This document describes the design and simulation of a tapered slot antenna (TSA) array for underwater communication in the microwave band. A single TSA element was designed on an FR4 substrate with an exponentially tapered slot fed by a microstrip line. The design was then expanded into 1×2, 1×4, and 2×4 element arrays. Simulation results showed the single element achieved over 55% impedance bandwidth with a peak gain of 4.82 dBi. The 1×2, 1×4, and 2×4 arrays achieved higher peak gains of 6.85 dBi, 9.65 dBi, and 10.75 dBi, respectively, while maintaining over 50% bandwidth and radiation efficiency above

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A Broadband High Gain Tapered Slot Antenna for Underwater Communication
in Microwave Band
Article in Wireless Personal Communications · January 2021
DOI: 10.1007/s11277-019-06633-2
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2. Vol.:(0123456789)
Wireless Personal Communications
https://doi.org/10.1007/s11277-019-06633-2
1 3
A Broadband High Gain Tapered Slot Antenna
for Underwater Communication in Microwave Band
Permanand Soothar1
· Hao Wang1
· Badar Muneer2
· Zaheer Ahmed Dayo3
·
Bhawani Shankar Chowdhry2
© Springer Science+Business Media, LLC, part of Springer Nature 2019
Abstract
A broadband high gain Tapered slot antenna array for under water communication is
presented in this paper. The procedure to design the unit element antenna is followed by
applying a linear tapered array-slot structure to the conventional Vivaldi antenna; hence
the bandwidth, gain and radiation efficiency of the antenna are improved. The proposed
antenna array is designed on the low-cost FR4 epoxy substrate material with value of die-
lectric constant 𝜀r = 4.4, and loss tangent 𝛿 = 0.02. The reduction of the feed line width
and location adjustment is used to expand the impedance bandwidth of the proposed
antenna. Moreover, the single antenna element is expanded to1 × 2,1 × 4 and 2 × 4 to form
an antenna array respectively. The dimensions of the developed array antenna are satisfy-
ing the proper impedance matching. The simulated reflection coefficient results confirm
that the proposed antenna array achieves an impedance bandwidth of above 55% obtained
at 10 dB return loss, the peak realized gain of 10.75 dBi and radiation efficiency of more
than 90%. The measured results show a good agreement and hence making the designed
antenna array appropriate to work in the underwater communication band.
Keywords TSA array · Broadband · High gain · Radiation efficiency · Underwater
communication
* Badar Muneer
badar.muneer@faculty.muet.edu.pk
Permanand Soothar
permanand.soothar@hotmail.com; permanand.soothar@njust.edu.cn
Hao Wang
haowang@njust.edu.cn
Zaheer Ahmed Dayo
dayo.zaheer@hotmail.com
Bhawani Shankar Chowdhry
bhawani.chowdhry@faculty.muet.edu.pk
1
School of Electronic and Optical Engineering, Nanjing University of Science and Technology,
Nanjing 210094, China
2
Mehran University of Engineering and Technology, Jamshoro 76062, Pakistan
3
College of Electronic and Information Engineering, Nanjing University of Aeronautics
and Astronautics, Nanjing 211100, China

3. P. Soothar et al.
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1 Introduction
A tapered slot antenna (TSA) is a special class of antennas which can be used in differ-
ent applications such as Ultra-Wideband (UWB) [1], cognitive radio [2], medical imag-
ing [3, 4], satellite communications, large ships [5] and GPR system [6] etc. TSA antenna
was firstly introduced by Gibson [7]. It possessed the numerous advantages of low profile,
compact, planar structure, ease of fabrication, compatibility with microwave integrated cir-
cuits, high efficiency, directional radiation pattern, broadband impedance bandwidth and
high gain realization [8, 9]. All these properties, specially the low-profile, planar structure
and compactness are essential to have when it comes to underwater wireless communica-
tion. Since past years researchers have published more papers on antenna design layout,
to improve the array performance parameters of each element such as impedance band-
width, gain, radiation efficiency, radiation pattern in the operating frequency. Increasing
the bandwidth of the antenna elements can influence the radiation pattern [10]. The design
of the TSA array elements depends on its antenna length, width and the ground extension
parameters.
Tapered slot line is flared to provide an aperture for microwave radiation in free space,
a flared slot line can be provided with the aid of a transition line, an elliptical curve, and
exponential curve equation. The combination of two curves has some specific users to get
the desired characteristics of the antenna. TSA produce the end-fire travelling wave hence
the phase velocity and guide wavelength which are liable to the substrate thickness, taper
rate and dielectric constant. The width, length and the taper profile of TSA involve the
radiation characteristics of an antenna and its gain is proportional to the L∕𝜆g [11, 12]. It is
etched on the thin metal layer placed on the substrate. It can be fed through different feed-
lines i.e., stripline, coplanar waveguide, a microstrip line or coaxial feedline. The micro-
strip and strip lines feeding of TSA can work over the wide bandwidths and high gain. It
should have a perfect impedance matching when it achieves the broad bandwidth by adjust-
ing the feedline location connected with the cavity stub and the slotline [13].
There has been growing demand to the underwater communication technology from the
industry and the scientific community, which is due to the broad range of applications like
coastline protection, surveillance, off-shore oil and gas field monitoring, underwater envi-
ronmental observation for exploration, oceanographic data collection. It involves enough
bandwidth for high data rates, which may be required for real-time video exchange among
the underwater bodies that is not possible with acoustic waves.
In underwater communications, the three widely used communication technology for
underwater applications are acoustics signals, optical signals and Electromagnetic (EM)
signals [14]. In the EM wave, the Ultra-wideband (UWB) and broadband antennas are
radio transmission innovation which involves a wide bandwidth, i.e. > 500 MHz or possi-
bly 20% of the Centre frequency [15], is additionally a progressive methodology for short-
range high-bandwidth remote communication.
Xu et al. [16], have presented a work on a wideband monopole antenna for Blue-
tooth and UWB application, utilized lower pass Band-U formed parasitic strips recipro-
cally close to bolster line on a FR4 substrate with measurements of (18 × 32 × 0.8) mm3
,
examined the reflection coefficient by changing length and feed crevice. The peak gain
at Bluetooth band of 1.6 dB. Other studies have been proposed by Chang et al. [17], in
which the inverted F antenna for a 313 GHz short range (< 10 m) UWB indoor, remote
communication has been proposed. A planar monopole is top stacked with a rectangular
patch connected to two rectangular plate, one shorted to ground and other suspended on

4. A Broadband High Gain Tapered Slot Antenna for Underwater…
1 3
an FR4 substrate with a measurement of (20 × 10 × 7) mm3
. Another work on a differen-
tial bolstered magneto-dielectric dipole has been proposed in [18], which mainly focuses
on unidirectional radiation design and an increase of 8.25 ± 1.05 dBi on a Doored 5870
substrate with a measurement of (65 × 65 × 9.8) mm3
. However, impedance transmission
capacity of 114% for frequencies from 2.95 to 10.73 GHz range. Besides, the radiation
pattern in E and H planes are all around carried on up to 9.4 and 8.9 GHz, individually,
after which side flaps show up because of the high request modes radiation. Moreover,
Arash et al. [19], a couple line nourished planar, (patch antenna) which has a double
band score with two coordinated monopoles that endeavors to incorporate the UWB
innovation with Bluetooth and Global System for Mobile Communications (GSM) at
900 MHz has been proposed. Another author Kwai et al. [20, 21], has discussed a mag-
neto electric dipole for UWB application that can be effortlessly imprinted on Duroid
5880 substrate for 60 GHz frequency. In this a level tie electric dipole with an imped-
ance transmission capacity of 110%, with SWR ≤ 2 was broke down from 3.08 to 10.6
GHz. Li et al. [22], have presented UWB antennae in light of time domain or frequency
domain on one side low gain and high gain on the other side. Li Dissected ringing,
bunch delay, signal loyalty and separation parameters. A coordinated Bow tie antenna
outlined by Abdou et al. [23], have demonstrated, a RL of − 16 dB at 433 MHz which
implies that more than 95% of the force is transmitted in air and the reenactment intro-
duces a sharp valley at low frequencies of 154 MHz with a high esteem RL of − 43
dB and data transfer capacity of 90MHz in undersea, this antenna is completely water-
proofed in paste. Moreover, our work presented in this paper, have achieved the return
loss (RL) about − 61 dB at 6.1 GHz resonant frequency, in order to meet the application
for microwave band, a simulation design of higher order antenna array with maximum
directivity and wide bandwidth has been presented which is essential to obtain for a
long distance communication with high data rates.
Few other authors have presented work in [24], on the EM wave propagation through
seawater at MHz frequencies, Shaw conducted diverse class tests in a fiber tank with
dipole, circle, two-fold circle and collapsed circle antennas. Another study conducted
by Waheed et al. [25], on very low frequency (VLF) antenna for undersea interchanges.
The authors have utilized copper wires which were rewound like a transformer center
in bearing. Besides a low power regulated and speaker circuit was intended for short
separation interchanges between two submarines. Hector et al. [26], outlined a cradle
for decreasing the transmission misfortune in submerged interchanges. Consequently, the
reflection coefficient observed was − 25.98 dB in 2.38 GHz (without spread) and − 34.25
dB in 2.58 GHz (with glass cover). When glass spread is utilized the antenna transmis-
sion capacity diminished from 100 MHz to 70 MHz, because of the permittivity of glass.
In this manuscript, design and development of 2 × 4 antenna array for underwa-
ter microwave band application have been studied. We have worked on total antenna
array performance by designing and implementing the Wilkinson power divider and its
characteristics of TSA with different antenna array arrangement resulted in impedance
bandwidth and high gain. The strip line is etched on the top surface of the glass epoxy
FR4 substrate and a ground plane. Moreover, the radiation characteristics and imped-
ance bandwidth of the proposed antenna array have been improved as compared to a
single element. The proposed antenna array (single element, 1 × 2, 1 × 4 and 2 × 4) has
obtained the impedance bandwidth of more than > 50% with the peak realized gain of
4.82 dBi, 6.85 dBi, 9.65 dBi and 10.75 dBi and radiation efficiency of 90% at the oper-
ating frequency of 6 GHz. This antenna possesses the compact dimension of over all

5. P. Soothar et al.
1 3
four elements arrays are (1.334𝜆 × 1.612𝜆 × 0.016𝜆) mm3
, the wavelength is the mini-
mum frequency of the desired microwave band and are satisfying the better radiation
efficiency, impedance bandwidth and peak realized gain. Hence, we conclude that this
proposed design of an antenna array is well suited for under water communication
microwave band applications.
This paper consists of five sections: Sect. 1 is introduction of a proposed antenna,
Sect. 2 discusses the design of simulation and fabrication of single element and impedance
matching, Sect. 3 gives simulated results and analysis, Sect. 4 discusses the performance
analysis of (1 × 2, 1 × 4 and 2 × 4) element array finally the Sect. 5 gives the conclusion.
2
Design of the Antenna Element Array and Description
2.1 Designing and Fabrication of Single Unit
Designing and fabrication of TSA are shown in Fig. 1a, b. The proposed antenna consists
of a substrate, feedline, and the ground plane and cavity circle. The feed line is placed on
the top of the dielectric substrate and cavity circle is used with slot line and the linear taper
profile. Moreover, tapered profile structure can be classified into two categories: substrate
parameters and antenna element parameters, which can be subdivided into the stripline/
slotline transition, the tapered slot, and radius of the circular slotline cavity [27, 28].
The stripline/Slotline transition is specified by strip line width (w1) and slotline width
(wsl). The exponential taper profile is defined by the opening rate R and two points
P1(x1, y1) and P2(x2, y2) [29]. TSA taper length has been selected as 0.666𝜆◦ and the open-
ing rate aperture width of proposed antenna is chosen as 0.333𝜆◦ at the lowest operating
band, where 𝜆◦ is the free space wavelength calculated at 4 GHz to work as a travelling
wave antenna [30, 31]. The proposed antenna dimensions are providing efficient radiation
from the TSA in (4–8 GHz). The linear exponentially tapered can be determined by:
where
(1)
y = c1eRx
+ c2
c1 =
y2 − y1
eRx2 − eRx1
c2 =
y1eRx2 − y2eRx1
eRx2 − eRx1
Fig. 1 a Side view and b top view geometry of proposed antenna

6. A Broadband High Gain Tapered Slot Antenna for Underwater…
1 3
The tapered Tsl is (x2 − x1) and aperture height H is 2(y2 − y1) + wsl. In the limiting case
where opening rate R approaches zero, the exponential taper results in a linearly tapered
slot antenna (LTSA) for which the taper slope is given by s◦ = (y2 − y1)∕(x2 − x1). For the
exponential taper defined by (1), the taper slope s changes continuously from s1 to s2, where
s1 and s2 are the taper slope at x = x1 and x = x2 respectively and s1 s s2 for R 0. The
taper flare angle is defined by 𝛼 = tan−1
s. The flare angles, however, are interrelated with
and defined parameters, i.e., H, Tsl, R and wsl. The parameters related to the stripline feed-
ing and circular slotline cavity shown in Fig. 1a are as follows in Table 1.
The following figures show the side and top view geometry of the tapered slot antenna.
However, the array design and impedance matching of proposed antenna structure is
described in the below section.
Figure 1 shows the optimized values of Vivaldi antenna geometry are provided in the
Table 1. The parameters: Width (W), length (L) thickness (h) of substrate and patch
remains same for the designed antenna (Fig. 2).
2.1.1 Vivaldi Antenna Array
For operating frequency within the underwater communication microwave band spectrum
the part of the planar Vivaldi antenna structure relevant to the frequency works. However,
the width (w) of this part is very near to the corresponding wavelength, hence electro-
magnetic wave is radiated out of the antenna. Whereas, the operating frequency changes,
the radiation pattern region of proposed antenna also changes accordingly. consequently,
the electrical size of operational region in the Vivaldi antenna remains constant across
the operational frequency band. Besides, input impedance and radiation pattern may also
maintain approximately constant across the entire operational frequency band of spectrum.
As a result, the Vivaldi antenna possessed the wideband characteristic [32].
Moreover, the TSA has some advantages as a radiator for phased arrays, imaging arrays,
underwater communication microwave spectrum and integrated active antennas because
of the broad impedance bandwidth, symmetrical radiation pattern, and planar structure. In
general, mutual coupling produces several effects including impedance mismatch, scanning
blindness, and distortion of radiation patterns. The horizontal and vertical mutual coupling
between two adjacent elements was investigated by calculating the transmission coefficient
(S21 and S31).
Table 1 Geometric parameters TSA parameters Optimized
dimensions
(mm)
1. Patch, width (W) 90
2. Patch, length (L) 69
3. Thickness (h) 1.2
4. Feed line length (l1) 32.5
5. Feed line width (w1) 2.38
6. The diameter of the circular slotline cavity (r) 10
7. The width of slotline (wsl) 3
8. The length of slotline (lsl) 10.3

7. P. Soothar et al.
1 3
2.2 Impedance Matching
In order to get a transition that has low S11 over a broad frequency band and the imped-
ance of the slot line and strip line must be matched to each other to reduce the reflec-
tion. To achieve an impedance values up to 50𝛺, the characteristics impedance of slot-
line increases with the increase of the slot width, therefore, suitable width of slotline
should be chosen to match with 50𝛺 input. The strip line feed used in a TSA is con-
nected directly to the transmitter or receiver or fed by a coaxial attached to an SMA
connector, the slotline width, guided wavelength, and strip width is calculated by using
formulas mentioned in [33]. Distance between the antennas, dimensions of the feedline
and guided wavelength plays a major role on the performance of each antenna element.
Fig. 2 a, b Printed Feedline connection with SMA connector and measured at Anechoic chamber c fabrica-
tion process of proposed antenna

8. A Broadband High Gain Tapered Slot Antenna for Underwater…
1 3
2.3 Design of Broadband Wilkinson Power Divider
The power divider is needed to feed the array design of 1 × 2 elements. The power divider
signals are used to balance the phases and amplitudes from the other two ports [34, 35].
Firstly, the two output ports and the input port must be matched with the impedance
characteristic, only then the power divider can be directly connected with the proposed
antenna. Figure 3a, b represent the power divider of insertion loss (S21 and S31) and the
simulated return loss (S11) at the operating band from 4 to 8 GHz, the Fig. 3 indicates that
the return loss is below 10 dB have good bandwidth which has reached 57% at the resonant
frequency of 6 GHz and the two output ports have better power divider level with insertion
loss of 3.8 dB.
2 × 4 Vivaldi antenna array has been designed to operate in the 4–8 GHz C band fre-
quency spectrum. Moreover, spacing between two adjacent antenna elements is set as
0.5𝜆◦.
3
Simulation Results and Analysis
3.1 Return Loss, S11
The simulated result of a unified single element is shown in the following Fig. 4. It has
been observed, that the relative bandwidth at minimum return loss of 10 dB, and 15 dB is
obtained as 47.4% and 28.7%. In addition, maximum return loss is observed as 61 dB at the
resonant frequency of 6.1 GHz.
All these results have been observed and tested using Agilent PNA-X-N5224A network
analyzer (VNA). However, the peak realized gain of unit element is 4.82 dBi at the reso-
nant frequency of 6.1 GHz.
3.2 Voltage Standing Wave Ratio (VSWR)
Voltage standing wave ratio results of a single element are presented in Fig. 5. It clearly
shows that the value of VSWR for this antenna is 1.0 at the resonant frequency of 6.1
Fig. 3 a, b Simulated return loss (S11) and insertion loss (S21 and S31) of Wilkinson power divider

9. P. Soothar et al.
1 3
GHz. It is also observed from the plot that, for the frequency value from 4.7 to 7.9 GHz
the VSWR value remains less than 2. Figure 6 shows the radiation efficiency of the pro-
posed antenna is 84%.
Fig. 4 Variation of return loss
with the frequency of the pro-
posed slot antenna
Fig. 5 Variation of VSWR vs.
frequency of tapered slot antenna
Fig. 6 Radiation efficiency of
tapered slot antenna

10. A Broadband High Gain Tapered Slot Antenna for Underwater…
1 3
3.3 Radiation Pattern
The 2-dimensional radiation pattern plots in both azimuth and elevation plane are shown in
Fig. 7a.
It is observed from the Fig. 7b that the proposed antenna gain is 4.82 dBi at the resonant
frequency of 6.1 GHz. The antenna beam points towards the 90-degree direction which is
expected for an endfire type of antenna. Almost all antenna radiates equally in the other plane.
Figure 8 shows the surface current distribution of single element tapered slot, the electric field
at 3.02 GHz with no phase shift is observed at the surface.
Fig. 7 a, b An isotropic radiation pattern and peak realized gain
Fig. 8 J Surface current distribu-
tion of the proposed antenna

11. P. Soothar et al.
1 3
4
Array Elements Analysis
4.1 Performance Analysis of Dual Element
Designing of TSA array is etched on a glass epoxy FR4 substrate (𝜀r = 4.4) with a same
configuration of the single element omit that the impedance matching transformer is
utilized for broadband impedance bandwidth as depicted in Fig. 9a and it covers the
desired microwave band. The impedance of feedline characteristics width and the
adjustment of the distance between elements of the antenna have the half of the wave-
length 0.5𝜆◦ of the operating frequency. The distance between element shouldn’t overlay
with each other because they will interface together and degrade the performance of
transition. In order to observe the array spacing elements, the distance of the two ele-
ments design and the feeding power divider is very important for proper matched the
impedance techniques and achieve the better results and radiation efficiency.
The dual element of the proposed antenna has been observed from the simulated
results that the relative bandwidth of minimum return loss of 10 dB, 15 dB and 20 dB is
obtained as 57.33%, 46.88% and 28.2% at the resonant frequency of 6 GHz as shown in
the Fig. 9a. From the figure it is observed that the impedance bandwidth of 57.3% or has
been achieved at 10 dB return loss.
VSWR results are presented in Fig. 9b. It shows that the value of voltage standing
wave for this antenna is 1.0 at the resonant frequency of 6 GHz. It is also observed from
the figure that, for the frequency value from 4.25 to 7.9 GHz the VSWR value remains
less than 2.
Moreover, the peak realized gain of the dual element has been observed as 6.85 dBi
at the resonant frequency of 6 GHz as shown in the Fig. 10a. However, the efficiency is
improved than the single element which is 94%, it means the performance of the radia-
tion efficiency is better than the unit element design as shown in the plot Fig. 10b.
From the Fig. 11a, shows the antenna directivity with the variation of angle (Phi),
it can clearly observe the wide beam of an antenna at above 6 dBi and the right side
Fig. 11b represented that the radiation pattern of elevation and azimuth plane radiated
at (0◦
–90◦).
Fig. 9 a, b Variation of return loss and VSWR with the frequency of the proposed slot antenna

12. A Broadband High Gain Tapered Slot Antenna for Underwater…
1 3
4.2 Performance Analysis of1 × 4 Array Elements
At the feed port of four element array, the two power dividers were shunted together to
make the array matched at 50𝛺. The spacing between the two adjacent single elements is
0.5𝜆◦ with an operating frequency of 6 GHz. The performance of two antenna elements has
been analyzed and connected with the aid of four-way power divider. First, we designed
the structure of power divider with four-way ports of 50𝛺 with single output etched to each
antenna element and achieve the proper impedance matching of the antenna.
To achieve the proper matching, the glass epoxy FR4 substrate material and thickness of
the single element has been chosen. As illustrated in Fig. 12a of the minimum return loss
of the 1 × 4 array element design, the fractional bandwidth of 55% the proposed antenna
has been achieved the desired microwave band.
Moreover, fractional bandwidth is calculated at the lower and upper frequency (4.5–7.8)
GHz as measured at maximum return loss of 10 dB at the resonant frequency of 7.2 GHz.
The observed impedance bandwidth at 3.4 GHz shows better performance than a single
and dual element. The bandwidth of array performance covers the wide bandwidth at C
Fig. 10 a, b Variation of realized gain and the efficiency with the frequency of the proposed slot antenna
Fig. 11 a, b The radiation pattern of E H plane and directivity of the proposed antenna

13. P. Soothar et al.
1 3
band (4–8) GHz and hence this antenna makes it appropriate to work for the underwater
communication. Considering the Fig. 12b, the value of VSWR is observed less than 2 from
the 4.45 to 7.90 GHz frequency range. It’s clearly observed form the plot that the antenna
is perfectly matched.
As depicted in the Fig. 13a, b, observed the gain and radiation efficiency of the array.
The plot Fig. 13a clearly shows the peak realized gain of an antenna array design is 9.65
dBi at the desired frequency. The performance of the radiation efficiency of the proposed
antenna array is shown in the Fig. 13b, which is same as unit element achieved at 84%. As
shown in Fig. 14a, b the directivity and radiation pattern of the array design elements.
4.3 Performance Analysis of 2 × 4 Array Elements
The broadband array antennas have different array pattern in the frequency of operation.
The broadband antennas will effect on the total array performance. Larger the width will
impact on the larger feeding line space among the elements. It will lead higher side lobe
level, even grating lobe, especially for higher frequency. Grating lobe can be occurred when
the distance of an antenna elements is more than one wavelength of its working frequency.
Fig. 12 a, b Variation of return loss and VSWR with the frequency of the 1×4 array element
Fig. 13 a, b Variation of the realized gain and radiation efficiency with a frequency of the array antenna

14. A Broadband High Gain Tapered Slot Antenna for Underwater…
1 3
The design performance of 2 × 4 elements has been observed from the 1 × 4 element
arrays. We used the same dimensions of shunted series 1 × 4 elements and have same sub-
strate FR4 epoxy material with thickness. The optimized power dividing feeding network
and spacing among elements array have been achieved the proper results under the desired
band. The space between the elements has been occurred 0.5𝜆◦ of the operating frequency
of 6 GHz.
As illustrated in the Fig. 15, the variation of return loss with the desired frequency band,
the final 2 × 4 array antenna is achieved at the multiple bands in the operating C band, it
has been resonated at three different frequency bands and simulated at the maximum return
loss of 10 dB. The array antenna has been resonated three different values of 4.5 GHz
(4.3–4.75) GHz, 5.4 GHz (5.3–6.4) GHz and 7.35 GHz (6.8–7.7) GHz as the maximum
return loss of 29.3 dB, 40 dB and 35.4 dB. The radiation efficiency has been observed upto
61% of the proposed antenna element array.
The peak realized gain of proposed array antenna design has been calculated from each
resonated values of 4.5 GHz at 7.58 dBi, 5.4 GHz at 8.56 dBi and 7.35 GHz at 10.75 dBi
of the gain as shown in the Fig. 16. The maximum peak realized gain of proposed antenna
array has been reached at 10.75 dBi.
Fig. 14 a, b Directivity and radiation pattern of proposed array1 × 4 element antenna
Fig. 15 Variation of S11 param-
eter with frequency of the array
antenna

15. P. Soothar et al.
1 3
5 Conclusion
In this paper, the authors designed a 2 × 4 TSA array for under water communication.
The proposed structure of an antenna consists of the substrate, patch, ground plane and
feeding network. Simple and an effective feeding technique i.e. stripline feed has been
used which resulted in an enhanced impedance bandwidth of more than 50% at a reso-
nant frequency of 6 GHz, peak realized gain of 10.75 dBi and the radiation efficiency is
more than 90%. The simulation and measured results have been analyzed and validated
by using simulation software Ansoft HFSS and anechoic chamber. Based on the analysis
and discussion presented in the paper, the optimum results of return loss, VSWR, gain
and radiation efficiency proved that this designed of an antenna is suitable for underwa-
ter communication microwave band applications.
Acknowledgements Funding was provided by Higher Education Commision, Pakistan (Grant No. NRPU
#6786).
Compliance with Ethical Standards
Conflict of interest The authors declare that there is no conflict of interest regarding the publication of this
article.
Ethical approval This article does not contain any studies with human participants or animals performed by
any of the authors.
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Publisher’s Note Springer Nature remains neutral with regard to jurisdictional claims in published maps and
institutional affiliations.
Permanand Soothar was born in Sindh, Pakistan. He received the B.E
and M.E degrees in Electronic and Telecommunication Engineering
from Mehran University of Engineering and Technology (MUET),
Jamshoro, Sindh Pakistan, in 2007 and 2012, respectively. During M.E.
program he was awarded European Commission Scholarship under the
Erasmus Mundus “Mobility for Life” project in the field of Telecom-
munication and Wireless Technologies, Innovative Communication
Technologies and Entrepreneurship (ICTE) at the Center of Tele Infra-
structure Aalborg University, Copenhagen Denmark since 2010 to
2011. Besides, Mr. Soothar is working as a faculty member in the
department of Electronics Engineering, MUET Jamshoro Since 2015.
Currently, He is pursuing the Ph.D degree under the supervision of Pro-
fessor Hao Wang at the School of Electronic and Optoelectronic Engi-
neering, Nanjing University of Science and Technology (NJUST), Nan-
jing, P.R. China. His research interests include planar microstrip patch
antennas, Ultra-wideband antennas, Millimeter-wave antennas, 5G
communication antennas, Gap waveguide technology, satellite commu-
nication system, dual polarization slotted waveguide antennas and array.

18. A Broadband High Gain Tapered Slot Antenna for Underwater…
1 3
Prof. Dr. Hao Wang was born in Nanjing, China in October 1980. He
received the B.S. and Ph.D. degrees in Electrical and Electronic Engi-
neering from the Nanjing University of Science and Technology
(NJUST), Nanjing, in 2002 and 2009, respectively. Currently, he is an
Associate Professor and Doctoral Supervisor at the School of Elec-
tronic and Optoelectronic Technology, Nanjing University of Science
and Technology. His research interests include anti-jamming technol-
ogy for Chinese navigation, satellite communication system, phased
and digital beam forming radar technology, gap waveguide technology,
millimeter wave antennas, and ultra-wideband antennas, etc. In 2011,
his doctoral thesis “Research on Microstrip Antenna” was nominated
for “National Excellent 100 Doctoral thesis”. In recent years, more than
30 research papers have been published in IEEE Trans. Antenna and
Propagation and IEE Trans. Microwave Technology and more than 60
research papers have been published in the international conferences.
Badar Muneer was born in Mirpurkhas Pakistan in 1987. He received
the B.S degree in communication systems engineering from Institute
of Space Technology, Islamabad, Pakistan, in 2008 and the M.Eng.
degree in Telecommunication Engineering from NED University of
Engineering and Technology, Karachi, Pakistan, in 2012. He has a
Ph.D. degree in Electromagnetism Field and Microwave Technology
from University of Science and Technology of China (USTC), Hefei,
P.R. China. He is currently working as Associate Professor at Depart-
ment of Telecommunication Engineering, Mehran UET Jamshoro,
Pakistan. From 2016 to 2018, he has been associated with Chinese
Academy of Science under President’s International Fellowship Initia-
tive (PIFI) as postdoctoral fellow. From 2008 to 2011, he was with a
satellite broadcasting company as a satellite engineer. He worked on
VSAT, CATV and many modern broadcast equipment. His current
research interests are in the area of microwave and millimeter-wave
technology, SIW based power dividers and phase shifters and anten-
nas, liquid metal antennas.
Zaheer Ahmed Dayo was born Sindh Pakistan in 1989. He received the
B.E degree in telecommunication engineering and M.E degree in tele-
communication engineering management from Mehran University of
Engineering Technology (MUET) Jamshoro Sindh Pakistan in the
year 2011 and 2014 respectively. He is currently pursuing the PhD
degree under the supervision of Professor Qunsheng Cao, with major in
Communication Information System, at college of Electronic Infor-
mation Engineering, Nanjing University of Aeronautics Astronautics
(NUAA), Nanjing city, Jiangsu province P.R China. His current
research interests include compact, wideband and high gain antennas,
designing of antenna array topology and optimization techniques,
multiband and slot antennas, reconfigurable and metamaterial inspired
antennas.

19. P. Soothar et al.
1 3
Prof. Dr. Bhawani Shankar Chowdhry is the Meritorious Professor, Fac-
ulty of Electrical, Electronics, Telecommunication and Computer Engi-
neering at Mehran University of Engineering Technology, Jamshoro
(MUET), Pakistan. He did his B. Eng. in 1983 from MUET and PhD in
1990 from School of ECS, University of Southampton, UK. He has
more than 30 years of teaching, research and administrative experience
in the field of Information and Communication Technology. He has the
honor of becoming one of the editor of books “Wireless Networks,
Information Processing and Systems”, CCIS 20, and “Emerging Trends
and Applications in Information Communication Technologies, CCIS
281, and Wireless Sensor Networks for Developing Countries”, CCIS
366, published by Springer Verlag, Germany. His list of research publi-
cation crosses to over 60 in national and international journals, IEEE
and ACM proceedings. Also, he has Chaired Technical Sessions in
USA, UK, China, UAE, Italy, Sweden, Finland, Switzerland, Pakistan,
Ireland, Denmark, and Belgium. He is member of various professional
bodies including chairman: chairman IEEE communication society
(COMSOC), Karachi Chapter, Region10 Asia/Pacific, Fellow IEP, Fellow IEEEP, Senior Member, IEEE
Inc. (USA), Senior Member ACM Inc. (USA).
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