A
B
C
D
E
Ws
Ls
Design
Considerations
8mm
36mm
26mm
2mm
11mm
16mm
4mm
4mm
14
18
Fig 4: Variation of Reflection coefficient v/s resonance
frequency of modified w-slot patch antenna.
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But impedence at lower frequency 2.613GHz is 50.826(Re), 3.452(Im). impedence at higher frequency 3.334GHz is
49.20(Re), -1.19(Im).
Figure 8 and 9 shows the 2D Polar radiation pattern i.e. gain
varies angle. The patterns are identical in shape and nature at
2.57GHz. It means the direction of maximum radiations is
normal to the patch geometry as shown in below figure 9.
At resonance frequency 3.3GHz the direction of maximum
radiation pattern is slightly right side of the pattern.
Fig 5: Variation of VSWR v/s resonance frequency of modified antenna
The simulated results show that the input impedances at two
resonating frequencies 2.613GHz and 3.334GHz are close to
50-ohm impedance of the feed line considered in the present
work which is shown in Figure 7. These results indicate that
simulated antenna is nicely matched with the feed line and very
little reflections are taking place at the feed location.
The variation of simulated gain with frequency is given in
Figure 6, which shows that gain with respect to these two
resonating frequencies is 3.257dBi and 1.32dBi respectively.
These two gain values are low and need further improvement.
Fig 8: 2D Radiation Pattern of TPMATRS at 2.57GHz
Fig 6: Variation of Gain v/s resonance frequency
Fig 9: 2D Radiation Pattern of at 3.301GHz
Fig 7: Smith chart of modified antenna
Fig 10: Variation of Efficiency v/s resonance frequency of modified antenna
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Table II. Comparison between Antenna Parameters
of various rectapatngular antennas
The variation in simulated radiation efficiency with frequency
is shown in Figure 10. The simulated results shows that
maximum radiation efficiency 37.67% is achieved for
resonating frequency 2.613GHz. But radiation efficiency at
higher frequency 3.334GHz is comparatively
low
21.52%.The radiation efficiency is low, but it can be improved
by applying substrate material having lower losses.
Antenna
Geometary
Conventional
Patch (h=8mm)
Dimensions Resonance Gain Bandwidth
(mm)
frequency (dBi)
(%)
(GHz)
W=26,
2.40
0.55
16.6
L=36
Rectangular
W=26,
patch microstrip
L=36
antenna with
A=2, B=11
four rectangular C=16, D=4,
slots (h=8mm)
E=4
4. CONCLUSION
The paper presents a broadband antenna resonate at two nearby
frequencies for the communication systems for many
applications. The analysis is carried out by considering a
substrate material with the higher loss tangent value still
reported simulation results are very encouraging. With this
antenna, we get much improved bandwidth 42.53% at center
frequency 3.334 GHz in comparison with a rectangular patch
antenna (having band width 16.6%). The directivity up to 8dBi
may be achieved. These values may be increased further with
the application of low loss materials. We have carried out this
analysis by considering the parameters of Reinforced PTFE, RT
Duroid 5880 substrate due to the availability of this material
with our group. The work requires extensive experimentation
before reaching any possible thought for its application. The
patch antenna is simulated first using EM simulation IE3D
software.
2.613
3.334
3.257
1.320
42.53
5. ACKNOWLEDGEMENT
The authors express their sincere thanks to Professor Deepak
Bhatnagar for providing simulation facilities at University of
Rajasthan.
[1]
[2]
[3]
81
REFERENCES
Compact and Broadband Microstrip Antennas, Kin-Lu Wong, John
Wiley & Sons, 2004.
Dheeraj Bhardwaj, Komal Sharma and Deepak Bhatnagar “Dual band
and Broadband Rectangular Patch Mircostrip Antenna with T Shaped
Slot for WiMax Application”, International Journal of Engineering
Research and Development, Volume 3, Issue 12, PP. 14-21,September
2012.
Dheeraj Bhardwaj, D. Bhatnagar and S. Sancheti, “Design and
Development of M-shaped Dual Frequency Microstrip Antenna for
Modern Communication Systems”, IETE 39th Mid term Symposium on
Recent advancements in Broadband Systems, April 12-13, 2008, Jaipur..