This document discusses the design of a metamaterial structure to enhance the performance of a rectangular microstrip patch antenna. It first describes the design of a basic rectangular microstrip patch antenna. It then proposes a hexagonal shaped metamaterial structure placed above the antenna to act as a substrate. Simulation results show that with the metamaterial structure, the antenna gains improved directivity, main lobe direction, and radiation efficiency while still exhibiting negative permeability and permittivity. The metamaterial structure enhances the antenna performance.

1. International Journal of Electronics and Communication Engineering & Technology (IJECET),
INTERNATIONAL JOURNAL OF ELECTRONICS AND
ISSN 0976 – 6464(Print), ISSN 0976 – 6472(Online), Special Issue (November, 2013), © IAEME
COMMUNICATION ENGINEERING & TECHNOLOGY (IJECET)
ISSN 0976 – 6464(Print)
ISSN 0976 – 6472(Online)
Special Issue (November, 2013), pp. 60-65
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IJECET
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Design of a New Metamaterial Structure to Enhancement the
Performance of Rectangular Microstrip Patch Antenna
Baljeet Singh Sinwar1, Dr. Mithilesh Kumar2
Electronics Eng. Department, UCE, Rajasthan Technical University, Kota-302010
1singh.baljeet27@yahoo.co.in, 2mith_kr@yahoo.com.
ABSTRACT: In this paper, a hexagonal shaped structure has been chosen to contruct
metamaterial substrate. This hexagonal shaped structure enhances the performance of a
rectangular microstrip patch antenna. This metamaterial structure is proposed at a height of
3.2mm from the ground plane. For verifying that the proposed metamaterial structure
possesses Negtive values of Permeability and Permittivity within the operating frequency
ranges, Nicolson-Ross-Weir method (NRW) has been employed. The patch along with the
proposed metamaterial structure is designed using CST-MWS software and compares the
results.
KEYWORDS: Nicolson-Ross-Weir method (NRW), Rectangular Microstrip patch antenna
(RMPA), Return Loss
I.
INTRODUCTION
Microstrip Patch Antennas generally have three components namely ground, substrate, patch.
These are low profile, lightweight, low cost antennas. These antennas have some drawback like
narrow-bandwidth, low gain etc. Several researches have been done to overcome these
drawbacks. In this field of research, Victor Veselago (1968) Engheta and Ziolkowski (2006)
introduced the theoretical concept of metamaterials. According to the theory of Vesalago, these
materials are generally artificial materials used to provide properties which are not found in
readily available materials in nature [1]-[2]. And they have Negtive Refractive Index (NRI),
hence they are also called as the Negative Refractive Index materials or Left handed materials
LHM (as they follow left hand rule) [3]-[5]. In this work “Hexagonal shaped structure” as a
metamaterial structure has been introduced for enhancement the patch antenna parameters.
With these improvements this hexagonal structure also possesses double negative properties
within the operating frequency ranges.
II.
ANTENNA DESIGN AND METHODOLOGY
The Rectangular microstrip patch antenna parameters are calculated from the formulas given
below.
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B K Birla Institute of Engineering & Technology (BKBIET), Pilani, India
October 18-20, 2013
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2. International Journal of Electronics and Communication Engineering & Technology (IJECET),
ISSN 0976 – 6464(Print), ISSN 0976 – 6472(Online), Special Issue (November, 2013), © IAEME
Desired Parametric Analysis:
Calculation of Width (W),
W=
=
μ
(1)
Where,
c = free space velocity of light;
εr = Dielectric constant of substrate.
Effective dielectric constant is calculated as,
ε
=
+
(2)
h
The actual length of the Patch (L),
L = Leff - 2ΔL
(3)
Where,
Leff =
(4)
Calculation of Length Extension,
∆
h
= 0.412
(
. )
(
.
.
h
)
h
(5)
.
The RMPA (in Fig. 1) is designed using the calculated parameters shown below in Table 1.
Dimensions
Dielectric Constant (εr)
Loss Tangent (tan δ)
Thickness (h)
Operating Frequency
Length (L)
Width (W)
Cut Width
Cut Depth
Path Length
Width Of Feed
4.3
0.02
1.6
2.478,2.919
23.69
30.71
4.28
10.0
25.357
2.8
Table 1: RMPA Specifications
Unit
mm
GHz
mm
mm
mm
mm
mm
mm
Dimensional view of a rectangular microstrip patch antenna is shown in figure1. Dimensional
view of a metamaterial structure is shown in above figure 2. In this structure the dimension of
centered rectangular structure is 4×3mm.
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B K Birla Institute of Engineering & Technology (BKBIET), Pilani, India
October 18-20, 2013
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3. International Journal of Electronics and Communication Engineering & Technology (IJECET),
ISSN 0976 – 6464(Print), ISSN 0976 – 6472(Online), Special Issue (November, 2013), © IAEME
To calculate the S-parameters, the proposed structure of metamaterial is placed between the
two waveguide ports [6], [7] at the left and right hand side of X axis. In Fig. 3, Y-plane is defined
as Perfect Electric Boundary (PEB) and Z-plane is defined as the Perfect Magnetic Boundary
(PMB) to create internal environment of waveguide. Subsequently, the wave was excited from
the negative X-axis (Port 1) towards the positive X-axis (Port 2).
Through this arrangement, the S parameters were obtained in complex form, which are then
exported to Microsoft Excel program for verifying the double-negative metamaterial properties
of the proposed metamaterial structure by using the NRW approach.
Formulas for calculating the value of permittivity & permeability using NRW approach [8][10]:
r 
2 .c . 1  v 1 
w . d .i .(1  v 2 )
(6)
15.357
30.71
2.8
4.28
10
23.69
Fig.1: Rectangular patch antenna
17
11
5
Fig. 2: Proposed meta structure
Fig. 3: Proposed metamaterial cover placed between the two Waveguide Ports
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4. International Journal of Electronics and Communication Engineering & Technology (IJECET),
ISSN 0976 – 6464(Print), ISSN 0976 – 6472(Online), Special Issue (November, 2013), © IAEME
 r  r 
Where,
V1 = S11 + S21
2.s11.c.i
w.d
(7)
V2 = S21 – S11
Where,
ω = Frequency in Radian, d = Thickness of the Substrate ,c = Speed of Light,V1 = Voltage
Maxima & V2 = Voltage Minima.
III.
SIMULATION AND RESULTS
The values of permittivity (ε) and permeability (µ) are calculated by using (6) and (7) in the
simulated frequency range. Graph in figures 4(a) and 4(b) shows that the proposed
metamaterial cover possesses negative values of permittivity & permeability at the resonating
frequency.
Fig. 4: (a) Permeability versus Frequency Graph (b) Permittivity versus Frequency Graph
The obtained values of permeability within frequency ranges are given in Table 2 and obtained
values of permeability within frequency ranges are given in Table 3.
Frq[GHz]
Permeability[μr]
Re[μr]
2.50
-37.0156377595638-19.348541095219i
-37.01564
2.50
-36.5356387155859-19.2237456316763i -36.53564
2.50
-36.0616612486426-19.1020068912619i -36.06166
2.51
-35.5934749420146-18.9832430952429i -35.59347
2.51
-35.1310955048797-18.8673992385962i -35.13110
Table 2: Obtained values of permeability from Excel program
Freq[GHz]
Permittivity[εr]
Re[εr]
2.50
-42.5173256091449-10.4139931114566i
-42.51733
2.50
-42.0114436385906-10.3240307338169i
-42.01144
2.50
-41.512661109927-10.237130826588i
-41.51266
2.51
-41.0207460913582-10.1531922835657i
-41.02075
2.51
-40.5357113292545-10.0721436654276i -40.53571
Table 3: Obtained values of permeability from Excel program
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5. International Journal of Electronics and Communication Engineering & Technology (IJECET),
ISSN 0976 – 6464(Print), ISSN 0976 – 6472(Online), Special Issue (November, 2013), © IAEME
Above tables obtained from MS-Excel program. To obtain these values first of all we extract the
S-parameters from the proposed metamaterial structure and then use NRW technique. This
technique provides easy as well as effective formulation and calculation.
Fig.5: Rectangular patch antenna with metamaterial structure
Fig.6: S11 of a RMPA with and without metamaterial structure
(a)
(b)
Fig. 7: Radiation pattern of RMPA (a) with proposed metamaterial structure (b) without
metamaterial structure
The comparison among different parameters of a rectangular microstrip patch antenna with
and without metamaterial are shown in Table 4. And it shows that metamaterial improves the
performance of a rectangular microstrip patch antenna.
Without meta
With meta
Main Lobe Direction
1.8 dBi
12.2 dBi
Rad. Effi.
.3455
.7957
Tot. effi.
.5674
.008328
Directivity
2.134 dBi
12.94 dBi
Side lobe level
-14.3 db
-13.2 db
Angular width[3 dB]
92.7 deg.
94.9 deg.
Table 4: Comparison between with or without meta sturcture
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6. International Journal of Electronics and Communication Engineering & Technology (IJECET),
ISSN 0976 – 6464(Print), ISSN 0976 – 6472(Online), Special Issue (November, 2013), © IAEME
The radiation pattern and table 4 show that the directivity with and without metamaterial is
12.94dbi and 2.134dBi, respectively. These results are showing that there is improvement in
directivity of RMPA by incorporating proposed metamaterial structure.
IV.
CONCLUSION
On the basis of simulation results it is observed that the directivity has been improved
significantly by incorporating the proposed metamaterial structure at 3.2 mm height from
ground plane of the antenna. Along with these improvements this structure improves the main
lobe direction and also satisfies Double Negative property within the simulated frequency
range.
REFERENCES
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[3]. D. R. Smith, W. J. Padilla, D. C. Vier, S. C. Nemat-Nasser, and S. Schultz. “Composite medium
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BIOGRAPHY
Baljeet Singh Sinwar was born in Hanumangarh, Rajasthan, India in 1990.
He received the B.Tech degree in Electronics and Telecommunication
Engineering from Sri balaji College of Engg and Tech. (Jaipur), India in 2010.
He is pursuing his M. Tech in Digital Communication at University College of
Engg., Rajasthan Technical University (RTU), Kota, India. His current
research interests focus on Antenna and Microwave Engineering.
International Conference on Communication Systems (ICCS-2013)
B K Birla Institute of Engineering & Technology (BKBIET), Pilani, India
October 18-20, 2013
Page 65