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Design of a compact superstrate-loaded slotted implantable antennafor ISM band applications
GURPRINCE SINGH* and JASWINDER KAUR
Department of Electronics and Communication Engineering, Thapar Institute of Engineering and Technology,
Patiala, Punjab, India
e-mail: [email protected]
MS received 14 January 2021; revised 17 April 2021; accepted 18 July 2021
Abstract. In this paper, the design of a simple rectangular slotted inset-cut fed implantable antenna is pro-
posed. By using slotting technique in patch as well as ground plane, the size of the proposed antenna is reduced
significantly to 10.2 9 8.61 9 1.92 mm3 with very small patch size of 6.2 9 4.5 mm2 suitable for
implantable biotelemetry application around 2.45 GHz Industrial, Scientific and Medical (ISM) band. An
appreciable fractional bandwidth of 13.7% with a good return loss of - 20.02 dB has been achieved. In-vitro
analysis of the antenna prototype is carried out by inserting the prototype into skin mimicking liquid.
Keywords. Biotelemetry application; implantable antenna; in-vitro; ISM band; slotted; superstrate-loaded.
1. Introduction
Biotelemetry means transferring biological signals from
human or animal body and remotely detecting them wired
or wirelessly. This is used widely in transferring medical
parameters from a patient to external receiving or moni-
toring devices. For biotelemetry, two types of devices are
used: on-body and body-implantable devices. Many people
are dependent on implantable devices like blood glucose
monitor [1], cochlear implant [2], retinal implant [3],
Functional Electrical Stimulators (FES) [4] and pacemakers
[5], etc.
Generally, two main frequency bands are used for
making these wireless transmission devices which contain
antennas working at ISM [2.4–2.48 GHz] band and Medi-
cal Implant Communications Service (MICS)
[402–405 MHz] band [6–10]. In our proposed work, we are
designing an implantable antenna keeping in mind the
following challenges such as miniaturization, biocompati-
bility and Specific Absorption Rate (SAR) limitation. As
the antenna needs to be inserted inside skin therefore, it has
to be as small as possible. For making a compact size
antenna, many techniques are used such as Planar Inverted-
F Antenna (PIFA) [11], shorting pin [12, 13], patch stack-
ing [14, 15], meandered [6, 16], spiral [17–20] shaped
designs and use of high dielectric materials [21–23]. Next
challenge faced is that the antenna has to be biocompatible
to the human body. As the antenna is inserted permanently
inside body therefore it must not react with the nearby
tissues causing serious problems to the human body. The
reason of antenna reacting with nearby tissues is the
metallic layer (patch and ground layer are made of copper)
on it, and the human tissues are conductive in nature cre-
ating short circuits [6]. For avoiding this problem, the
antenna is either made or covered using a high dielectric
material called superstrate which does not react with body
tissues thus making the antenna biocompatible. Some
common superstrate materials are Rogers RT/duroid 3010
(er = 10.2, tand = 0.0022), Rogers RT/duroid 3210 (er =10.2, tand = 0.003), Rogers RT/duroid 6010 (er = 10.2,
tand = 0.0035) and Alumina (er = 9.4, tand = 0.006), etc.
Superstrate and substrate layer of antenna can be made
from the same material [7, 9]. Another challenge in making
an implantable antenna is maximum allowable limit of
SAR which ensures patient’s safety. According to IEEE
C95. 1-1999 standard the limit of maximum allowable
input power given to antenna to protect human body should
be kept lower than 1.6 W/kg for any 1-g averaged tissue of
cubic shape [SAR1g,max B 1.6 W/kg] and according to
IEEE C95. 1-2005 for any 10-g averaged tissue of cubic
shape it should be kept lower than 2 W/kg [SAR10g,max-
B 2 W/kg] [6, 24–28]. The antenna is simulated using a
three-dimensional simulation software CST MWS before
fabrication so that the approximate results can be calcu-
lated. For simulation, the antenna is inserted inside single
layer or multi-layered [three-layer or five-layer] model
using layers of skin, fat, muscle and bone. For testing
purposes the antenna can be tested using in-vitro, ex vivo or
in-vivo technique whichever possible. If testing of antenna
is done inside the whole animal then it is termed as in-vivo.
If testing is done by taking a tissue sample of an animal
then it is called as ex-vivo testing. Whereas if the testing of*For correspondence
Sådhanå (2021) 46:164 � Indian Academy of Sciences
https://doi.org/10.1007/s12046-021-01691-4Sadhana(0123456789().,-volV)FT3](0123456789().,-volV)
antenna is done in body phantom that is made by preparing
homogenous [single layer tissue] or inhomogeneous [multi-
layer tissue] solutions of skin, muscle, bone, fat or their
combinations, then this type of testing is known as in-vitro
testing. In-vitro testing of implantable antennas made for
human body have to go through many tests before inserting
inside the body because insertion of any foreign element in
body can cause serious problems. Therefore, before
inserting anything inside the body, some scientific testing
must be done even after software simulations. The body
phantoms are made by the mixture of water, sugar, salt and
oil, etc. for obtaining the required electrical permittivity
and conductivity which matches the properties of human
body tissues. These solutions are made in cylindrical,
rectangular or square boxes depending upon the type of
implantable area.
Figure 1. Geometrical representation of the proposed antenna. (a) Radiating patch. (b) Ground plane. (c) Fabricated antenna without
superstrate layer. (d) Fabricated antenna with superstrate layer.
Table 1. Geometrical parameters of the proposed antenna in mm
Parameter Value Coordinates
Ls 8.61 (- 4.25,5.1) (4.36,5.1)
Ws 10.2 (- 4.25,- 5.1) (- 4.25,5.1)
PL 4.5 (- 2.25,3.1) (2.25,3.1)
Pw 6.2 (- 2.25,- 3.1) (- 2.25,3.1)
P1 2 (- 1,0) (1,0)
P2 3 (- 1.5,- 3.1) (1.5,- 3.1)
P3 4.86 (1.5,- 0.33) (4.36,- 0.33)
Lg 8.61 (- 4.25,5.1) (4.36,5.1)
Wg 10.2 (- 4.25,- 5.1) (- 4.25,5.1)
r1 1.5 (0,0) (0,1.5)
g2 7.7 (2.25,- 3.1) (2.25,4.6)
g3 4.1 (- 2.25,- 4.1) (- 2.25,0)
Lg1 2.25 (0,- 3.1) (2.25,- 3.1)
Lg2 2.25 (- 2.25,- 4.1) (0,- 4.1)
164 Page 2 of 10 Sådhanå (2021) 46:164
(Case 1) (Case 2)
(Case 3) (Case 4)
(a)
(b) (c) (d)
2.0 2.2 2.4 2.6 2.8 3.0-35
-30
-25
-20
-15
-10
-5
0
S 11 (
dB)
Frequency (GHz)
Case 1 Case 2 Case 3 Case 4
2.0 2.2 2.4 2.6 2.8 3.0
-40
-35
-30
-25
-20
-15
-10
-5
0
Ret
urn
loss
(dB)
Frequency (GHz)
r1=0.5 r1=1 r1=1.5 r1=2 r1=2.5 r1=3
2.0 2.2 2.4 2.6 2.8 3.0
-35
-30
-25
-20
-15
-10
-5
0
S 11(
dB)
Frequency (GHz)
g2=7.2 g2=7.45 g2=7.7 g2=7.95 g2=8.2
Figure 2. Evolution of the proposed antenna inside skin layer. (a) Evolution of the ground plane of proposed antenna. (b) Comparison
of return loss for three different configurations of ground plane. (c) Comparison of return loss of proposed antenna with different r1.
(d) Comparison of return loss of proposed antenna with different g2.
Sådhanå (2021) 46:164 Page 3 of 10 164
In this paper, a miniaturized implantable patch antenna is
proposed for medical applications like Intracranical Pres-
sure (ICP) monitoring when inserted inside scalp on the top
of brain [7]. Slotting technique is used in the radiating patch
and ground plane for reducing the size of antenna as well as
increasing the bandwidth. The overall size of the proposed
antenna is 10.2 9 8.61 9 1.92 mm3 which is considerably
small. At the same time, the size of patch is reduced to
6.2 9 4.5 mm2 which is among the smallest patch sizes
developed in the present literature. A high dielectric bio-
compatible material Rogers RT/duroid 3010 is used in
making and encasing the proposed antenna. With this small
size and covering the antenna with biocompatible layers on
both sides make the antenna novel as well as best contender
to be used in implantable devices. In-vitro testing is done
for this fabricated antenna using a single layer skin mim-
icking liquid. The proposed antenna works at ISM band and
produces appreciable results in terms of bandwidth, SAR,
volume factor and peak gain. The detailed antenna structure
with simulated and measured results are discussed in the
succeeding sections.
2. Antenna design
A high dielectric material Rogers 3010 (2r = 10.2 and
tand = 0.0022) is used both as a substrate as well as
superstrate for making the antenna compatible to human
body tissues having thickness 0.64 mm each thus making
an overall thickness of antenna as 1.92 mm. figure 1 shows
the geometrical representation of proposed antenna with
dimensions 10.2 9 8.61 mm2 having a small patch size of
6.2 9 4.5 mm2.
Figure 1a shows the radiating patch layer of antenna
having a circular slot at the centre of radius 1 mm and a
semi-circular slot at the bottom of the patch of radius
1.5 mm. An inset feed line of length 2.86 mm and width
0.66 mm is used for feeding the antenna. The advantage of
using an inset feed line over other feeding methods is that it
is simple to model as well as can easily be fabricated. It
also helps to achieve good impedance matching. Two
vertical rectangular slots are introduced in the ground plane
below the patch in which first one is of dimensions
4.1 9 2.25 mm2 and another one is of dimensions
7.7 9 2.25 mm2. Moreover, a circular slot of radius
1.5 mm is introduced at the centre of ground plane which
makes the overall defect to resemble as if it is a quadrant
shaped slot, reason behind is that it merges with the two
rectangular slots shown in figure 1b. The proposed antenna
with and without superstrate is shown in figure 1c and
figure 1d respectively. The detailed parameters of patch and
ground plane are listed in table 1.
2.1 Evolution of the ground plane of proposedantenna
Figure 2a shows evolution of the proposed antenna with
respect to ground. Slotting technique is applied in the
ground plane to obtain the desired result at ISM band of the
proposed antenna. The ground plane basically consists of
two rectangular slots having dimensions 7.7 9 2.25 mm2
and 6.4 9 2.25 mm2 with one circular slot of radius
1.5 mm which has been just introduced below the centre of
radiating patch. The resonant behaviour of these three slots
in the ground plane analysed in terms of return loss is
depicted in figure 2b as four cases: Case 1, Case 2, Case 3
and Case 4 and the results obtained are illustrated in
Table 2. In Case 1, antenna’s ground plane is shown before
applying any slotting technique. From figure 2b it is clear
that without slotting, the antenna does not resonate. In Case
2, the bigger rectangular slot is constructed for which the
resonant frequency obtained is 2.63 GHz covering a
bandwidth of 2.44–2.87 GHz with a return loss of
- 30.79 dB. As can be seen from the bandwidth spectrum
achieved, the desired ISM band (2.4–2.48 GHz) is not fully
covered. Therefore, this configuration of ground plane is
not good enough to satisfy our application. In Case 3, the
smaller rectangular slot is added to the ground plane in
Table 2. Performance characteristics of the ground plane of
antenna for three different cases.
S11 in
dB
Bandwidth
in GHz
Resonant
frequency (GHz)
Case 1 – – –
Case 2 - 30.79 2.44–2.87 2.63
Case 3 - 16.30 2.28–2.57 2.42
Case 4 - 20.02 2.31–2.65 2.475
Table 3. Performance characteristics of the proposed antenna
with different r1.
r1
(mm)
S11 in
dB
Bandwidth
(GHz)
Resonant frequency
(GHz)
0.5 - 16.66 2.28–2.59 2.43
1 - 17.67 2.3–2.6 2.45
1.5 - 20.02 2.31–2.65 2.475
2 - 25.47 2.35–2.69 2.52
2.5 - 37.25 2.4–2.75 2.56
3 - 20.27 2.48–2.84 2.65
Table 4. Parameters of antenna at different values of g2.
g2(mm)
S11 in
dB
Bandwidth
(GHz)
Resonant frequency
(GHz)
7.2 - 34.21 2.43–2.8 2.6
7.45 - 24.26 2.38–2.73 2.54
7.7 - 20.02 2.31–2.65 2.475
7.95 - 17.24 2.25–2.55 2.39
8.2 – – –
164 Page 4 of 10 Sådhanå (2021) 46:164
addition to the rectangular slot discussed in Case 2. Case 3
shows a return loss of - 16.30 dB at the resonant fre-
quency 2.42 GHz covering a bandwidth of 2.28–2.57 GHz.
To get better results in terms of return loss within ISM
band, Case 3 has been considered in which one more cir-
cular slot of radius 1.5 mm is added in addition to the two
rectangular slots of Case 3. Further, Case 4 depicts a return
(d)
2.0 2.2 2.4 2.6 2.8 3.0-35
-30
-25
-20
-15
-10
-5
0
Ret
urn
Loss
(dB)
Frequency (GHz)
skin brain three layer
(a) (b) (c)
Figure 3. Simulation of antenna. (a) Antenna inside skin layer using CST MWS software. (b) Antenna inside three layer using CST
MWS software. (c) Antenna inside brain layer using CST MWS software. (d) Comparison of simulated return loss characteristics of the
proposed antenna.
Table 5. Dielectric properties of human tissues at ISM band.
Human tissue
layer Permittivity
Conductivity (S/
m)
Density (kg/
m3)
skin 38.007 1.464 1020
fat 5.280 0.105 918
muscle 53.574 1.810 1040
Table 6. Performance of the proposed antenna in brain layer,
single skin layer and three layer phantom models.
S11 in
dB
Bandwidth in
GHz
Resonant frequency
(GHz)
Skin - 20.02 2.31–2.65 2.475
Brain - 30.61 2.35–2.68 2.51
Three
layer
- 17.04 2.24–2.56 2.38
Sådhanå (2021) 46:164 Page 5 of 10 164
loss of - 20.02 dB at the resonant frequency 2.475 GHz
covering a bandwidth of 2.31–2.65 GHz.
2.2 Parametric sweep with different r1 and g2
Figure 2c shows the change in return loss of antenna with
change in radius of circular slot in ground plane from
r1 = 0.5 to r1 = 3. The return loss of r1 = 1.5 is best suited
for the proposed antenna as its resonance frequency falls in
the desired bandwidth allocated to ISM band. Table 3
depicts the performance characteristics of the proposed
antenna with different values of radius of circular slot
embedded at the centre of ground plane. Moreover, fig-
ure 2d shows the change in return loss of antenna with
change in length g2 of bigger rectangular slot in ground
plane from g2 = 7.2 to g2 = 8.2. From table 4 it is clear that
return loss of g2 = 7.7 and its corresponding resonance
frequency is best suited for our desired ISM band.
3. Simulation set up of the proposed antenna
Figure 3 shows the simulation setup of the proposed
antenna. The proposed antenna has been simulated using
Computer Simulation Technology Microwave Studio
(CST MWS). Figure 3a shows the antenna inside single-
layer model of skin phantom with 4 mm skin layers at both
sides whereas, in figure 3b the antenna is simulated inside
three-layer model of skin, fat and muscle with height
4 mm, 4 mm and 8 mm respectively and in figure 3c the
antenna is simulated inside single-layer model of 4 mm
brain layers at both sides.
Figure 3d illustrates the simulated return loss charac-
teristic of the proposed antenna inside the brain layer,
single-skin layer and three-layer from which it is clearly
observed that in all the models, the antenna is resonating
at desired ISM band. There are minimal changes in the
return loss of these three models which shows that the
antenna is perfectly and evenly working in brain layer,
skin layer as well as in three layered phantoms. Table 5
shows the dielectric properties of these human tissues at
ISM band. Further, Table 6 shows the values of return
loss and bandwidth achieved by the proposed antenna
within brain layer, single skin layer and three-layer
phantom models.
3.1 Surface current distribution
Figure 4a shows the surface current distribution of the radi-
ating element and ground plane of the proposed compact
Figure 4. Surface current and SAR of the proposed antenna. (a) Surface current distribution on radiating element and ground plane.
(b) SAR value for 1-g averaged and 10-g averaged.
164 Page 6 of 10 Sådhanå (2021) 46:164
superstrate loaded slotted implantable antenna. This gives an
idea about those parts of antenna that are mostly responsible
for radiation. It can be observed that the current intensity is
maximumacross the feedlinewhich is attached to the radiating
patch and across a semi-circular slot embedded at the bottom
corner of the patch. Two rectangular slots and one circular slot
are etched from the ground plane to attain the property of the
defected ground structure. The current density is increased
near the edges of slots,whichmeans that the inserted slots play
a vital role to obtain the desired ISMbandwithout affecting the
bandwidth.
3.2 Specific absorption rate (SAR)
The impact of the proposed compact superstrate loaded
slotted implantable antenna on human tissue, described by
the SAR was also examined. SAR value depends on the
geometry of the human tissue, antenna positioning,
dielectric properties of tissue, transmitting input power and
spacing between the antenna and the human tissue. The
basic formula of SAR is given in equation (1).
SAR W/kgð Þ ¼ r� E2
qð1Þ
where r is the conductivity of tissue (S/m), E is root mean
square value of the electric field (V/m) induced in the tissue
and q is the tissue density (kg/m2). The American standard
for SAR analysis is used in this i.e. the SAR value averaged
over 1 g of tissue should be less than 1.6 W/kg. For vali-
dating the results of the proposed antenna, SAR (1-g
averaged and 10-g averaged) are calculated at the res-
onating frequency. For checking that if the antenna is
biocompatible inside the human body or not, the SAR
values for 1 W are shown in figure 4b. The SAR value for
1 g-averaged cubic tissue obtained for supply power of
1 W is 900 W/kg means a supply of less than 1.78 mW
should be applied to obtain a value of SAR below 1.6 W/kg
limit. Similarly, the SAR value for 10 g-averaged cubic
tissue obtained for supply power of 1 W is 82.1 W/kg
means a supply of less than 24.4 mW should be applied to
obtain a value of SAR below 2 W/kg limit.
Figure 5 shows the impedance versus frequency plot of
the proposed antenna within the range 2–3 GHz. A marker
Figure 5. Impedance vs frequency plot of proposed antenna. (a) Real part. (b) Imaginary part.
Sådhanå (2021) 46:164 Page 7 of 10 164
is shown to depict the resonating frequency of the proposed
antenna satisfying ISM band. The real part of impedance is
49.33 ohm as shown in figure 5a whereas the imaginary
part of impedance is - 6.02 ohms at the resonating fre-
quency as shown in figure 5b. These results clearly justify
the radiated behaviour of antenna with perfect impedance
matching of approximately 50 ohms and negligible reactive
power, thus making the proposed antenna suitable for ISM
band applications.
Figure 6a depicts the simulated gain vs frequency plot of
antenna in single skin layer. A peak gain of - 17.08 dBi at
2.475 GHz is reported. Figure 6b and figure 6c illustrate the
simulated E-plane and H-plane polar plots in relation to co-
polarization and cross-polarization at phi = 90� and phi =
0� of the proposed antenna, respectively. The E-plane
pattern is bidirectional whereas H-plane pattern is omni-
directional in nature.
Figure 7 shows the testing of antenna using Vector
Network Analyzer (VNA) and comparison of simulated
and measured return loss of the proposed antenna. The
return loss of the fabricated antenna is measured using
Agilent E5071C vector network analyser available in
Antenna Research Laboratory, Department of Electronics
and Communication Engineering, Thapar Institute of
Engineering and Technology, Patiala as shown in fig-
ure 7a. To test the antenna, a homogenous phantom of skin
mimicking liquid (made using 50% water and 50% sugar)
is made with approximately the same electrical properties
as that of skin whose recipe is illustrated in [8]. This
phantom is inserted inside a container of size
150 9 100 9 50 mm3 and filled such that the antenna can
be easily dipped inside the liquid phantom. Figure 7b
shows the comparison of simulated and measured return
loss of the proposed antenna inside a single layer skin
phantom. Figure 7b clearly depicts a close agreement
between the simulated and measured results of the pro-
posed antenna at ISM band inside skin except for some
small differences in return loss and bandwidth as illus-
trated in Table 7. Table 8 illustrates the comparison of
performance characteristics of the proposed antenna with
recently reported literature. Bandwidth, peak gain, SAR
(1 g-averaged and 10 g-averaged) and volume factor are
some of the performance measures used for comparing the
proposed antenna with previous literature. Volume factor
of antenna is the ratio of bandwidth (kHz) to the area of
antenna (mm3) as depicted in equation (2) [21]. Compar-
ing this parameter with the previously reported literature it
is clear that the proposed antenna is much better.
Volume factor VFð Þ ¼Bandwidth in kHzð Þ=Antenna area mm3
� � ð2Þ
4. Conclusion
In this proposed work, a compact implantable antenna
of patch size 6.2 9 4.5 mm2 and peak gain
- 17.08 dBi is made for biotelemetry applications at
(b)
(c)
2.0 2.2 2.4 2.6 2.8 3.0-20
-15
-10
-5
0
Gai
n (d
Bi)
Frequency (GHz)
Gain
030
60
90
120
150180
210
240
270
300
330
cross polar co polar
030
60
90
120
150180
210
240
270
300
330
cross polar copolar
(a)
Figure 6. Radiation pattern of proposed antenna. (a) Simulated
gain vs frequency pattern of the proposed antenna. (b) Simulated
co-polarization and cross-polarization at E-plane for phi = 90�.(c) Simulated co-polarization and cross-polarization at H-plane for
phi = 0�.
164 Page 8 of 10 Sådhanå (2021) 46:164
ISM band. Slotting strategy is utilized both in patch as
well as ground plane because of which an appreciable
bandwidth of 13.7% is accomplished. The measured
results obtained from the in-vitro testing of fabricated
antenna done inside skin phantom are in close agree-
ment to the simulated results with a little yet satis-
factory variation. SAR value for 1-g and 10-g averaged
cubic tissue is considered for the security of patient
from unfavourable impact of radio frequency radiations
on human body. Table 8 gives a point to point corre-
lation of this work with the ongoing literature in terms
of performance measures such as SAR, peak gain,
bandwidth and volume factor which shows that the
presented antenna is quite adequate for
implantable devices and circuits.
(a) (b)
2 2.2 2.4 2.6 2.8 3
-30
-25
-20
-15
-10
-5
0
5
Ret
urn
loss
(dB)
Frequency (GHz)
Simulated Measured
Figure 7. Testing of antenna and comparison of simulated and measured return loss. (a) Fabricated antenna testing inside skin
mimicking liquid. (b) Comparison of simulated and measured return loss of the proposed antenna in skin.
Table 7. Simulated and measured return loss and bandwith of the
proposed antenna.
S11 in dB Bandwidth in GHz
Skin (simulated) - 20.02 2.31–2.65
Skin (measured) - 29.28 2.22–2.61
Table 8. Comparison of performance of proposed antenna with recent literature.
Refs.
Dimensions
(mm3)
Bandwidth
(|S11| B - 10 dB) at
ISM band
Peak
gain
(dBi)
SAR (1 g-average)
at 1 W power
SAR (10 g-average)
at 1 W power
Volume
factor
Superstrate
layers
[8] 27.5 9 21 9 1.6 12.57% - 27.46 – – 335 Nil
[9] 10 9 10 9 1.27 10.84% - 21 710.65 84.6 826 Single
[10] 16.5 9 16.5 9 2.54 4.4% - 9 292 – 159 Single
[23] 10 9 15 9 2 – - 16.3 – – – Both sides
[27] 22 9 16 9 1.27 1.6% - 19.5 2.15 9 10-3 – 89.5 Nil
This
work
10.2 9 8.61 9 1.92 13.7% - 17.08 900 82.1 2016 Both sides
Sådhanå (2021) 46:164 Page 9 of 10 164
References
[1] Shults M C, Rhodes R K, Updike S J, Gilligan BJ and
Reining WN 1994 A telemetry-instrumentation system for
monitoring multiple subcutaneously implanted glucose sen-
sors. IEEE Transactions on Biomedical Engineering 41:
937–942
[2] Buchegger T, Obberger G, Reisenzahn A, Hochmair E,
Stelzer A and Springer A 2005 Ultra-wideband transceivers
for cochlear implants. EURASIP Journal on Applied SignalProcessing 2005: 3069–3075
[3] Gosalia K, Lazzi G and Humayun M 2005 Investigation of a
microwave data telemetry link for a retinal prosthesis. IEEETransactions on Microwave Theory and Techniques 52:
1925–1933
[4] Guillory K S and Normann R A 1999 A 100-channel system
for real time detection and storage of extracellular spike
waveforms. Journal of Neuroscience Methods 91: 21–29[5] Merli F, Bolomey L, Zurcher J F, Corradini G, Meurville E
and Skrivervi A K 2011 Design, realization and measure-
ments of a miniature antenna for implantable wireless
communication systems. IEEE Transactions on Antennasand Propagation 59: 3544–3555
[6] Kiourti A and Nikita K S 2012 2012 A review of
implantable patch antennas for biomedical telemetry: chal-
lenges and solutions [wireless corner]. IEEE Antennas andPropagation Magazine 54: 210–228
[7] Cho Y and Yoo H 2016 Miniaturised dual-band
implantable antenna for wireless biotelemetry. ElectronicsLetters 52: 1005–1007
[8] Sukhija S and Sarin R K 2017 Low-profile patch antennas for
biomedical and wireless applications. Journal of Computa-tional Electronics 16: 354–368
[9] Ahlawat S, Srivastava G and Kumar G 2019 Design of skin
implantable radiator with capacitive and CSRR loadings for
ISM band applications. International Journal of InformationTechnology 12: 1–10
[10] Liu C, Guo Y X and Xiao S 2012 Compact dual-band
antenna for implantable devices. IEEE Antennas and Wire-less Propagation Letters 11: 1508–1511
[11] Liu W C, Chen S H and Wu C M 2008 Implantable broad-
band circular stacked PIFA antenna for biotelemetry com-
munication. Journal of Electromagnetic Waves andApplications 22: 1791–1800
[12] Soontornpipit P, Furse C M and Chung Y C 2004 Design of
implantable microstrip antenna for communication with
medical implants. IEEE Trans Microwave Theory Techn.52: 1944–1951
[13] Lee S, Seo W, Ito K and Choi J 2011 Design of an implanted
compact antenna for an artificial cardiac pacemaker system.
IEICE Electron Express 8: 2112–2117[14] Liu W, Yeh F and Ghavami M 2008 Miniaturized
implantable broadband antenna for biotelemetry communi-
cation. Microw. Opt. Technol Lett. 50: 2407–2409
[15] Lee C M, Yo T C and Luo C H 2007 Compact broadband
stacked implantable antenna for biotelemetry with medical
devices. Electronics Lett. 43: 660–662[16] Karacolak T, Cooper R and Topsakal E 2009 Electrical
properties of rat skin and design of implantable antennas for
medical wireless telemetry. IEEE Trans Antennas Propag.57: 2806–2812
[17] Basir A, Bouazizi A and Zada M et al 2018 A dual-band
implantable antenna with wide-band characteristics at MICS
and ISM bands. Microw. Opt. Technol. Lett. 60: 2944–2949[18] Kim J and Rahmat-Samii Y 2014 Implantable antennas
inside a human body: simulations, designs, and characteri-
zations. IEEE Trans Microwave Theory Techn. 52:
1934–1943
[19] Bakogianni S and Koulouridis S 2015 An implantable pla-
nar dipole antenna for wireless MedRadio band bioteleme-
try devices. IEEE Antennas Wireless Propag. Lett. 15:
234–237
[20] Lee J H and Seo D W 2019 Compact and tissue-insensitive
implantable antenna on magneto-dielectric substrate for
wireless biotelemetry. Journal of Electromagnetic Wavesand Applications 33: 2339–2461
[21] Ikonen P M T, Rozanov K N, Osipov A V, Alitalo P and
Tretyakov S A 2006 Magnetodielectric substrates in antenna
miniaturization: potential and limitations. IEEE TransAntennas Propag. 54: 3391–3399
[22] Abdelrahman E M, Ali H M and Mohammad S S 2017
Superstrate loaded miniaturized patch for biomedical teleme-
try. OMicrow Opt. Technol. Lett. 59: 1212–1218[23] Aslam B, Khan U H, Azam M A, Amin Y, Loo J and
Tenhunen H A 2017 A compact implantable RFID tag
antenna dedicated to wireless health care. InternationalJournal of RF and Microwave Computer-Aided Engineering27: e21094
[24] Kovar S, Spano I, Gatto G, Valouch J and Adamek M 2017
SAR evaluation of wireless antenna on implanted cardiac
pacemaker. Journal of Electromagnetic Waves andApplica-tions 31: 627–635
[25] Zhang Y, Liu C, Zhang K, Cao H and Liu X 2019 Design
and in-vivo testing of a low-cost miniaturized capsule
system for body temperature monitoring. InternationalJournal of RF and Microwave Computer-Aided Engi-neering 29: e21793
[26] Zhang H, Li L, Liu C, Guo Y X and Wu S 2017 Miniaturized
implantable antenna integrated with split resonate rings for
wireless power transfer and data telemetry. Microwave andOptical Technology Letters 59: 710–714
[27] Yeap K, Voon C, Hiraguri T and Nisar H 2019 A compact
dual-band implantable antenna for medical telemetry. Mi-crowave and Optical Technology Letters 61: 2105–2109
[28] Das S and Mitra D 2020 Design of a compact circular
polarized implantable ring slot antenna for biomedical
applications. Electromagnetics 40: 1–10
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