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Simulation of Crumpling in Integrated EBG Textile CPW Fed
Monopole Antenna
A. Alemaryeen and S. Noghanian
Department of Electrical EngineeringUniversity of North Dakota,
Grand Forks, ND 58202-7165, USA
[email protected], [email protected]
Abstract Performance of a textile monopole
antenna after integration on a flexibleElectromagnetic Band Gap
(EBG) surface under
crumpling conditions has been investigated at 2.45
GHz. Matching performance and antenna gainremains robust in many
crumpling cases.
Index Terms Coplanar Waveguide (CPW),
Electromagnetic Bandgap Structure (EBG),Monopole Antenna,
Wearable Antenna.
I. INTRODUCTIONIn recent years, intelligent garments
equipped
with wireless communication and other devices
have been used in different applications such as insports,
military domains and fire fighting, in order
to provide information about the wearers healthand environmental
states.
As a result of the antenna working in close
proximity to human body in wearable antennaapplications,
frequency-detuning problem mightarise because of the high
dielectric properties of thehuman body. Besides, reducing the back
radiationfrom the antenna is a challenging problem in body
worn context. EBGs have been widely investigateddue to the
potential advantage of eliminating thedetuning effects and
directing the electromagneticwave in the desired direction of
propagation [1].
In this paper, we provide results from a studyof CPW fed
monopole textile antenna integrated ona flexible EBG surface. In
addition, because of the
difficulty to keep the garment surface in a certainform, and
consequently the wearable antenna willnot stay in flat shape, it is
necessary to study the
performance of the antenna under differentcrumpling conditions.
Simulations have been
carried out in CST Microwave Studio software.
II. ANTENNA AND EBG STRUCTURESConfiguration of CPW monopole
antenna and
EBG cell was originally outlined in [2-3]. Pellonfabric has a
thickness of 3.6 mm and relative
dielectric constant of 1.08 is used as a substratematerial of
the antenna. Structure and dimensionsof monopole antenna are shown
in Fig. 1. FlexibleRO3003 material of relative dielectric constant
3and thickness 1.52 mm is used in the EBG design.
Figure. 2 shows geometry and dimensions of a unitcell model.
Fig. 1. Dimensions details given in mm and
geometry of CPW monopole antenna.
III. ANTENNA PERFORMNACE UNDER
CRUMPLING CONDTIONSIn practical situations, many crumpling
forms
may take place. Textile antenna performance is
studied for three types of crumpling chosen forinvestigation in
this research for the antenna placedon the chest and the back of
the wearer.
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Crumpling profile is defined by: crumple depth h,and crumple
periodL, as shown in Fig. 3. A central
part of antenna of 0.5 mm is kept flat for the
feedingrequirements.
Fig. 2. EBG unit cell structure, dimensions aregiven in mm.
Fig. 3. Crumpling profile details.
Summarized results are presented in Table 1,
where the variation of L and h are given in mm.Acceptable
frequency range is defined as -10dBreflection coefficient (S11). A
shift in range of MHzis shown for the lower (fl) and upper (fh)
frequency
band. S11and antenna gain are obtained at 2.45 GHz
for crumpled antenna compared with the flat
antenna.Monopole antenna with EBG backing
measured 124 mm 124 mm was crumpled asshown in Fig. 3. Crumpling
profile of 6 mm depth
and 31 mm period of crumple is chosen forinvestigation. Table 2
compares results of antenna
with EBG in both flat and crumpled situations.Results show a
reduction in the bandwidth and
enhancement in the gain using EBG structure
compared with the antenna alone and a shift in theresonance
frequencyfrafter crumpling process.
Table 1: Simulated return loss and gain summary at2.45 GHz for
textile monopole antenna underdifferent crumpling conditions
Table 2: Simulated gain summary of both flat andcrumpled
monopole antenna with EBG
IV. CONCLUSIONGain of a textile monopole antenna under
crumpling conditions might be substantiallydegraded, while the
shifts in frequency
performance is still acceptable. Various cases willbe presented
at the conference.
REFERENCES
[1]
S. Velan, E. Sundarsingh, M. Kanagasabai, A.
Sharma, C. Raviteja, and R. Sivasamy, Dual-band
EBG integrated monopole antenna deploying fractal
geometry for wearable applications, IEEE
Antennas and Wireless Propagation Letters,Early
access article, DOI: 10.1109/LAWP.2014.2360710,
2014.
[2] M. Mantash, A.-C. Tarot, S. Collardey, and K.
Mahdjoubi, Investigation of flexible textile
antennas and AMC reflectors, International
Journal of Antennas and Propagation, vol. 2012,
article ID 236505, 10 pages,
http://dx.doi.org/10.1155/2012/236505.
[3]
J. R. Sohn, H. S. Tae, J.-G. Lee, and J.-H. Lee,
Comparative analysis of four types of high-
impedance surfaces for low profile antenna
applications, IEEEInternational Symposium on
Antennas and Propagation, vol. 1A, pp. 758-761,
Washington DC., July 2005.
Parameter FlatL=31h=11
L=24h=6
L=31h=6
fl(GHz) 1.76 2.31 2.07 1.93
fh(GHz) 4.33 5.54 5.41 5.28
S11(dB) -15.80 -11.40 -15.80 -16.1
Gain (dBi) 2.45 2.21 2.32 2.45
Parameter Flat Crumpled
fl(GHz) 2.43 2.41
fh(GHz) 2.48 2.42fr(GHz) 2.46 2.42
Gain atfr(dBi) 8.55 6.98
Gain at 2.45 GHz (dBi) 8.41 6.80
S11at fr (dB) -23.50 -21.80
S11at 2.45 GHz (dB) -12.00 -7.00
