Page 185 - 2023-Vol19-Issue2

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edges were also carved to achieve the resonance frequencies
and increase the return loss value. The single feed antenna
exhibited return losses of 30 dB and 42 dB at 28/38 GHz,
respectively. The single-element design could operate at fre-
quencies ranging from 27.6 to 28.3 GHz in the 28 GHz band
and from 35.2 to 47.2 GHz in the 38 GHz band.
In [18], a single-band antenna operating at 60 GHz was
proposed. The antenna features a Q slot engraved on the radi-
ating patch and is built on a 1.6 mm thick FR-4 substrate with
a permittivity of 4.3. The overall dimensions of the antenna
are 12.9 × 14 × 1.6 mm3, and it has a partial ground plane
length of 2.2 mm. The antenna exhibits a resonance frequency
of 60.06 GHz, an impedance bandwidth of 12.11 GHz, a re-
turn loss of 24 dB, a gain of 8.62, and a radiation efficiency
of 82.15%. Despite its robust radiation characteristics, this
antenna is a large single-band antenna.
In [29], a dual-band rectangular patch antenna was devel-
oped with two symmetric back-to-back L-shaped slots and a
single square slot in the center. The antenna is constructed
on a Rogers RT5880 substrate measuring 20 × 16.5 × 0.508
mm3, with a dielectric permittivity of 2.2 and a loss tangent of width, and gain, achieved by developing a small but high-
0.0009. This antenna resonates at 25.98 GHz and 28.2 GHz,
with return losses of 24.14 dB and 25.45 dB, and impedance
bandwidths of 0.55 GHz and 1.1 GHz. The antenna achieves
gains of 8.63 dBi and 11.26 dBi in both bands, respectively,
with a wide impedance bandwidth and high gain in the second
band. However, the first band has limited bandwidth, and the
antenna itself has a large physical size.
The article [30] describes a dual-band, wideband com-
posite patch antenna that utilizes a modified circular primary
patch and a secondary parasitic patch element. This antenna
was designed to operate in the 28/38 GHz bands and was
printed on a Rogers Ro 3003 TM substrate with a dielectric
constant of 3 and dimensions of 7.5 × 8.8 × 0.25 mm3. The
antenna has impedance-matching bandwidths of 1.23 GHz at
28 GHz and approximately 1.06 GHz at 38 GHz. The reflec-
tion coefficient for the 28 GHz band has a minimum value of
-34.5 dB, while the minimum value for the 38 GHz band is
-27.3 dB. The radiation pattern has a peak gain of 6.6 dBi at
28 GHz and 5.86 dBi at 38 GHz.
In [31], a dual-band microstrip patch antenna with dimen-
sions of 15 × 10 mm2 was proposed for use in the 28/38 GHz
frequency bands. The antenna utilized Rogers 5880 as its
substrate material, with a thickness of 0.508 mm, a loss tan-
gent of 0.0009, and a dielectric constant of 2.2. The antenna’s
gain was measured to be 7.1 dB at 28 GHz and 7.9 dB at 38
GHz, with impedance bandwidths of 1 GHz (27.6 GHz - 28.6
GHz) and 1.2 GHz (37.4 GHz - 38.6 GHz) in the respective
frequency bands.
The authors of the publication [32] presented a rectangular
antenna for the 60 GHz frequency band. The antenna has
Gaid & Ali
dimensions of 4.84 x 3.18 x 0.308 mm3 and was fed using
a quarter-wave transformer line. Resonance was achieved
by loading the patch with two identical E-shaped slits. The
antenna was positioned on a Rogers RT 5880 substrate with
a relative permittivity of 2.2, a tangent loss (tand ) of 0.0009,
and a thickness of 0.308 mm. The design offers an impedance
bandwidth of 2.97 GHz (ranging from 58.67 GHz to 61.64
GHz); with a maximum return loss of 39.27 dB and a VSWR
of 1.022. The design also achieved a maximum radiation
efficiency of 91.7%, a maximum gain of 8.63 dBi (at 58 GHz),
and a gain of 8.40 dBi at the resonance frequency.
The preceding discussion highlights that some proposed
antenna designs suffer from poor gain, non-multiband func-
tionality, or large dimensions. Although certain designs have
a high gain and wide bandwidth, they are too massive for
smartphone integration. Additionally, the planned 5G bands
of 28 GHz, 38 GHz, and 60 GHz exhibit considerable path
loss, necessitating tiny yet high-gain antennas that can cover
the required frequency bands.
This study aims to balance antenna size, impedance band-
gain antenna with multi-band functionality and sufficient
impedance bandwidth. The High-Frequency Structural Sim-
ulator (HFSS), which employs the Finite Element Method
(FEM), is utilized for design, simulation, and optimization.
The accuracy of the simulation results is verified using Com-
puter Studio Technology (CST), which utilizes the Finite Inte-
gration Technique (FIT).
The remainder of the paper is structured as follows: Sec-
tion II describes the proposed antenna design while Section
III examines the impact of various antenna parameters on S11
performance. Section IV presents the simulation results for
the optimized antenna’s characteristics, and Section V summa-
rizes the article’s conclusions and outlines future directions.
II. THE TRI-BAND ANTENNA DESIGN
In this work, we aim to design a rectangular antenna that is
suitable for 5G smartphones and can operate in the approved
frequency bands of 28 GHz, 38 GHz, and 60 GHz. Our goal
is to achieve optimal multi-band functionality, high gain, and
high radiation efficiency while minimizing the antenna’s size.
We will describe the design process leading to the final design
in this section, utilizing HFSS software for design, simulation,
and antenna optimization.
A. The Design Steps
Developing a millimeter-frequency microstrip antenna re-
quires considering three critical aspects. Firstly, determining
the resonant frequencies of the antenna is crucial. Secondly,
selecting the dielectric substrate material used to build the