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ICICES.2017.8070774

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INTERNATIONAL CONFERENCE ON INFORMATION, COMMUNICATION & EMBEDDED SYSTEMS (ICICES 2017)
DESIGN AND ANALYSIS OF CIRCULAR MPA USING MULTI-LAYER
SUBSTRATE SANDWICH FOR BANDWIDTH ENHANCEMENT
Manjunath G
Naseeruddin
Sadyojatha K M
Ballari Institute of Technology &
Management
Ballari, India
manjutc000@gmail.com
Ballari Institute of Technology &
Management
Ballari, India
naseeruddin@bitm.edu.in
Ballari Institute of Technology &
Management
Ballari, India
saddukm@gmail.com
Abstract—In this paper, the design of circular microstrip
patch antenna with sandwiching the substrates has been
proposed for bandwidth enhancement. The proposed antenna is
designed at 2.7GHz (S-band) using High Frequency Structural
Simulator. The circular patch antenna is designed on two
different substrates, FR4_epoxy and RT Duroid 5880™ and
fabricated on the three layer FR4-epoxy substrate. The effect of
dielectric constant, substrate stacking on the performance of an
antenna system is compared and results from the simulator are
analyzed. The result analysis shows that the bandwidth of this
antenna has increased 2.5 times with three layer stacking at 10
dB return loss and directive gain of 4.7dBi. The work can be
enhanced in the future using metamaterials to reduce the
antenna weight and to increase the bandwidth of operation.
Keywords—Metamaterial; Finite Element Method;
wideband; Substrate Sandwich
Ultra
I. INTRODUCTION
Recently, demand for microwave, and wireless
communication systems in various applications is growing.
This is a major driving factor for researcher to improve
antenna performances. Modern communication systems such
as Wireless local area networks (WLAN), Bluetooth, mobile
handsets require lightweight, small size and low cost antennas
[1]. The choice of microstrip antenna technology can fulfill
these requirements. The need for broadband wireless
communication systems is growing drastically, and the
frequency of operation is shifting progressively towards
millimeter-wave region. In recent years, this has shaped
interest in developing low-profile multilayer microstrip
antennas [7] with a broadband and constant gain for wireless
communication systems to increase the data rate and also to
cope with an increased number of users. In this context,
enough background survey is carried out and cautiously
investigated various methods for enhancing bandwidth.
In present work, the design and optimization of a circular
microstrip antenna with three layer sandwich substrate without
any air or foam layer is proposed for UWB applications. The
antenna design constraints are discussed in the next section.
The proposed antenna configuration differs from the
conventional three-layer, aperture-coupled microstrip antennas
where the three substrates in this configuration are not
separated by a ground plane. The sandwich substrate is used
for enhanced impedance bandwidth in addition to keep the
driven patch compact and thus the overall antenna size is
reduced. The details of the parametric study and expected
results are tabulated in the simulation results part. The design
and parametric optimization were conducted with the help of
HFSS EM simulation software [4].
II. BACKGROUND SURVEY
One of the most severe limitations of the conventional
microstrip antenna is the narrow bandwidth, which is typically
around a few percent. Over the years, various methods have
been proposed to enhance bandwidth.
It is well known that, the selection of feeding method plays
an important role in any antenna design context to parametric
demand and fabrication, proximity coupled feeding offers
impedance bandwidth of approximately 13%, but it is not so
easy to fabricate because during the fabrication, proper
alignment is required[5]. The methods offered to increase the
bandwidth are usually from the following variations of the
three approaches-one way is increasing the antenna volume.
This is accomplished by geometry modification that increases
the volume under the conductive patch. Another alternative
way is decreasing the substrate dielectric constant, or adding
additional coupled resonators, however it is not a better choice
to enhance bandwidth at the expense of antenna size and
moreover the availability of the substrate with small dielectric
constant is a very big issue. Another approach is perturbing
the antenna geometry to create or relocate resonances using
shorts and slots in the antenna, the conventional possible
methods in demand are antenna with defected ground structure
(DGS)[8][9], Electro Band Gap (EBG) structures[10][11].
Lastly the use of matameterial with negative refractive index
is the most effective choice, Use of metamaterial concept is
still modern and has more uncertainty benefiting at the same
time the in the reduction of antenna size to an unexpected
level. Moreover, the analysis with negative refractive index is
a challenging task [2].
It is very difficult to ensure the directional capability of the
antenna over a wide range of frequencies. It is not easy to
balance both gain and bandwidth because gain bandwidth
product should be equal to unity. Moreover, ordinary
wideband microstrip patch antenna will not transmit very short
pulse without distortion. For high data rate requirements,
directional high gain wideband microstrip antennas with
constant gain over the wide frequency band are required.
978-1-5090-6135-8/17/$31.00 ©2017 IEEE
INTERNATIONAL CONFERENCE ON INFORMATION, COMMUNICATION & EMBEDDED SYSTEMS (ICICES 2017)
Design of the low-profile directional microstrip patch antenna
for UWB wireless applications is more challenging. Balanis
suggested [5] that, by increasing the thickness of the substrate,
bandwidth enhancement can be possible. One way of
increasing the thickness is substrate sandwiching or substrate
stacking [7].
III. PROPOSED ANTENNA DESIGN
The circular microstrip patch antenna [6] is designed
effectively over multi layer substrate. Firstly the patch antenna
is designed with single FR4 substrate. Later the same antenna
has been modified over three layer FR4 substrate.
optimized to 15.1 mm. The fig 2 shows the geometry of the
circular patch antenna designed using HFSS. Coaxial feeding
is used in the design. The center of the patch is taken as the
origin and the feed point location is given by the co-ordinates
(Xf ,Yf ) from the origin. The feed point must be located at that
point on the patch, where the input impedance is 50 ohms for
the resonant frequency. Hence, a parametric optimization is
used to locate the feed point by moving towards the Xf axis
from the origin.
A. Circular patch antenna design
The circular patch antenna [3] has only one degree of
freedom, hence the performance mainly depends on the radius
of the patch.This does not change the order of the modes;
however, it does change the absolute value of the resonant
frequency. The structure of circular patch antenna is as shown
in fig 1.
Fig 2. Design of Circular Microstrip Patch Antenna Using HFSS
B. Antenna with three layer substrate sandwich
The same antenna is designed with stacking three FR4
substrates one over the other. Sandwich substrate is placed on
the ground copper plane and the patch is placed above the
substrate as shown in the fig 3.
Fig 1. Structure of Microstrip patch antenna.
The radius of the patch can be calculated by the following
equation found in[5]
(1)
Where,
Fig 3. Design of Circular Microstrip Patch antenna with 3 layer substrate
Using HFSS
(2)
The circular microstrip antenna is designed for the following
specifications:
Operating frequency = 2.7 GHz (S-Band)
Dielectric constant of substrate-ࢿr =4.4
Height of substrate -h = 1.6mm
Loss Tangent =0.02.
The design and analysis of an antenna becomes quite
easier due to the advancements in the software EM tools.
HFSS software is used for the design and simulation, which
utilizes finite element method to solve electromagnetic
problems. The patch antenna is designed with FR4 substrate
which has a relative permittivity of 4.4. Theoretically the
patch radius is found to be 15mm, but some sort of
optimization is required for practical suitability, hence it is
Similarly circular patch antenna has been designed using
RT Duroid 5880™ substrate (ࢿr=2.2).It is observed that the
antenna with small value of dielectric substrate gives good
enough performance at the expense of antenna size. The
design constraints are tabulated in the Table I.As per the
observation the size of the antenna can be reduced by
sandwiching the substrates.
Table I. Circular Patch Dimensions of Different Substrate Materials
978-1-5090-6135-8/17/$31.00 ©2017 IEEE
INTERNATIONAL CONFERENCE ON INFORMATION, COMMUNICATION & EMBEDDED SYSTEMS (ICICES 2017)
From the simulation process, the performance of an
antenna is characterized based on the antenna parameters such
as, return loss (S11), bandwidth, radiation pattern, and antenna
gain. These values need to be analyzed before the fabrication.
From the literature [5], the value of the return loss should be
much lower than -10 dB. This value is chosen by assuming
that only 10% of the power transmitted is reflected back or
results in loss. The circular patch is nearly matched to 50
ohms, hence the VSWR value is 1.05 and return loss is 31.83dB.
Ansoft
Name LLC Theta
IV. SIMULATION RESULTS & FABRICATION PROCESS
m1
0.0000
Ang
Mag
0.0000
4.9864
2D radiation pattern
-30
-7.00
-60
-19.00
-90
m1
0.0000
2D Radiation Pattern 1
Ang
Mag
0.0000
3.0347
HFSSModel1
m1
-2.00
Ansoft
Name LLC X
RETURN LOSS
Y
0.00 2.7000 -22.0481
m5
m10
2.6900 -25.0865
m11
2.6090 -10.0643
HFSSModel1
ANSOFT
Curve Info
dB(S(WavePort1,WavePort1))
Setup1 : Sw eep
dB(S(WavePort1,WavePort1))
m12
-5.00 2.7680 -10.0053
m11
-10.00
m12
-15.00
-20.00
m5
m10
2.00
2.25
2.50
2.75
3.00
Freq [GHz]
3.25
3.50
3.75
4.00
Fig 7. Return Loss V/S Frequency of the patch antenna with 3 layer substrate
-9.00
-60
150
Fig 6. 2D Radiation Pattern of the patch antenna with 3 layer substrate
dB(GainTotal)
Setup1 : LastAdaptive
Freq='2.7GHz' Phi='90deg'
30
120
-180
-30.00
ANSOFT
Curve Info
0
-30
90
-120
-25.00
Ansoft
Name LLC Theta
60
-13.00
-150
60
-16.00
It is clearly found that, circular patch antenna with
sandwiching the 3 layers FR4-epoxy can increase the antenna
bandwidth approximately more than twice than the antenna
with single substrate. Fig 4-Fig 8 are the various result plots
obtained from HFSS tool.
-23.00
-90
90
-120
120
-150
150
-180
Fig 4. 2D Radiation Pattern of the patch antenna with single substrate
Name
X
return loss
Y
0.00 2.7000 -48.0904
m3
m5
2.7343 -10.0856
m6
2.6665 -10.0637
HFSSModel1
Table II. Complete Summary of Simulation Results
ANSOFT
Curve Info
dB(S(WavePort1,WavePort1))
Setup1 : Sw eep1
m6
m5
dB(S(WavePort1,WavePort1))
-10.00
-20.00
-30.00
-40.00
m3
-50.00
2.00
2.25
2.50
2.75
3.00
Freq [GHz]
3.25
3.50
3.75
Figure 5. Return Loss V/S Frequency of the patch antenna with single
substrate
4.00
The fabricated structure of patch with single substrate and
antenna with 3 layer sandwich are shown in Fig 8.
978-1-5090-6135-8/17/$31.00 ©2017 IEEE
ANSOFT
Curve Info
dB(GainTotal)
Setup1 : LastAdaptive
Freq='2.7GHz' Phi='90deg'
30
-1.00
The simulation results are the virtual testing results
obtained from the simulation tool (HFSS). In practical, the
performance of the antenna can vary due environmental and
many other factors leads to mismatching between the
simulation and practical results; this can be reduced by
considering these factors in the design simulation and through
the proper practical survey.
From the above observations, the antenna performance can
be characterized with respect to different dielectric materials.
For some applications the results obtained from the antenna
with FR4_epoxy substrate will not be enough because of its
large ࣅr value. So an antenna can be designed on low loss
material which has small ࣅr value (Eg: RT Duroid 5880™).
The circular patch antenna is also designed on RT Duroid
5880 substrate (ࣅr= 2.2 and loss tangent=0.0009) for better
radiation characteristics. The Table II shows the summary of
the simulation results.
HFSSModel1
0m1
INTERNATIONAL CONFERENCE ON INFORMATION, COMMUNICATION & EMBEDDED SYSTEMS (ICICES 2017)
[2]
[3]
[4]
[5]
[6]
Fig 8. Fabricated antenna prototypes
V. CONCLUSION AND FUTURE SCOPE
The circular microstrip patch antenna using different
dielectric materials are designed and fabricated individually
according to the proposed design specifications with proper
optimization of the design parameters. The result analysis of
all the designed antennas are tabulated together and compared
with respect to the corresponding simulation results. From the
above work it is found that, the results obtained are more
satisfactory. Since the constraints like dielectric constant, loss
tangent and the substrate thickness are the important
parameters in designing micro strip patch antennas. The
bandwidth enhancement has been done by sand witching the
substrates. The proposed antenna can also be designed in
future using Metamaterials to reduce the antenna weight, and
increase the bandwidth of operation.
Pai Yen Chen and Andrea Alù, “Sub-Wavelength Elliptical Patch
Antenna Loaded With Negative Metamaterials,” IEEE
Transactions on Antennas and Propagation, September 2010,
ISSN: 0018-9262, DOI: 10.1109/TAP.2010.2052578, Vol. 58,
Issue. 9, pp- 2909-2911.
Randy bancroft, “Microstrip and Printed Antenna Design,” PHI
Pvt Ltd, 2nd Edition, new Delhi-2006, ISBN-13: 978-18-849-32588.
M. Himdi, “Report on design tools and software benchmarking,”
European Commission – 6th Framework Programme, Antenna
Centre of Excellence, 20th December 2005, pp 1-89
C.A Balanis, “Antenna Theory Analysis and Design,”John Wiley
& Sons, INC. 2nd Edition, New York, 2005, ISBN: 978-81-2652422-8.
B. J. Kwaha, O. N Inyang & P. Amalu, “The Circular Microstrip
Patch Antenna-Design and Implementation”, International Journal
of Research and Reviews in Applied Sciences (IJRRAS), July 2011,
ISSN: 2076-7345, Vol 8, Issues 1, pp- 86-95.
[7]
Nasimuddin Z.N. Chen, “Wideband microstrip antennas with
sandwich substrate,” Institute for Info communication Research, 20
Science Park Road, Singapore. ]
[8] Neeraj Rao and Dinesh Kumar V “Gain and Bandwidth
Enhancement of a Microstrip Antenna Using Partial Substrate
Removal in Multiple-layer Dielectric Substrate,” PDPM Indian
Institute of Information Technology, Design & Manufacturing
Jabalpur, India.
[9] Liu WC , Wu CM, Dai Y. “Design of Triple frequency mictrostrip
fed monopole antenna using defected ground structure,” IEEE
Trans. Antennas Propag. 2011;59:2457-2463.Journel of
Electromagnetic Waves and Applications 1545
[10] Lee RQ , Lee KF . “Experimental study of the two layer
electromagnetically coupled rectangular patch antenna,” IEEE
Trans. Antennas Propag.1990; 38:1298-1302
[11] Samuel Silver, “Microwave Antenna Theory and Design,”
McGraw-Hill Book Company, INC. 1st Edition, New York,
Toronto, London, 1949, ISBN: 978-08-634-1017-8.
ACKNOWLEDGEMENT
This work is supported by Dept. of E&CE, Ballari Institute
of Technology and Management, Ballari. The authors would
like to thank the management, H.O.D and senior professors for
encouraging us for this research work.
REFERENCES
[1]
Max Ammann, “Design of Rectangular Microstrip Patch Antennas
for the 2.7 GHz Band,” Dublin Institute of Technology.
978-1-5090-6135-8/17/$31.00 ©2017 IEEE
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