A Miniaturized Multiband Monopole Antenna With CSRR Loaded on Ground plane

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A Miniaturized Multiband Monopole Antenna With
CSRR Loaded on Ground plane
Ahmed El Yousfi∗, Abdenacer Es-salhi∗, Abdenasser Lamkaddem∗, Daniel Segovia-Vargas†, M.A.Ennasar‡andO. El Mrabet§
∗Departement of physics
Mohamed I University, Oujda, Morocco
Email:ahmed.elyousfi19@gmail.com
†Signal Theory and communications Departement, Universidad Carlos III de Madrid, Madrid, Spain
Email: dani@tsc.uc3m.es
‡Mohamed V university, Rabat, Morocco
§Abdelmalak Esaasdi University, Tetuan, Morocco
Abstract—This paper presents a compact multiband planar
antenna based on the inclusion of complementary split ring
resonators (CSRR) in the ground plane. The antenna is composed
of an inverted L monopole, that presents a 30% reduction length
with respect to the conventional one, and a partial ground
plane in which the CSRRs are etched to generate the multiband
characteristic. First, two equal radius CSRRs are etched in the
ground plane and excited by a meandered microstrip feed line.
As a result a broad dual band frequency. Secondly, a stub feed
is introduced to create a triple band by making the CSRRs’s
radius different. For both cases simulations and measurements
show good agreement. .
I. INTRODUCTION
Recently, a considerable interest has been devoted to meta-
materials because of their exotic electromagnetic character-
istics for improving antenna performances (miniaturization,
impedance matching. . . ). SRRs and CSRRs (dual particle of
SRR) are some of the most common elements exploited in an-
tenna design for achieving multiband operation [1]-[3]. How-
ever, the reported designs suffer from narrow bandwidth or low
efficiency. In this paper, by etching CSRRs in the ground plane
of a monopole antenna and exciting them properly, dual-broad
band and triple-band performance are obtained. The CSRRs
are electromagnetically coupled to the microstrip feed line
providing the monopole resonance remains unchanged. Indeed,
independent control of the operating frequency bands can be
achieved. The organization of this paper is as follows. In
section II, antenna design is presented. The section III provides
results and their discussions. Section IV contains conclusions.
II. AN TE NNA DESIGN
A. Dual braodband antenna design
The proposed compact dual broadband antenna is depicted
in Fig 1. It is composed of an inverted L monopole printed
on a thin Roger substrate of permittivity r=0.787, los tangent
δtan= 0.0009 and thickness h=0.787mm.In the opposite side
of the substrate, located the ground plane, two symmetrical
CSRRs have been inserted to achieve dual band performance.
A meandered feeding is used to excite the CSRRs and provide
50 Ωimpedance matching.It is important to note that this
configuration provides broadband and multiband performance
with via-free unit cell in contrast to [4], which simplifies the
manufacturing process and decreases the costs. The dimen-
sions of CSRRs are calculated based on [5]..
Fig. 1: Proposed broadband antenna and its dimensiosns in
mm (a) top view (b) bottom view.
B. Triple band antenna design
The configuration of the proposed triple band monopole
loaded with CSRRs is illustrated in Fig 2. The monopole’s
dimensions are kept unchanged, whereas the CSRRs dimen-
sions are varied to attain multiband performance. The feed
line is modified to provide equal amplitude and in phase
power to overcome the tilted beam radiation introduced by
the meandered feed line in the previous proposed design.
III. RES ULTS A ND DISCUSIONS
Based on the simulation results, two prototypes were fab-
ricated and measured. Fig 3 and 4 show the simulated and
measured reflection coefficient of the dual broad band and
triple band CSRR loaded monopole antenna. The simulated
(measured) bandwidth of the proposed dual broad band an-
tenna is of about 16% (6.4%) and 27%( 23.6%) in the
lower and higher band respectively. The simulated (measured)
bandwidth of the proposed triple band antenna is of about 10%
(10.4%) , 2.4%(2.5%) and 21% (20%) in the three bands. We
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2020 IEEE International Symposium on Antennas and Propagation and North American Radio Science Meeting | 978-1-7281-6670-4/20/$31.00 ©2020 IEEE | DOI: 10.1109/IEEECONF35879.2020.9329929
Authorized licensed use limited to: UNIVERSIDAD CARLOS III MADRID. Downloaded on May 04,2021 at 13:53:18 UTC from IEEE Xplore. Restrictions apply.

Fig. 2: Proposed triple BAND antenna and its dimensiosns in
mm (a) top view (b) bottom view.
note that, for both designs, the first resonance corresponds to
the monopole and the others correspond to the CSRRs. The
observed discrepancy is due to the conditions of measurement
and fabrication errors. The simulated radiation pattern of the
Fig. 3: Simulated and measured S11 of the proposed dual
broadband antenna.
Fig. 4: Simulated and measured S11 of the proposed triple
band antenna.
two proposed designs is shown in Fig 5 and 6. It is seen that
Fig. 5: Simulated radiation pattern of the proposed dual
broadband antennna at (a)2.45 GHz and (b)5.8 GHz..
the dual broadband antenna provides a dipole like radiation
pattern with a disturbed radiation in the higher band. Similar
behavior is obtained for the triple band antenna. The simulated
Fig. 6: Simulated radiation pattern of the proposed triple band
antennna at (a) 2.4 GHz, (b) 3.6 GHz and 5.8 GHz.
gain (efficiency) of the proposed dual broad band design is of
about 1dB (75%) within the lower frequency band while in the
higher frequency band it drops down (5.5 dB-0.5 dB) due to
the antiphase current flowing in the meandered feed, however
the efficiency achieves more than 85% in the whole operational
band. For the triple band antenna, the gain (efficiency) reach
1.7 dB (98%), 1.3 (80%) and 4 dB (97%) in the whole three
bands.
IV. CONCLUSION
Two different compact multiband antenna designs are pre-
sented in this paper. Good results are achieved in terms of
bandwidth, gain, efficiency and radiation pattern for both
topologies. Altering the CSRRs dimensions allow an indepen-
dent tune of the operating frequency bands, which implies that
any desired frequency ratio can be obtained.
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