1. Introduction
Satellite and radar applications work in different frequency bands, e.g., the X-band,
Ka-band, Ku-band, and K-band. Multiband or ultra-wideband antennas operate simultaneously
on different frequency bands. Generally, different antennas need to be used for the
various frequency bands. In that case, the use of multiple antennas to cover multiple
applications increases the cost and complexity of the communication systems [1-3]. The beamforming array antenna is able to handle multiple data streams and can form
multiple directed beams at the same time. However, such antennas are inherently bulky
and rely on mechanical steering. Optimum weight, size, and cost could support several
upcoming satellite applications spread throughout the C and Ku-bands, including fixed-satellite
services (3.7 GHz to 4.2 GHz and 11.5 GHz to 11.7 GHz), and some frequency bands (12
GHz to 18 GHz and 18 GHz to 27 GHz) are used in both satellite and radar systems [4-9]. It is known that 5G networks offer several advantages compared to the current networking
systems by providing higher data rates and increased bandwidth. The mmWave frequency
bands have become a good option to overcome the inadequacies in cellular mobile communications.
The bandwidth available for mmWave communications is shown in Fig. 1. Wedged between microwave and infrared waves, this spectrum can be used for high-speed
wireless communications, as seen with the latest 802.11ad Wi-Fi standard (operating
at 60 GHz). Current density helps by providing the desired 5G data rate [10-13].
Another advantage of short waves is that they exchange data quickly, even if the response
time is short. Today, the mmWave bandwidth is used for various applications, such
as high-quality video streaming, radio astronomy, and military applications. Generally,
the above systems are too weak for broadband usage due to high bandwidth and internal
impacts, as well as repeated rainwater absorption [14-17]. As a result, the recent 5G networking systems are the best choice for overcoming
rainwater absorption, lower data speeds, low quality of services (QoS), and so on.
This development in mmWave technology is just part of future 5G networks.
The Sub-6 GHz band is an important part of a communication system model operating
in a lower 5G band. It can be able to deliver information with a high data throughput
and other user benefits [19-21].
Fig. 1. Available bandwidth in mmWave communications[18].
The term mmWave indicates a specific portion of the radio frequency spectrum between
24 GHz and 100 GHz (more specifically, mmWave systems have frequency ranges between
30 and 300 GHz, where a total of around 250 GHz bandwidths are available), which has
a very short wavelength. This part of the spectrum is pretty much unused, so mmWave
technology aims to greatly expand the amount of bandwidth available. Lower frequencies
are more heavily congested with TV and radio signals as well as the current 4G LTE
networks, which typically sit between 800 and 3,000 MHz. Another advantage of mmWave
is that it can transmit data at faster rates, although it has only a short transmission
distance [22-27].
In this paper, we present a slotted crescent-shaped patch antenna to operate at different
frequency bands that are frequently used in satellite communications and radar systems,
and that will be used for future mmWave 5G mobile applications. The proposed antenna
exhibits very good impedance matching over the frequency bands of 17.73 GHz to 26.04
GHz, 29.60 GHz to 31.02 GHz, and 35.40 GHz to 38.65 GHz along with a minimum return
loss of -33.076 dB at the operating frequency of 37 GHz. The characteristics of the
proposed antenna, such as return loss, antenna gain, and radiation patterns are investigated
in this paper. All the simulation results were obtained by the computer simulation
technology microwave studio (CST-MWS). CST-MWS is professionally recognized and widely
used software for estimating all the radiation properties of an antenna system. It
has a rich set of solvers and tools to design, analyze, and optimize any electromagnetic
system. The key features of the proposed crescent-shaped patch antenna can be summarized
as follows.
· The proposed antenna is compact and capable of working at multiband frequencies.
· The gain of the antenna is relatively good.
· The bandwidth of the proposed antenna is larger than the conventional patch antenna
at the respective resonating frequencies.
· Since the antenna is designed for 5G networks, it will support higher data rates.
· Overall, the proposed antenna can be used for satellite, radar, and mmWave communication
applications.
The rest of the paper is structured as follows. The next section describes related
work. Section 3 describes the proposed crescent-shaped patch antenna model. Section
4 deals with the performance evaluation of the proposed antenna, based on simulation
results. Finally, the conclusion of our manuscript is drawn in Section 5.
2. Related Work
A lot of research has been done prior to the design of the proposed antenna. A multiband
patch antenna sized 18${\times}$16 mm$^{2}$ was presented in [1]. That antenna resonates at 7.62 GHz, 9.20 GHz, 11.07 GHz, and 15.02 GHz. The size
is much larger than our proposed antenna. A miniature modified patch antenna for K-band
applications with the size of 20${\times}$15 mm$^{2}$ was presented in [2], providing a peak gain of 7 dB and bandwidth of 7.9 GHz. A multiband microstrip patch
antenna for K-band, Ku-band, and X-band applications was presented in [3]. The size of that antenna is 17.6${\times}$4.9 mm$^{2}$ and it resonates at 11.5
GHz, 16 GHz, and 21 GHz. An elliptical slot-cut ultra-wideband antenna presented in
[7], its size is 23${\times}$31 mm$^{2}$ with a peak gain of 4 dB and a bandwidth of
13 GHz. In [11], a diamond slot patch antenna with the size of 14.5${\times}$15 mm$^{2}$ was presented,
providing resonating frequencies are 8.67 GHz, 12.52 GHz, 15.23 GHz, and 17.54 GHz.
A circularly polarized printed elliptical wide-slot antenna was presented in [19], sized 17${\times}$18 mm$^{2}$with a peak gain of 7.39 dB. An octagonal shape patch
antenna was proposed in [23]. The size of that antenna is 100${\times}$88 mm$^{2}$ and it resonates at 11.25 GHz,
15.5 GHz, and 17.2 GHz. A compact dual-band slotted elliptical microstrip antenna
for Ku/K band applications was proposed in [25] with a size of 10${\times}$12 mm$^{2}$ and resonating frequencies 14.44 GHz and 21.05
GHz, and gain of 5.59 dB and 5.048 dB, respectively.
3. Design of the Proposed Antenna
Different geometric shapes are used to design microstrip patch antennas to resonate
at the expected frequencies, and among them, the slotted crescent-shaped presented
in this paper is applied to satellite communications, radar systems, and for future
mmWave 5G mobile applications. Fig. 2 shows the front view of the proposed antenna with overall dimensions of 12${\times}$9
mm$^{2}$. The patch is printed on a Flame Retardant 4 (FR-4) dielectric substrate
with a dielectric constant $\varepsilon _{r}$= 4.3, a loss tangent (tan$\delta $)
of 0.02, and substrate thickness $t_{s}$ = 2.40 mm. The antenna consists of two equally
sized slotted crescent-shaped patches, and the distance between them is $a$ = 2.5
mm with line width $t$ = 0.5 mm. The distance between the feed line and the connected
crescent-shaped line is $c$ = 1.75 mm. The diameter of the crescent-shaped patch is
$b$ = 2.60 mm (where $b$ = 0.239${\times}$$\lambda $; $\lambda $ being the wavelength
at the resonant frequency), and the length of the inner slotted circular diameter
is $d$ = 0.8 mm. The thickness of the ground plane ($t_{g}$) and the patch ($t_{p}$)
of the proposed antenna are equal (0.035 mm). Copper is used as the patch conductor
and in the ground plane. A 50 ${\Omega}$ microstrip line with a length $L_{f}$= 3.5
mm is used to feed the antenna. The width of the microstrip line, $W_{f}$, is 1.1~mm,
and it was chosen to provide a line impedance of almost 50 ${\Omega}$. The back view
of the proposed antenna is illustrated in Fig. 3, where the length of the ground ($L_{g}$) is 11 mm, and the width of the ground ($W_{g}$)
is 9 mm. The other parameters of the proposed antenna are listed in Table 1.
Fig. 2. Front view of the proposed antenna.
Fig. 3. Back view of the proposed antenna.
Table 1. Parameter Details.
|
Parameter
|
Value (mm)
|
|
Length of substrate ($L_{s}$)
|
11
|
|
Length of ground plane ($L_{g}$)
|
11
|
|
Thickness of substrate ($t_{s}$)
|
2.4
|
|
Distance between two elements ($a$)
|
2.5
|
|
Length of strip ($c$)
|
1.75
|
|
Width of feed line ($W_{f}$)
|
1.1
|
|
Width of substrate ($W_{s}$)
|
9
|
|
Width of ground plane ($W_{g}$)
|
9
|
|
Thickness of ground plane and patch ($t_{g}$=$t_{p}$)
|
0.035
|
|
Diameter of patch ($b$)
|
2.6
|
|
Diameter of slot ($d$)
|
0.8
|
|
Length of feed line ($L_{f}$)
|
3.5
|
4. Performance Evaluation
The reflection coefficient of the proposed slotted crescent-shaped patch antenna is
depicted in Fig. 4. When a reflection coefficient below -10 dB in this figure is considered, we see
that the antenna resonates at 19 GHz, 25 GHz, 30.26 GHz, and 37 GHz, and among them,
a minimum return loss of approximately –33.076 dB is obtained at 37 GHz. Return losses
of -14.60 dB, -30.56 dB, and -17.25 dB present at 19 GHz, 25 GHz, and 30.26 GHz, respectively.
The VSWR of the antenna is shown in Fig. 5. This figure demonstrates the proper impedance matching in the operating frequency.
A VSWR lower than 2 at the desired frequencies is observed. The minimum VSWR of 1.045
was obtained at 37 GHz.
The 3-D radiation patterns for the gain are illustrated in Fig. 6 at 19 GHz, 25 GHz, 30.26 GHz, and 37 GHz. The maximum gain of 4.68 dB is obtained
at 25 GHz, as depicted in Fig. 6(b), and the minimum gain of 2.89 dB is exhibited at 19 GHz, shown in Fig. 6(a). Moreover, gains at 30.26 GHz and 37 GHz are 4.49 dB and 4.10 dB, as shown in Figs.
6(c) and (d), respectively.
The polar radiation patterns for phi=90$^{\circ}$ at 19 GHz, 25 GHz, and 30 GHz are
presented in Figs. 7(a)-(c). The maximum main lobe magnitude of 4.4 dB exists at 25
GHz, with an angular beamwidth (at 3 dB) of 43.30, whereas the maximum main lobe magnitude
of 2.57 dB is exhibited at 19 GHz, with an angular beamwidth (at 3 dB) of 92.60. The
polar radiation pattern at phi=90$^{\circ}$ is exhibited at 30.26 GHz, as illustrated
in Fig. 7(c), where the main lobe magnitude is 4.53 dB directed at 83$^{\circ}$, and the angular
beamwidth (at 3 dB) is 69$^{\circ}$.
Fig. 4. Reflection coefficient of the proposed slotted crescent-shaped patch antenna.
Fig. 5. VSWR of the proposed slotted crescent-shaped patch antenna.
Fig. 6. (a) Simulated 3-D gain at 19 GHz; (b) Simulated 3-D gain at 25 GHz; (c) Simulated 3-D gain at 30.26 GHz; (d) Simulated 3-D gain at 37 GHz.
Likewise, the polar radiation pattern for phi=90$^{\circ}$ at 37 GHz is illustrated
in Fig. 7(d). Similarly, the 2-D radiation pattern on the xz-plane for phi=0$^{\circ}$ is depicted
in Fig. 7(e). The polar radiation patterns for theta=90$^{\circ}$ at 19 GHz, 25 GHz, 30.26 GHz,
and 37 GHz are shown in Fig. 7(f), where the maximum main lobe direction is 90$^{\circ}$ at 30.26 GHz with an angular
beamwidth of 32.90 and an angular beamwidth of 34.50 with main lobe magnitude of 4.13
dB obtained at 37 GHz.
The surface current distributions across the patch of the proposed antenna at 19 GHz,
25 GHz, 30.26 GHz, and 37 GHz are illustrated in Fig. 8. The strong distribution of surface current is obtained at 25 GHz. About 169 A/m
current flows through the patch of the antenna at this frequency illustrated in Fig. 8(a). At 19 GHz, 30.26 GHz, and 37 GHz approximately 12.9 A/m, 8.5 A/m, and 10.1 A/m currents
flow through the patch of the antenna, whereas the maximum values of the current at
these frequencies are 142 A/m, 93.5 A/m, and 111 A/m, respectively. However, the current
is concentrated through the patch and at the outer edges of the radiating patch, forming
an energy loop and enabling effective radiation.
Fig. 7. (a) Simulated radiation pattern for phi=90$^{\circ}$ on the xz-plane at 19 GHz; (b) Simulated radiation pattern for phi=90$^{\circ}$ on the xz-plane at 25 GHz; (c) Simulated radiation pattern for phi=90$^{\circ}$ on the xz-plane at 30.26 GHz; (d) Simulated radiation pattern for phi=90$^{\circ}$ on the xz-plane at 37 GHz; (e) Simulated radiation pattern for phi=0$^{\circ}$ on the xz-plane at 19 GHz, 25 GHz, 30.26 GHz, and 37 GHz; (f) Simulated radiation pattern for theta=90$^{\circ}$ on the xz-plane at 19 GHz, 25 GHz, 30.26 GHz, and 37 GHz.
Fig. 8. (a) Surface current at 19 GHz; (b) Surface current at 25 GHz; (c) Surface current at 30.26 GHz; (d) Surface current at 37 GHz.
The E-field distributions through the proposed antenna at 19 GHz, 25 GHz, 30.26 GHz,
and 37 GHz are illustrated in Fig. 9. Strong distribution of the E-field is obtained at 25 GHz.
A 44371 V/m E-field presented through the patch of the antenna at this frequency is
illustrated in Fig. 9(b). At 19 GHz, 30.26 GHz, and 37 GHz, maximum E-fields of 42526 V/m, 27573 V/m, and
28649 V/m exist at the patch of the antenna. However, the E-field is concentrated
through the patch and at the outer edges of the radiating patch, forming an energy
loop and enabling effective radiation.
Antenna gain versus the frequency curve is illustrated in Fig. 10. The maximum gain is obtained at 25 GHz where the value is approximately 4.68 dB,
and the minimum gain of 2.89 dB is obtained at 19 GHz. Gain at 30.26 GHz and 37 GHz
is 4.53 dB and 4.10 dB, respectively.
Fig. 9. (a) E-field distributions of the proposed antenna at 19 GHz; (b) E-field distributions of the proposed antenna at 25 GHz; (c) E-field distributions of the proposed antenna at 30.26 GHz; (d) E-field distributions of the proposed antenna at 37 GHz.
Fig. 10. Gain versus frequency curve of the proposed antenna.
Table 2 represents a comparison scenario of recently published relevant works and our proposed
antenna. Overall dimensions (in mm$^{2}$), impedance bandwidth (in GHz), and maximum
gain (in dB) of the reference antennas are compared with the proposed antenna. From
this table, we can see that the proposed antenna’s size is smaller, whereas the impedance
bandwidth and gain are higher than the other antennas. There are, however, some conventional
antennas that have higher gain at a particular frequency, but their bandwidths are
smaller and sizes are larger than our proposed multiband miniaturized crescent-shaped
patch antenna. Undoubtedly, we can say our proposed antenna is robust and more efficient
based on the size, maximum gain, and higher bandwidth. Therefore, this antenna could
be a standard option in practical applications, e.g., satellite communications, radar
systems, and future mmWave 5G applications.
Table 2. Comparative Analysis.
|
Ref.
|
Size (mm$^{2}$)
|
Bandwidth
(GHz)
|
Peak Gain
(dB)
|
|
[2]
|
16${\times}$17
|
7.9
|
7
|
|
[9]
|
7${\times}$10
|
13
|
3.5
|
|
[11]
|
14.5${\times}$15
|
16.66
|
N/A
|
|
[13]
|
20${\times}$20
|
1.07, 0.94
|
3.87
|
|
[16]
|
18${\times}$15
|
6.75
|
3.5
|
|
[17]
|
13${\times}$25
|
10
|
4.8
|
|
[18]
|
17${\times}$18
|
7.78, 2.05
|
7.39
|
|
Proposed
|
11${\times}$9
|
8.4, 1.42, 3.25
|
4.68
|
5. Conclusion
In this paper, a K-band and mmWave frequency band slotted crescent-shaped patch antenna
is proposed. The proposed slotted crescent-shaped patch antenna’s dimension is 11${\times}$9${\times}$2.4
mm$^{3}$, and it can operate in frequency ranges of 17.73 GHz to 26.04 GHz, 29.60
GHz to 31.02 GHz, and 35.40 GHz to 38.65 GHz for satellite communications, radar systems,
and future mmWave 5G applications, respectively. The maximum gain of 4.68 dB was obtained
at 25 GHz, and the minimum efficiency is approximately 73%. Moreover, the proposed
crescent-shaped compact patch antenna is made on a low-cost FR-4 dielectric material
which makes the system more economical.
ACKNOWLEDGMENTS
The authors would like to thank the reviewers for valuable comments, suggestions,
and questions that significantly improved the article.
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Author
Md. Najmul Hossain was born in Rajshahi in the People’s Republic of Bangladesh
in 1984. He is an Associate Professor in the Department of Electrical, Electronic
and Communication Engineering, Pabna University of Science and Technology, Pabna,
Bangladesh. He received his B.Sc. and M.Sc. in Applied Physics and Electronic Engineering
(now called Electrical and Electronic Engineering) from the University of Rajshahi,
Rajshahi, Bangladesh, in 2007 and 2008, respectively. In 2020, he received his Ph.D.
in Advanced Wireless Communication Systems from the Graduate School of Science and
Engineering, Saitama University, Saitama, Japan. He serves as an Editor of the Journal
of Engineering Advancements (JEA). He has served as a reviewer of several SCIE/Scopus
journals and international conferences. His current research interests include antenna
design, advanced wireless communication systems, and corresponding signal processing,
especially for OFDM, OTFS, MIMO, and future-generation wireless communication networks.
Liton Chandra Paul is a Faculty Member in the Department of Electrical, Electronic
and Communi-cation Engineering, Pabna University of Science and Technology, Pabna,
Bangladesh. He completed his B.Sc. in Electronics and Telecommunication Engineering
and his M.Sc. in Electrical & Electronic Engineering at the Rajshahi University of
Engineering & Technology in 2012 and 2015, respectively. He has published several
peer-reviewed journals and international conference articles. He also serves as a
reviewer for several IEEE international conferences and reputed international journals.
His research interests are Antenna and Wave Propagation, AI, Biomedical Engineering,
and Wireless Communication.
Md. Abdur Rahim received his Ph.D. in 2020 in Computer Science and Engineering
from the University of Aizu, Japan. He is an Associate Professor and Chairman of the
Department of Computer Science and Engineering, Pabna University of Science and Technology,
Pabna, Bangladesh. He received his Bachelor of Science (Honours) and Master of Science
in Computer Science and Engineering from the University of Rajshahi, Bangladesh, in
2008 and 2009. His current research interests include human-computer interaction,
pattern recognition, computer vision and image processing, human recognition, and
machine intelligence. He has served as a reviewer for several major SCI/SCIE journals
and as a Technical Program Committee member for many conferences.
Jungpil Shin (Senior Member, IEEE) received a B.Sc. in Computer Science and Statistics
and an M.Sc. in Computer Science from Pusan National University, Korea, in 1990 and
1994, respectively. He received his Ph.D. in computer science and communication engineering
from Kyushu University, Japan, in 1999, under a scholarship from the Japanese government
(MEXT). He was an Associate Professor, a Senior Associate Professor, and a Full Professor
with the School of Computer Science and Engineering, The University of Aizu, Japan,
in 1999, 2004, and 2019, respectively. He has co-authored more than 250 published
papers for widely cited journals and conferences. His research interests include pattern
recognition, image processing, computer vision, machine learning, human-computer interaction,
non-touch interfaces, human gesture recognition, automatic control, Parkinson’s disease
diagnosis, ADHD diagnosis, user authentication, machine intelligence, as well as handwriting
analysis, recognition, and synthesis. He is a member of ACM, IEICE, IPSJ, KISS, and
KIPS. He served as program chair and as a program committee member for numerous international
conferences. He serves as an Editor of IEEE journals and for MDPI Sensors. He serves
as a reviewer for several major IEEE and SCI journals.