This article has been accepted for publication in a future issue of this journal, but has not been

fully edited. Content may change prior to final publication. Citation information: DOI 10.1109/TAP.2018.2811844, IEEE
Transactions on Antennas and Propagation
H. Li et al.: Design of Compact Single-layer Textile MIMO antenna for Wearable Applications

Design of Compact Single-layer Textile MIMO antenna for Wearable

Applications

H. Li, Member IEEE, S. Sun, B. Wang and F. Wu


isolate the antenna from the human tissue. However, they are
Abstract—A compact single-layer textile MIMO antenna is designed normally multi-layer structures, and sensitive to bending and
for wearable applications. The theory of characteristic mode is used to crumpling. To design simple antennas against crumpling, dual-layer
guide the antenna design and analyze its performance. The MIMO antennas, including E-shaped PIFA [6] and dual-band slot [7] were
antenna utilizes a small ground plane as the main radiator, capacitively proposed. A dual-layer circular quarter-mode textile antenna was
loaded by two strips along two orthogonal edges. The whole system also introduced, where the shorting posts along the periphery were
occupies a volume of 38.1 mm × 38.1 mm × 2 mm, with each antenna
used to form magnetic walls for size reduction [8]. Regarding
having a dipole-like radiation pattern of linear polarization. Good
isolation of above 12 dB is achieved due to the quasi-orthogonal radiations
single-layer wearable antennas, a CPW fed integrated IFA with a
generated by the two antennas, providing pattern and polarization wide bandwidth of 25% has been investigated in [9], but its on-body
diversities. The envelope correlation coefficient (ECC) between the performance was not presented. So far, most of the proposed
antennas is below 0.01. The proposed antenna, fabricated on a flexible felt wearable antennas are linearly polarized, which may lead to
with a permittivity of 1.2, has a wide bandwidth of 20%. Due to its unreliable wireless links due to the environment changing. In [10], a
broadband behavior, the antennas remain well matched at the target circularly polarized wearable antenna was studied to combat with
band when worn on the body and bended. The loss of the human tissue polarization mismatch. But its configuration was complicated with
results in the drop of the antenna gains to 1.6 dBi and 1.2 dBi, respectively, four layers and several shorting vias, occupying a large footprint.
for the two antennas. The proposed antenna is competitive for wearable Multi-antenna system with polarization and pattern diversities is
applications, due to its compact size, single layer structure, easy
a good option to overcome polarization mismatch and establish
integration, robustness, and reasonable on-body antenna gain.
robust channels. This paper presents a dipole-based single-layer
Index Terms—Antenna array, body area network (BAN), MIMO antenna system with large bandwidth for wearable
compact antenna, MIMO system, theory of characteristic mode, applications. The two dipoles are constructed by loading the ground
wearable antenna. plane with two strips on the orthogonal edges, providing
polarization and pattern diversities. The dipole antennas take
advantage of the ground plane to radiate so that the currents are
more uniformly distributed, leading to low SAR values. Section II
I. INTRODUCTION
utilizes the theory of characteristic mode to analyze the feeding
In recent years, wearable devices have received significant arrangement of the antenna, in order to achieve good orthogonality
attention due to its widespread applications, such as sports between two linearly polarized elements. The antenna is designed
monitoring, health care, navigation and so on [1]-[3]. Antenna is a and simulated in section III, both in free space and in wearable
critical part for the performance of the wearable links. The design of scenarios. The prototype is then fabricated, with the measurement
wearable antennas is challenging. Firstly, the wearable antennas are results given in section IV. Section V concludes the performance of
required to radiate efficiently and effectively in various the proposed antenna.
environments, such as bending and body movement. To provide
better user experience, the antennas need to be compact, low profile II. MODE ANALYSIS OF ANTENNA
and light weight so that they are easy to be integrated in the clothes
Characteristic mode analysis is an efficient method to gain
and other devices. Moreover, considering that the antenna is very
physical insights into potential resonant and radiation characteristics
close to the human body, good on-body performance is in demand,
of a structure by finding and examining its inherent modes [14], [15].
and specific absorption rate (SAR) limitations should be fulfilled
We begin with analyzing the CMs of a square plate (Fig. 1(a)) and
from health perspective.
the same plate capacitively loaded with a strip (Fig. 1(b)). The size
It has been reported that the antenna performance degrades
of the square plate is 32 mm × 32 mm. The strip is connected with
dramatically when in close proximity to the human body due to two
the plate using a shorting line with a length of 3 mm. The
reasons. On one hand, the antenna is detuned due to the loading of
eigenvalue curves of the two structures corresponding to the first
the human tissue with high permittivity and high loss, especially for
three modes are presented in Fig. 1(c).
narrow band antennas. On the other hand, power is absorbed by the
For the square plate, the first and the second modes, which
human tissue so that the radiation efficiency of the antenna drops. A
resonate at around 5.2 GHz, overlap with each other as the lengths of
number of literatures have investigated suitable wearable antennas
the plate are the same along x and y axis. They represent the x- and y-
[4]-[13]. To overcome the performance deterioration of the antenna
orientated dipole modes, respectively. For the one-strip loaded plate,
near the human body, high impedance surface (HIS) [4] and
the resonant frequency of the x-orientated dipole mode moves down
electromagnetic bandgap (EBG) structures [5] were utilized to
to 2.4 GHz since the strip increases its electrical length and provides
capacitive loading. On the other hand, the y-orientated dipole mode
Manuscript received July 24th, 2017. This work was supported partly by:
(1) National natural science foundation of China (no. 61601079); (2)
keeps almost unchanged. In order to investigate how the radiations
Provincial natural science foundation of Liaoning (No. 20170540169). of the CMs are changed by the loaded strip, we obtain the
H. Li and F. Wu are with the Affiliated Zhongshan Hospital of Dalian characteristic far fields of each mode for the single plate and the
University, Dalian, 116001, China; H. Li is also with School of Information strip-loaded plate at the resonant frequencies. Envelope correlation
and Communication Engineering, Dalian University of Technology, Dalian, coefficient (ECC) is then calculated between the modes of different
116024, China. E-mail: hui.li@dlut.edu.cn. structures, using the full spherical characteristic patterns with both
S. Sun and B. Wang are with School of Information and Communication phase and polarization information [16]. The results are shown in
Engineering, Dalian University of Technology, Dalian, 116024, China. Table I. It is observed that the modes labeled with the same number

0018-926X (c) 2018 IEEE. Personal use is permitted, but republication/redistribution requires IEEE permission. See http://www.ieee.org/publications_standards/publications/rights/index.html for more information.
This article has been accepted for publication in a future issue of this journal, but has not been fully edited. Content may change prior to final publication. Citation information: DOI 10.1109/TAP.2018.2811844, IEEE
Transactions on Antennas and Propagation
H. Li et al.: Design of Compact Single-layer Textile MIMO antenna for Wearable Applications

are highly correlated, indicating that the radiation characteristics of

the modes are not changed, though the resonant frequencies of mode
2 are different.

(c)
Fig. 2. (a) The configuration of two-strip loaded plate, position 1 (P1); (b)
The configuration of two-strip loaded plate, position 2 (P2); (c) Eigenvalues
of the two-strip loaded plates.
(c)
Fig. 1. (a) The configuration of the square plate with the size of 32 mm ×32
mm; (b) The configuration of the square plate loaded with one strip; (c)
Eigenvalues of the plates.
TABLE I
ENVELOPE CORRELATION COEFFICIENT BETWEEN MODES OF DIFFERENT
STRUCTURES
Single plate Mode 1 Mode 2
ECC
1 2

One-strip 1 0.95 0.0076 (a) (b)

loading 2 0.0093 0.98

Fig. 3. Characteristic far fields of the two-strip loaded plates: (a) mode 1; (b)
Two-strip 1 0.56 0.27
mode 2.
loading, P1 2 0.32 0.68
ECCs between the characteristic patterns of the two-strip loaded
Two-strip 1 0.58 0.39 plate and the single plate in Fig. 1(a) can be found in Table I. It is
loading, P2 2 0.38 0.54 seen that each inherent mode of the two-strip loaded plate is a
combination of the two modes of the square plate, as expected from
Since the dipole mode is of linear polarization, in order to the characteristic patterns of the two-strip loaded plate in Fig. 3.
establish robust channels, we build a second antenna with When the shorting strips are replaced by the feedings, the excited
orthogonal polarization by loading another strip in the y direction. radiations are no longer purely along the diagonal direction. The
Two loading methods with different shorting strip locations (P1, P2) excited dipole-like radiations are noted by the arrows in Fig. 2(a)
are investigated, as depicted in Fig. 2(a) and (b). We focus on the and (b), respectively. Comparing the two structures, it is seen that
characteristics of the first two modes, and present their eigenvalues the two excited radiations are more orthogonal for P2 than for P1,
in Fig. 2(c). For both structures, there are two modes resonating though the feedings of the two strips are closer to each other in P2.
between 2 GHz and 2.5 GHz, with similar eigenvalue behaviors Thus, P2 is preferred considering the mutual coupling between the
within the frequency band. antennas. This will be further verified by the isolation between the
The characteristic far fields of the first two modes are investigated antenna elements in the full wave simulations.
and presented in Fig. 3. Different from the x- and y-oriented dipole
modes of the plate, the inherent modes of the two-strip loaded III. ANTENNA DESIGN
antennas are along the diagonals of the structure. Though the strips
A. Antenna Setup
in the y direction are shorted at different positions for the two
structures, the radiation characteristics of the first two inherent A MIMO antenna system is designed according to the
modes are very similar. This was concluded from the high ECC of configuration in Fig. 2(b), with the final detailed geometries shown
above 0.9 between the characteristic fields of the modes labeled in Fig. 4. The antenna occupies an area of 38.1 mm ×38.1 mm, with
with the same number for the two structures. a thickness of 2 mm. It is implemented on a substrate with the
permittivity of 1.2. The tails of the strips are curved in order to
achieve good impedance matching over a wider band [17]. The
shorting strips in the CM analysis are simply replaced by the lumped
ports in the simulation, and a shunt inductance of 2 nH is

0018-926X (c) 2018 IEEE. Personal use is permitted, but republication/redistribution requires IEEE permission. See http://www.ieee.org/publications_standards/publications/rights/index.html for more information.
This article has been accepted for publication in a future issue of this journal, but has not been fully edited. Content may change prior to final publication. Citation information: DOI 10.1109/TAP.2018.2811844, IEEE
Transactions on Antennas and Propagation
H. Li et al.: Design of Compact Single-layer Textile MIMO antenna for Wearable Applications

implemented next to each port. The longer and shorter strips on frequencies. It is observed that smaller radius does not mean greater
different sides of the feedings correspond to the low and high frequency shift. The antenna is even slightly less detuned for Rx = 20
resonant frequency bands, respectively. In this work, we mainly mm than for Rx = 40 mm. Even though the center frequency is
focus on the low band of ISM (2.4 GHz-2.485 GHz) for wearable shifted, the input impedance is still well matched in the ISM band
applications. The operating frequency of the high band can be tuned for both bending scenarios. For the concise of the paper, we did not
by changing the length of the shorter part of the strip (L2). show the performance of the antennas when bended along y-axis, as
similar effects, which take place on antenna 1, are observed.
L
Port 2

W3
W4

L2

Port 1

W1
(a) (b)

y
W2

L3 z x
L1

Fig. 4. The geometries of the proposed wearable MIMO antenna. The

dimensions are: L= 38.1 mm, L1=32.5 mm, L2=7.6 mm, L3=3.5 mm, W1=28.8
mm, W2=11 mm, W3=6.6 mm, W4=2.5mm, d=1 mm.

(c)
Fig. 6. (a) Antenna deformation: Rx= 40 mm; (b) Antenna deformation: Rx=
20 mm; (c) S-parameters for different bending radii.

In order to investigate the influence of the human body, the

antenna is placed on the human arm, which is simulated as a
four-layer cylinder, including skin, fat, muscle, and bone, as shown
in the inset of Fig. 7. The thicknesses of the four layers are 2, 5, 20,
and 13 mm, respectively, with their material properties at 2.45 GHz
Fig. 5. S-parameters of the MIMO antennas for different feeding locations. shown in Table II [6]. Fig. 7 shows the S-parameters of the antennas
when fully attached on the arm. Compared with the S-parameters in
The simulated S-parameters of the proposed antenna in free Fig. 5, the center frequency is detuned to the lower band by 250
space are shown in Fig. 5. To validate the significance of the feeding MHz due to high permittivity loading, and the isolation is enhanced
position, the S-parameters of the configuration in P1 are also by 5 dB attributed to body loss. As the bandwidths of the antennas
compared in the figure. It is observed that the antennas in both are large in free space, the antennas are still well matched from 2.4
MIMO systems are well matched at the ISM band. Regarding the to 2.5 GHz after frequency shift.
mutual coupling, the worst isolation between the antenna elements However, due to the high loss of the body tissue, the radiation
in setup P1 is 6.5 dB, whereas it is 12 dB in setup P2. As efficiencies of the antennas are dropped to 19% when stuck to the
demonstrated in the CM analysis, the hybrid modes excited by the arm. In practice, it is quite common to integrate the antenna on the
feedings in P2 are more orthogonal than those in P1, leading to the clothes, so that the antenna is in proximity, rather than stuck, to the
isolation enhancement. The proposed MIMO antennas cover a wide human arm. In this case, we separate the antenna from the arm by h
bandwidth of 450 MHz and 500 MHz, respectively, for port 1 and = 3 mm. As expected, the resonant frequencies of the antennas are
port 2 with |S11| < -10 dB. The ECCs calculated from the far field less shifted compared to the case with h = 0 mm, and the impedance
patterns are below 0.01 over the operating band. matching remains good. The S-parameters are not shown here for
B. Analysis for Wearable Applications the concise of the paper. The total efficiencies and gains of the
antennas are illustrated in Fig. 8. As can be seen, the efficiencies of
For wearable applications, the antennas are required to be
the antennas are above 27% at the ISM band. Though the
conformal with the human body and the clothes, and they might also
efficiencies are not high, the gains are still above 1.6 dBi and 1.2 dBi
suffer from deformation due to body movement. We first examine
for antenna 1 and antenna 2, respectively, only slightly smaller than
how the antenna performance is influenced by the deformation in
those in free space (around 1.95 dBi for both antennas). This is
free space. For this study, the antenna is bended along x-axis.
because the power loss happens mainly on the side of the body tissue,
Different bending radii of 40 mm and 20 mm are chosen to represent
and the directivities of the antennas are increased to 6.57 dBi and 5.9
human arms of different sizes (see Fig. 6(a) and (b)). Fig. 6(c) shows
dBi, respectively, for the two antennas, which are higher than those
the S-parameters for different bending radii. In both cases, antenna 1
in free space (around 2.5 dBi for both antennas). Thus, the forward
along y-axis does not suffer from much deformation so that its
communication between the wearable antenna and other devices
reflection coefficients keep almost unchanged. On the other hand,
(such as mobile phone) is not greatly deteriorated. The ECCs
the bending of antenna 2 leads to frequency shifts towards lower
between the antennas in proximity to the arm are still below 0.01.

0018-926X (c) 2018 IEEE. Personal use is permitted, but republication/redistribution requires IEEE permission. See http://www.ieee.org/publications_standards/publications/rights/index.html for more information.
This article has been accepted for publication in a future issue of this journal, but has not been fully edited. Content may change prior to final publication. Citation information: DOI 10.1109/TAP.2018.2811844, IEEE
Transactions on Antennas and Propagation
H. Li et al.: Design of Compact Single-layer Textile MIMO antenna for Wearable Applications

Simulations are also carried out with both the arm and the human simulations due to the handmade process.
body presented, where flat phantom is used to simplify the model of
the human body. Similar S-parameter results as in Fig. 7 were
obtained, and the gains are around 1 dB higher than the case with
only the arm presented due to the more directive pattern as a result
of the reflection of the human body.

Fig. 9. The fabricated prototype of the proposed MIMO antenna system for
wearable applications.

Fig. 7. S-parameters for arm-loaded MIMO antenna.

TABLE II
MATERIAL PROPERTIES OF HUMAN ARM MODEL
skin fat muscle bone
r 37.95 5.27 52.67 18.49
Conductivity (S/m) 1.49 0.11 1.77 0.82
Density (kg/m3) 1001 900 1006 1008

Fig. 10. The measured S-parameters of the proposed MIMO antenna in free
space and on the arm.

The S-parameters of the MIMO antennas in free space and on the

arm were measured with a vector network analyzer and shown in
Fig. 10. For the on-arm measurement, the antennas were placed
directly on the arm and conformal with the arm, as shown in the
inset of Fig. 10. To keep the measurement results relatively stable,
the arm stays on the table. Though the whole body was present
during the measurement, its effect on the measurement results is
limited. The measured results show that both antennas cover the
ISM band with an isolation of above 10 dB. The arm-worn scenario
brings down the resonant frequency by around 200 MHz, and
enhances the isolation by 3.5 dB, which agree reasonably well with
the simulation results. The discrepancy could be due to the
fabrication tolerance, the prototype not being tightly attached to the
Fig. 8. The total efficiencies and gains of the antennas when the antenna arm and the parameters of the real arm being different from those of
system is placed 3 mm above the arm. the cylindrical phantom in the simulation.
The far-field patterns of the proposed MIMO antenna in free
Since the antennas have non-negligible backward radiation, SAR space were measured in an anechoic chamber, and normalized to
needs to be considered. Flat phantom (i.e., body-worn scenario) is their maximum values. The smoothed measured patterns on the
chosen in this study as in most of the SAR investigations. The three main planes are compared with the simulation results in Fig.
antennas are placed 3 mm above the phantom. An accepted power of 11. In general, the measured patterns agree well with the simulated
24 dBm (0.25 W), which excludes the mismatch factor, is used in
ones. Slight differences occur at the theta = 90 plane, at around phi
the simulation. At 2.45 GHz, the maximum stand-alone SAR values
of 0.203 W/kg and 0.22 W/kg averaged over 1 g tissue are observed = 330 and phi= 60 , which correspond to the locations of the
for antenna 1 and 2, respectively, which fall well within the FCC SMA connectors and the feed cables. It can be observed from the
specifications of 1.6 W/kg. patterns that both pattern and polarization diversities are achieved in
the proposed antennas. Since the final radiations are not purely
IV. EXPERIMENTS AND DISCUSSIONS theta- or phi- polarized, the polarizations of the two antennas are
actually more orthogonal than those read from the figure.
The proposed MIMO antenna system was fabricated on a felt
substrate with the thickness of 2 mm and relative permittivity of 1.2,
as shown in Fig. 9. As in the simulation, one inductor of 2 nH was
soldered next to each feed in the prototype. The SMA cables were
soldered near the edges of the ground plane. The shape and the
length of the antennas might be slightly different from those in the

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This article has been accepted for publication in a future issue of this journal, but has not been fully edited. Content may change prior to final publication. Citation information: DOI 10.1109/TAP.2018.2811844, IEEE
Transactions on Antennas and Propagation
H. Li et al.: Design of Compact Single-layer Textile MIMO antenna for Wearable Applications

communication range. As the non-invasive and low cost substrate is

used in the proposed antenna, it is suitable for medical applications,
such as health monitoring.
As for the actual integration of the proposed antenna, it could be
placed inside the nylon strap worn around the wrist or arm. Or we
can use non-woven conductive fabrics (NWCF) as conductive part
of the antenna system, and integrate it with clothing (such as jeans)
directly, as in [18]. Other fabrication techniques, such as embroidery
of the conducting threads and 3D printing, also provide possible
integration with clothing.

V. CONCLUSIONS
In this paper, a flexible MIMO antenna system with polarization
and pattern diversities has been proposed for wearable applications.
The antenna has only one conducting layer and is easy to integrate in
the clothing. CM was utilized to design and analyze the performance
Fig. 11. The normalized simulated and measured radiation patterns of the of the antennas before full wave simulations. The compact MIMO
proposed MIMO antennas at 2.45 GHz: (–.) E-theta, simulated; (––) E-phi, antenna with the size of 38.1 mm ×38.1 mm was fabricated on the
simulated; (···) antenna 2, measured, (– –) E-phi, measured. felt with the thickness of 2 mm. The antenna system operates over a
wide band with a fractional bandwidth of 20%, and has been verified
TABLE III
COMPARISON WITH THE STATE-OF-THE-ART ANTENNAS to be robust to the bending and body movement. Antenna gains of
above 1.6 dBi and 1.2 dBi are obtained, respectively, for the two
Gain
antennas in the body-worn and bending scenario, ensuring reliable
Size
Layers Bandwidth (free
Gain
Polarization
wearable communication links between the proposed antenna
(mm×mm×mm)
space)
(on body) system and other devices.

[4] 38*38*3 3 6.2% 2.92 2.1 linear REFERENCES

[5] 63*38*6.57 3 4.88% 7 6.88 linear
[6] 46*25*2 2 3.27% 0.64 - linear [1] P. S. Hall and Y. Hao, Antenna and Propagation for Body-Centric
Wireless Communications. Norwood, MA, USA: Artech House, 2012.
[9] 76*30*1.58 1 25% 2.3 - linear
[2] C. Roblin et al., “Antenna design and channel modeling in the BAN
[10] 66.3*66.3*8.75 4 12.2% 5.2 4.7 circular context—Part I: Antennas,” Ann. Telecommun., vol. 66, no. 3, pp.
3.5 139–155, Jan. 2011.
[11] 100*100*6 3 20% 4.7 (Bending linear [3] S. Hong, S Kang, Y. Kim and C. Jung, “Transparent and flexible
only) antenna for wearable glasses applications,” IEEE Trans. Antennas
Propag., vol. 64, no. 7, pp. 2797-2804, Jul. 2016.
Prop. 38.1*38.1*2 1 20% 2.79 1.67 dual [4] Y. Chen and T. Ku, “A low-profile wearable antenna using a miniature
high impedance surface for smartwatch applications” IEEE Wireless
The proposed single-layer textile MIMO antennas are compared Antenna Propag. Lett., vol. 15, pp. 1144-1147, 2016.
with other state-of-the-art wearable antennas in Table III, in [5] M. Abbasi, S. Nikolaou, M. Antoniades, M. Stevanovic and P.
perspective of size, number of layers, bandwidth, polarization, and Vryonides, “Compact EBG-backed planar monopole for BAN
gain on and off the body. Most of the antennas work at the ISM band wearable applications,” IEEE Trans. Antennas Propag., vol. 65, no. 2,
for fair comparison. For the antennas working at other frequencies, pp. 453-463, Feb. 2017.
[6] B. Hu, G. Gao, L. He, X. Cong and J. Zhao, “Bending and on-arm
e.g., in [10], their dimensions are transformed to the equivalent size effects on a wearable antenna for 2.45 GHz body area network,” IEEE
at 2.45 GHz according the electrical length. Firstly, most of the Wireless Antenna Propag. Lett., vol. 15, pp. 378-381, 2016.
existing antennas are linearly polarized, with only the antenna [7] E. Sundarsingh, S. Velan, M. Kanagasabai, A. Sarma, C. Raviteja and
proposed in [10] being circularly polarized. However, the antenna in M. Alsath, “Polygon-shaped slotted dual-band antenna for wearable
[10] has four layers with complex structures, which is not easy for applications,” IEEE Wireless Antenna Propag. Lett., vol. 13, pp.
611-614, 2014.
fabrication and integration in clothing. The proposed antenna [8] S. Agneessens, S. Lemer, T. Vervust and H. Rogier, “Wearable, small,
system, on the other hand, utilizes dual linear polarized antennas to and robust: the circular quarter-mode textile antenna,” IEEE Wireless
enhance the channel stability. Secondly, similar as the antennas in Antenna Propag. Lett., vol. 14, pp. 1482-1485, 2015.
[10], in order to isolate the antenna from the body, most of the [9] W. Hajj, C. Person and J. Wiart, “A novel investigation of a broadband
wearable antennas are thicker and have more than 2 layers, causing integrated inverted-F antenna design: application for wearable
antenna,” IEEE Trans. Antennas Propag., vol. 62, no. 7, pp. 3843-3846,
the same problem of difficult integration. The antenna proposed in Jul. 2014.
[6] has only two layers and small footprint, but it has a smaller [10] Z. Jiang and D. Werner, “A compact, wideband circularly polarized
bandwidth and a lower gain even in free space. In [9], a single layer co-designed filtering antenna and its application for wearable devices
antenna was proposed for wearable applications. But the on-body with low SAR,” IEEE Trans. Antennas Propag., vol. 63, no. 9, pp.
performance of the antenna was not well analyzed in the paper. 3808-3818, Sep. 2015.
[11] S. Agneessens and H. Rogier, “Compact half diamond dual-band
Moreover, it has a larger lateral size than the proposed antenna and textile HMSIW on-body antenna,” IEEE Trans. Antennas Propag., vol.
is of single polarization. Regarding the on-body gain, the proposed 62, no. 5, pp. 2374-2381, May. 2014.
antenna is relatively small compared with the antennas with more [12] S. Yan, P. Soh, and G. A. E. Vandenbosch, “Wearable dual-band
than 2 layers, and is similar or even higher than the antennas with magneto-electric dipole antenna for WBAN/WLAN applications,”
one or two layers, as can be observed and estimated from the table. IEEE Trans. Antennas Propag., vol. 63, no. 9, pp. 4165-4169, Sep.
2015.
In summary, the proposed antenna is competitive in perspective of [13] X. Hu, Y. Sen and V. Guy, “Wearable button antenna for dual-band
its small size, easy fabrication and integration, dual-polarization, WLAN applications with combined on and off-body radiation
robustness against the human tissue and movement, and fairly good patterns,” IEEE Trans. Antennas Propag., vol. 65, no. 3, pp. 1384-1387,
antenna gains on the human body. Those properties provide Mar. 2017.
comfortable wearing experience and enables a longer

0018-926X (c) 2018 IEEE. Personal use is permitted, but republication/redistribution requires IEEE permission. See http://www.ieee.org/publications_standards/publications/rights/index.html for more information.
This article has been accepted for publication in a future issue of this journal, but has not been fully edited. Content may change prior to final publication. Citation information: DOI 10.1109/TAP.2018.2811844, IEEE
Transactions on Antennas and Propagation
H. Li et al.: Design of Compact Single-layer Textile MIMO antenna for Wearable Applications

[14] H. Li, Y. Tan, B. K. Lau, Z. Ying, and S. He, “Characteristic mode

based tradeoff analysis of antenna-chassis interactions for multiple
antenna terminals,” IEEE Trans. Antennas Propag., vol. 60, pp.
490-502, Feb. 2012.
[15] H. Li, Z. Miers, B. K. Lau, “Design of orthogonal MIMO handset
antennas based on characteristic mode manipulation at frequency
bands below 1 GHz,” IEEE Trans. Antennas Propag., vol. 62, no. 5, pp.
2756-2766, May 2014.
[16] R. Clarke, “A statistical theory of mobile radio reception,” Bell System
Technical Journal, no. 2, pp. 957-1000, 1968.
[17] Z. Miers, H. Li, B. K. Lau, “Design of bandwidth enhanced and
multiband MIMO antennas using characteristic modes,” IEEE
Antennas Wireless Propag. Lett., vol. 12, pp. 1696-1699, 2013.
[18] L. Corchia, E. De. Benedetto, G. Monti, A. Cataldo and L. Tarricone,
“Wearable Antennas for Applications in Remote Assistance to Elderly
People,”in IEEE International Workshop on Measurement and
Networking(M&N), Naples, Italy, 2017, pp. 1-6.

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