Planar monopole antenna with offset square split
ring resonator
Murtala Aminu-Baba1, Mohammad Kamal A Rahim1, Farid Zubir1, Mohd Fairus Mohd Yusoff1, 1Osman Ayop, Noor Asmawati Samsuri1
1Advanced RF & Microwave Research Group,
School of Electrical Engineering Universiti Teknologi Malaysia, (UTM), 81300 Skudai, Johor Bahru, Malaysia Corresponding author, e-mail: [email protected]; [email protected]; [email protected]; [email protected],
Abstract – A low cost, low profile dual band metamaterial
monopole antenna is proposed in this paper. These bands are achieved when a Square Split Ring Resonator (S-SRR) is added on the ground plane; a narrow band covering WiMAX and standard ultrawideband (UWB) with a patch antenna dimension of 10.17 x 15 mm2. In order to realize the bandwidth enhancement, parametric studies of the S-SRR and gaps position were performed. The antenna design was performed on the low cost FR4 substrate using CST Microwave Studio. The proposed antenna is suitable for UWB systems covering WLAN/WiMAX for high data rate, interference mitigation and signal quality improvement.
Index Terms — Monopole antennas, S-SRR, UWB.
1. Introduction
Due to the recent development in the wireless and
communication technology, various communication system
can operate in more than one frequency band such as
wireless LANs (WLANs), WiMAX, satellite navigation
systems, ultrawide-band (UWB) or combination of them, [1-
3]. Thus, a single antenna with compact size that has the
capcity to cover multiple bands is required for limited space
environment. Among the numerous advantages of UWB
antennas such as strong protection to multipath fading, high
data rate, low interference and high channel capacity, great
research interests have aroused in the last few decades.
Various types of UWB antennas have been reported in [4-8].
Monopole antennas as reported in [8] have been widely used
due to their low profile, low cost and ease of fabrication.
Moreover, different techniques have been used to improve
the bandwidth of the monopole antenna, include the feed,
radiator or ground modification [1], [9], applying fractal
elements to the patch [8], and by the introduction of
metamaterial structure [10]. The authors in [10] presented an
UWB monopole antenna with flexible AMC for gain
bandwidth enhancement. However, the design approach is
quite complex as it requires extra circuitries for
implementation.
In this paper, a simple technique using metamaterial
structure is proposed for bandwidth enhancement, gain
improvement and additional band generation. Fig. 1 shows
the rectangular monopole antenna microstrip line with the
SRR on the back plane fed by a 50 Ω.
2. Antenna Design and Simulation
(i) Monopole Antenna
Fig. 1. shows the structure of the proposed antenna with
the labeled designed parameters. The monopole antenna is
comprised of a microstrip feed structure and rectangular
radiator with partial ground plane. The antenna is designed
and simulated using CST Microwave Studio and printed on
FR4 substrate with a thickness of 0.8 mm and permitivity of
4.4. The layout of the structure and the parameters are shown
in Fig. 1. Fig. 2 depicts the reflection coefficient of the
monopole antenna.
top view Bottom view
Fig. 1 Structure of the proposed metamaterial monopole antenna geometry. L
= W= 43mm, hf = 15.9, Lp = 15, Wp = 10.17, Zo = 4, g = 0.5, Z = 1, j = 7.2, f
= 6.15
Fig. 2. Simulated results for the proosed metamaterial antenna reflection
coefficent, with and without R-SRR.
2018 International Symposium on Antennas and Propagation (ISAP 2018)October 23~26, 2018 / Paradise Hotel Busan, Busan, Korea
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(ii) Monopole Antenna with R-SRR
It can be seen in fig. 2 that, by addition of the SRR on the
ground plane of the monopole antenna, the impedance
bandwidth is improved from (3.1303 ~ 4.5748) – (9.49 ~
13.6520) to an UWB (3.1414 ~ 13.2180) and also generates
additional narrowband of (2.5627 ~ 2.7597). The first and
second resonant frequencies of the monopole antenna are
shifted to higher and upper and lower frequencies from 3.66
~ 9.61 GHz respectively, thereby leading to a bandwidth
from (3.1414 ~ 13.2180) GHz. Thus, it can be concluded that
SRR additional band and improve a wideband that results in
an UWB bandwidth.
3. Results and Discussion
The simulated reflection coefficient for the proposed
antenna with and without the SRR are shown in Fig. 2. It can
be compared and verified that the use of SRR improves the
impedance bandwidth and creates additional band. Based on
the presented results in terms of the operating frequency,
bandwidth and antenna gain are shown in table I. Fig. 3
shows the 3D radiation pattern of the antenna at various
frequencies. Monopole antenna with SRR has a better gain at
the higher than the simple monopole antenna.
TABLE I
Simulated 10-dB band antenna performance for the proposed
metamaterial monopole antenna
(a) (b)
(c) (d)
(e) (f)
Fig. 3. The far field of the monopole antenna with SRR at (a) 2.67 (b)3.50 (c)
3.89 (d) 5.50 (e) 8.20 (f) 10.4 GHz
4. Conclusion
In this paper, a dual band metamaterial monopole antenna
has been presented for WiMAX and standard UWB
applications. The impedance bandwidth of the monopole
antenna is greatly improved from wide bands (3.1303 ~
4.5748) – (9.49 ~ 13.6520) to an UWB (3.1414 ~ 13.2180)
and also generates additional narrowband of (2.5627 ~
2.7597) by loading a SRR in the ground plane. Moreover,
high gain, good radiation characteristics and matching were
obtained at the respective frequencies.
Acknowledgment
The authors would like to thank the Ministry of Higher Education (MOHE)
for supporting the research work, Research Management Centre (RMC),
School of Electrical Engineering, Universiti Teknologi Malaysia (UTM) for
the support of the research under grant no. 14J87, 04G69 and 16H08.
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Antenna
Type
Antenna Performance
Frequency
(GHz) Bandwidth
Antenna
Gain (dB)
Monopole
Antenna
3.65 1.44 GHz (3.1303 ~ 4.5748) 2.15
12.4 4.162 GHz (9.49 ~ 13.6520) 4.96
Monopole
with
CSRR
2.67 197 MHz (2.5627 ~ 2.7597) 1.90
3.50
10.08 GHz (3.1414 ~ 13.2180)
2.18
3.89 2.31
5.50 4.12
8.20 3.56
10.4 5.25
2018 International Symposium on Antennas and Propagation (ISAP 2018)October 23~26, 2018 / Paradise Hotel Busan, Busan, Korea
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