Improving the performance parameters of microstrip

IJRET: International Journal of Research in Engineering and Technology eISSN: 2319-1163 | pISSN: 2321-7308
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Volume: 02 Issue: 12 | Dec-2013, Available @ http://www.ijret.org 111
IMPROVING THE PERFORMANCE PARAMETERS OF MICROSTRIP
PATCH ANTENNA BY USING EBG SUBSTRATE
Gaurav Kumar Sharma1
, Narinder Sharma2
1
M.Tech. Scholar, Department of ECE, Amritsar College of Engineering and Technology AMRITSAR, PUNJAB,
INDIA, gaurav.bhanot@yahoo.com
2
Associate Professor, Department of EEE, Amritsar College of Engineering and Technology AMRITSAR, PUNJAB,
INDIA, narinder.acet@gmail.com
Abstract
The objective of this paper is to analyze the performance of electromagnetic band gap (EBG) antenna for base station
applications through simulation. The proposed analysis is carried out using the high frequency structure simulator (HFSS). In our
method, to overcome several intrinsic limitations of patch antennas such as constrict bandwidth, low gain, excitation of surface
waves, the EBG concept is applied. The patch antenna and patch antenna surrounded by the EBG cells are characterized in terms
of return loss and radiation pattern in an anechoic chamber.
Index Terms: Microstrip patch antenna, electromagnetic band gap structure, bandwidth, gain.
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1. INTRODUCTION
With the rapid development of wireless field, microstrip
antennas became more appealing in antenna community.
These antennas are low-profile, low price and dismount.
However, Surface waves are a major drawback for this type
of antenna as they lower the antenna efficiency. A narrow
impedance bandwidth is another limitation of patch
antennas. Two techniques have been applied to suppress
surface wave propagation, namely micromachining [1- 2]
and periodic structures called the electromagnetic band gap
(EBG) structures [3-6]. In microstrip antennas, EBG
structures environing patch element to suppress surface
waves to attain better side lobe and back lobe levels and
enhanced radiation efficiency. It has been shown in article
[7] that, placing EBG cells in E-plane is enough for surface
wave reducing and it is not required to have H-plane EBG
cells. This EBG structures is used in microstrip array
antennas between radiating array elements in E-plane to
come down mutual coupling between them by suppressing
surface waves. However, the consequences of EBG
structures environing the antenna can be considered as two
consequences, namely parasitic loading effect and cavity
effect. The parasitic loading effects enhance the bandwidth,
whereas the cavity effect diminishes the bandwidth. The
EBG cells placed in nearness of the radiating edges of the
antenna components provide the parasitic loading and
thereby bettered bandwidth [8]. On the other hand, the EBG
structures also reflect back a part of the energy that circulate
along the substrate of the antenna, thus acting as reflecting
walls across the antenna and thereby the cavity effect. With
elite rows of EBG structures, minus energy is reflected back
and the parasitic effect becomes prevailing. This contributes
to the significant enhancement in the bandwidths. As the
number of rows is increased, more of the energy circulate
along the substrate is reflected back and the cavity effect
becomes prevailing. This in turn enhances the Q-factor of
the cavity made by the EBG structures surrounding the
antenna and come down the bandwidths of the antenna. On
the other hand, front to back ratio (FBR) of the antenna
enhances with the number of EBG rows surrounding the
antenna, as anticipated, due to the suppression of surface
waves.
Since antenna radiation features, incubate resonant
frequency and radiation patterns are ascertained for the most
part by its shapes and size, altering its geometry
mechanically allow for a non-rational method to reconfigure
its radiation attributes. MEMS techniques incorporate
electrical and mechanical operates in a single component
using micro fabrication or micro aching technology, and can
be recognized with present semiconductor integrated circuit
serving [5–7]. Hence, MEMS based reconfigurable antennas
had been widely inquired [8–13]. By using printed circuit
board (PCB) techniques, planar wire antennas in the form of
filamentary conductive traces can be constructed with
inserted MEMS switches. A MEMS switch converts
dynamically the antenna length and enables dual or
multiband applications.
Antenna reconfiguration can also be projected electronics
switch such as PIN diodes, which are ordinarily used in
modern communications and radar applications. When the
diode switch is DC forward biased, it is at an “on” state and
is ideally a short circuit; while when the diode is reverse
biased, it is at an “off” state and the diode is open-circuited.
Placing a PIN diode in between two conducting traces,
could control electronically the efficient antenna physical
length. Planar microstrip antennas using PIN diode
switching for reconfiguration had also been investigated [4–
8].
Most reconfigurable antennas are grounded on the
dynamic control of the antenna physical length. It is possible
to design electronically tunable antennas by adapting the
attributes of the material where an antenna occupies. Ferrite-

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Loaded microstrip antennas are examples [2], where the
antenna features are aligned by the external magnetic fields
issued by a dc biased circuit.
Electromagnetic band gap (EBG) structures in printed
circuits are thin complex dielectric layers with periodic
metallic patterns (generally backed by a metal ground
plane), and have one or multiple frequency band-gaps in
which no substrate mode can exist. This unique ownership
has been utilized to design antenna systems with a improve
gain and efficiency, lower side-lobes and back-lobe levels
amend isolations within array elements, by crushing surface
wave modes [2–4]. The EBG substrate has been utilized to
alleviate some withdraws of conventional microstrip
antennas [5–7]. Recently, radiation features of a microstrip
patch over a mushroom-type electromagnetic band-gap
(EBG) substrate were inquired [9]. The EBG surface e is
found to have the impressions of diluting the patch resonant
length and bandwidth as a result of stronger capacitive
coupling.
In this paper, the functioning of a rectangular microstrip
patch antenna has been mended utilizing a new cylindrical
electromagnetic band-gap (EBG) substrate. The patch
antenna is fed by a driven terminal and is integrated within a
cylindrical electromagnetic band-gap substrate, based on the
mushroom-like substrate, to raise the antenna gain and
bandwidth. The cylindrical electromagnetic band-gap
structure applied is a combination of two periodic structures
with dissimilar periods. The feature of the patch antenna
based on drilling air holes and embedding a metal boundary
in the substrate were studied by [9]. The outcome suggested
that the surface waves which spread along the surface of the
substrate can be inhibited by the multiple photonic band-gap
structure because of its consequences of forbidden band, that
it can diversify almost of electromagnetic waves’ energy in
the substrate importantly, and that it has lower return loss
(S11) compared to the conventional patch antennas and
enhanced gain.
2. ELECTROMAGNETIC BAND-GAP
STRUCTURE
Periodic structures are ample in cosmos beguiled artists and
scientists alike. When an electromagnetic waves energizing
procedures amazing boa
Fig 1: Electromagnetic band-gap fundamental structure
showing radius and periodicity of structure
In detail, boats frequency stop-bands, pass-bands, and band
identified [1]. Brushing up the literature, on several
nomenclatures have been applied looking of the
applications. These applications are innovation, gratings,
frequency exclusive surface photonic crystals [2] and
photonic band-gaps They can be assorted beneath the liberal
Electromagnetic Band-gap (EBG) structures in General
speaking, electromagnetic banish are specified as unreal
periodic (or formerly objects that forbid/aid the propagation
of waves in a assigned band of frequency for al and all
polarization states (as shown in F structures are commonly
recognized by periodic dielectric materials and metallic
conductors (as shown in fig. 1). In universal, they can be
categorized in allowing to their geometric configuration: (1)
dimensional volumetric structures, (2) two-dimensional
surfaces, and (3) one-dimensional.
3. ANALYSIS AND DESIGN
In this division, a rectangular microstrip patch antenna and
its cylindrical EBG substrate are projected by applying a
Finite Element method (HFSS-Ansoft). In the pretense
operation convergence and minimization of numerical errors
were received by assuring that the mesh was sufficiently
alright. In Subsection A, the patch antenna is planned to
function at an arbitrary chosen frequency. Then, in
Subsection B, the EBG substrate is projected to enhance the
gain of the patch antenna at its functioning frequency.
3.1 Rectangular microstrip patch antenna
This subsection identifies the patch-antenna configuration
that is chose to execute the comparison between using a
normal substrate and a cylindrical EBG substrate. The
antenna is depicted in Fig. 2. The patch antenna is
rectangular with length of l = 15.8 mm and breath is b =
8mm printed on a substrate with a relative permittivity of or
= 2.2. The patch is fed by a probe and placed 6 mm from the
center of the patch. The feed location was optimized to
afford better impedance matching. The sizing of the
substrate is 180 mm × 180 mm. The antenna resonates at
10.667 GHz.
Fig 2: Rectangular patch antenna with microstrip.

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The maximum gain of the patch antenna is about 6 dB. The
gain of this antenna is heightening using a cylindrical EBG
substrate, which is depicted in the next subsection.
3.2 Patch antenna surrounded by a cylindrical
EBG substrate
While the previous subsection has defined the patch-antenna
configuration, the design of the EBG substrate is now
presented. Figure 3 shows the schematic of the proposed
patch antenna surrounded by a cylindrical structure
composed of metal rings and grounding vias. The concentric
rings of strips are etched on the same plane than the patch
antenna, with the distance 5mm from one to another. The
first metal ring starts at the radius 2mm.
Fig 3: Patch incorporated with the cylindrical EBG
substrate.
The vias have the radius a, and they are disposed with the
same transversal period Pt and the same radial period
Pr2.The following parameters are fixed: 2a = g = 2mm. The
remaining parameters Pr1 and Pr2 were optimized. Three
concentric rings and three circularly periodic structures of
vias are considered. According to numerical results (not
shown here), the gain is not sufficiently increased when only
one or two layers are used.
4. SIMULATION RESULT
The proposed EBG-based antenna structure has been
simulated using cell size 129 × 131 × 34. Here, time step ∆t
= 2.0747 ns. Results have been analyzed for variation of
bandwidth, active z parameter, vswr, gain and reflection loss
because EBG structures are expected to increase bandwidth
and gain by suppression of surface waves. fig.5 shows active
z parameter got from the designed EBG structure. fig.4
shows bandwidth obtained for the proposed structure on
rectangular patch. The vswr of the proposed design is shown
in Fig.6.
Fig 4: Z Parameter vs. frequency (in GHz) for the proposed
structure.
Fig 5: Z Bandwidth vs. frequency (in GHz) for the proposed
structure.
Fig 6: VSWR (in dB) vs. frequency (in GHz) for the proposed
structure.

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5. OBSERVATIONS
Observations concerning the bandwidth, active z
parameters, active vswr, and gain and reflection loss using
the proposed antenna structure have been talked about and
amended in this section.
5.1 BANDWIDTH
This design achieved an impedance bandwidth of 10.14%
(2.34-2.59 GHz) at -10 dB return loss. Simulated radiation
pattern is almost omnidirectional. The simulated results
prove the compatibility of the EBG antenna with the 2.46
GHz ISM band applications. Further enhancement of the
antenna performance with improved design is under
consideration.
6.2 Gain
Gain has been accounted from the radiation patterns in E
and H-plane for the patch antenna. Gain receive from
proposed antenna structure (EBG substrate) is found to be
7.7324 dB at 10.667 GHz (from Fig. 5-6). Gain receive from
patch without any EBG structures show a value of 6 dB at
an operating frequency of 10.667 GHz. Gain obtained using
proposed structure is importantly more than that without
EBG.
6.3 Reflection loss
Reflection loss for aimed EBG-substrate patch is found to
attain a lowest value of -33 dB. It is evident from the
reflection loss curves of the antenna structures using EBG
and that without EBG that reflection loss has reduced
drastically for patch with EBG. This has ensued in a
noteworthy improvement in gain. The bandwidth of the
constitute EBG-based patch is bumped to be 112.3 MHz.
6. DISCUSSION
It is known that the bandwidth of the antenna can be
enhanced by contracting any loss of the antenna. Selection
of an effective quality (low-loss) substrate will contract the
dielectric and conductor losses. However, surface waves go
inside the substrate and reduce the bandwidth. To reduce
this surface wave loss, wave propagation has to be stopped
inside or reflected outside the substrate to enhance the
bandwidth in forward direction. The waves are arrested or
retarded by obstructing their path with a high propagation-
impedance - air (εr =1). The impedance offered by a
dielectric is given as ή/ . This implies that the
impedance offered, is maximum for smallest value of εr (the
smallest value of εr being 1 for air). In the proposed
antenna, the surface waves are reduced by drilling holes in
periodic fashion in the dielectric substrate. The remarkable
improvement in gain can be attributed to the periodic effect
of embedding air voids (holes) in the substrate.
7. CONCLUSION
In this paper, a novel proficiency for the bandwidth
sweetening of micro-strip patch antennas using a cylindrical
EBG structure has been aimed and established. The EBG
structure is based on the mushroom-like structure with a
circular proportion. It is framed of a periodic structure of
metallic rings and of a periodic structure of vias. The
periods of time of these structures have been optimized
applying a full-wave method to maximize the bandwidth.
The new substrate comes down the surface wave, but the
bandwidth enhancement is primarily due to the coupling
between the patch and the EBG structure.
8. REFERENCES
[1] Gautheir, G. P., A. Courtay, and G. M. Rebiez, Microstrip
antennas on synthesized low dielectric constant substrate,"
IEEE Trans. Ant. Propag., 1997.
[2] Papalymerou, I., R. F. Drayton, and L. P. B. Katehi,
Micromachined patch antennas," IEEE
[3] Qian, Y., R. Coccioli, D. Sievenpiper, V. Radisic, E.
Yablonovich, and T. Itoh, Microstrip patch antenna using
novel photonic bandgap structures," Microw. J., Vol. 42,
No. 1, 66{76, 1999.
[4] M. Khayat, J. T. Williams, D. R. Jakson, and S. A. Long,
“Mutual coupling between reduced surface-wave microstrip
antennas, IEEE Trans. Antennas Propag., vol.48, pp. 1581-
1593, Oct. 2000.
[5] D.M. Kokotoff, R.B. Waterhouse, C.R. Britcher, and J.T.
Aberle, “Anular ring coupled circular patch with enhanced
performance”, Electron. Letters, vol.33, pp. 2000-2001,
Nov. 1997.
[6] Agi, K., K. J. Maloy, E. Schmiloglu, M. Mojahedi, and E.
Niver, Integration of a microstrip
patch antenna with a two-dimentional photonic crystal
substrate," Electromagnetics, Vol. 19, 277{290, May{Jun.
1999.
[7] A. K. Bhattacharayya, “Characteristics of space and surface-
waves in a multilayered structure”, IEEE Trans. Antennas
Propag., vol.38, pp. 1231- 1238, Aug. 1990..
[8] J. Joannopoulos, R. D. Meade and J. N. Winn, Photonic
crystals: molding the ﬂow of light, Princeton University
Press, 1995M.
[9] R. Gonzalo, P. de Maagt, and M. Sorolla, “Enhanced path-
antenna performance by supresing surface waves using
photonic-bandgap substrates”, IEEE Tran. Microw. Theo.
Techn., vol. 47, pp. 2131-2138, Nov. 1999.
[10]D. Sievenpiper, L. Zhang, R.F. Jimenez Broas, N. G.
Alexopoulos, and E. Yablonovitch, “High-impedance
electromagnetic surfaces with a forbidden frequency band”,
IEEE Trans. Microwave Theory Techn., vol. 47, pp. 2059-
2074, Nov. 1999.
[11]Y.-J. Park, A. Herchlein, and W. Wiesbeck, “A Photonic
Bandgap (PBG) structure for guiding and suppressing
surface waves in millimeter-wave antennas”, IEEE Trans.
Antennas Propagat., vol. 49, pp. 1854-1857, Oct. 2001.
[12]K. Agi, M. Mojahedi, B. Minhas, E. Schamilogu, and K. J.
Malloy, “The effects of an electromagnetic crystal substrate

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on a microstrip patch antenna”, IEEE Trans. Antennas
Propag., vol. 50, pp. 451-456, April 2002.
[13]F. Yang and Y. Rahmat-Samii, “Microstrip antennas
integrated with electromagnetic bandgap (EBG) structures: a
low mutual coupling design for array applications”, IEEE
Trans. Antennas Propag., vol. 51, pp. 2936-2946, oct. 2003.
[14]N. Llombart, A. Neto, G. Gerini, and P. de Maagt, “Planar
circularly symettric EBG structures for reducing surface
waves in printed antennas”, IEEE Trans. Antennas Propag.,
vol. 53, pp. 3210-3218, Oct. 2005.
[15]A. Neto, N. Llombart, G. Gerini, and P. de Maagt, “On the
optimal radiation bandwidth of printed slot antennas
surrounded by EBGs”, IEEE Trans. Antennas Propag., vol.
543, pp. 1074-1083, Ap. 2006.
BIOGRAPHIES
Gaurav Kumar Sharma, he is
M.Tech (ECE) student at Amritsar
college of Engineering &
technology, AMRITSAR. He has
earlier completed her B.Tech in
ECE from ACET, Amritsar. His
area of interest are Antenna &
Wave Propagation, Antenna
designing and fabrication, Signal
Processing, and optical fiber
communication. Email id:
gaurav.bhanot@yahoo.com
Narinder Sharma, he is working as
HOD of EEE at Amritsar College
of Engineering and Technology. He
is B.Tech, M.Tech, and Qualified.
He has attended many international
and National conferences and have
Published Paper in national and
International Journals

Improving the performance parameters of microstrip

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