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Therefore, the mm-wave spectrum, with higher data rates,
wider bandwidths, and faster response times, is seen as the
appropriate answer to these growing challenges. The mm-
wave spectrum has a frequency range of 30 GHz to 300 GHz.
Utilizing mm-wave frequencies in 5G networks has several
advantages, including the availability of bands at 28 GHz,
38 GHz, and the unlicensed band at 60 GHz. Due to signifi-
cant loss in free space path loss, penetration, and absorption
losses in mm-wave communications, the same frequency can
be reused repeatedly in a limited region with acceptable band-
width efficiency. Furthermore, mm-wave communication is
naturally safe and private due to its limited transmission range with impedance bandwidths of 231 MHz and 92 MHz, re-
and narrow bandwidth. Sophisticated antenna arrays can also
be developed and incorporated into printed circuit boards due
to the small physical size of mm-wave antennas [13] [14] [15].
Antennas are essential components of wireless communi-
cation systems, and they must be designed to fit within the
confines of small mobile devices. 5G antennas must also have
a wide bandwidth and operate in multiple frequency bands.
Additionally, mm-wave antennas must be energy-efficient,
have high gain and directivity, and mitigate the effects of sig- 0.787 mm3 Rogers RT-5880 dielectric substrate with er = 2.2
nal path loss and power requirements. To meet these demands,
the Microstrip Patch Antenna (MSPA) technology is the best
solution for 5G wireless networks [16] [17].
MSPAs are tiny, lightweight, inexpensive to produce, and
easy to fabricate. They are also physically strong and can
be mounted on virtually any surface, making them a suit-
able candidate for use in compact wireless devices and high-
directional antenna arrays for base stations. However, MSPAs
have some limitations due to substrate losses, copper losses,
and surface waves, such as limited bandwidth, poor gain, and
low efficiency [18] [19]. Therefore, several approaches are
available to enhance MSPA performance, including feeding
techniques, defective ground structure (DGS), etching slots
and slits in the ground and on radiating elements, inserting
metamaterial into the antenna’s patch and ground plane, mod-
ifying the form of the patch, partial ground approaches, and
multi-layer insulating substrates [20] [21] [22].
Several studies have been conducted on single, dual, or
multi-band mm-wave frequencies, as documented in [23] [24]
[25] [26] [27] [28] [29] [30] [31] [32]. The study presented
in [23] introduced a small dual-band dolly-shaped antenna
(DBDSA) that resonates at 23.52 GHz and 28.39 GHz. The
antenna utilized a 7 × 7 × 1.28 mm3 Rogers RO3010 substrate
with a dielectric constant of 10.2 and a loss tangent of approx- were poor.
imately 0.0022. The DBDSA achieved an overall radiation
efficiency of 80%, with a consistent gain of 5.51 dBi in the
first band and a gain of 4.55 dBi in the second band. The
lower band impedance bandwidth was 1.16 GHz (23.16 GHz
- 24.32 GHz), while the upper band impedance bandwidth
was 634 MHz (28.078 GHz - 28.712 GHz). However, the
Gaid & Ali
design has a complex geometrical structure, modest gain, and
bandwidth.
Similarly, for future 5G communication systems, the work
reported in [24] proposed a substrate-integrated waveguide
(SIW) slot antenna. The antenna used a Rogers RT-duroid
5880 substrate with a height of 0.254 mm, a dielectric con-
stant of 2.2, and a loss tangent of 0.003, with dimensions of
7.5 × 27.06 × 0.254 mm3. The suggested geometry consisted
of a central circular ring and horizontal and vertical vias. The
designed antenna resonated at 28.13 GHz and 37.97 GHz,
spectively. The peak gains achieved in the lower and higher
bands were 7.27 dBi and 8.46 dBi, respectively, with radia-
tion efficiency of 88.25% and 86.30% in the lower and upper
bands, respectively. However, this antenna had a large size
and narrow bandwidth.
In [25], a compact, single-band, bow-tie-shaped microstrip
patch antenna for wideband applications was described. The
modified bow-tie structure was designed on top of an 8 × 8 ×
and tand = 0.0009, supported by a full 0.017 mm thick copper
ground. Diagonal slots inside the geometry were provided
for exact resonance. The antenna had a return loss of 25.45
dB, a simulated impedance bandwidth of 1.88 GHz (26.81-
28.69 GHz), a gain of 7.0 dBi, and a radiation efficiency of
74% at the resonance frequency of 27.77 GHz. Although this
antenna had a small size, acceptable bandwidth, and good
gain, its radiation efficiency was low, and it lacked multiband
capabilities.
Masood Ur-Rehman et al. [26] proposed a tri-band slotted
patch antenna operating at mm-wave frequencies of 28 GHz,
38 GHz, and 61 GHz. The suggested antenna had an overall
dimension of 5.1 × 5 × 0.254 mm3 and was supplied by a
microstrip line. The antenna was built on a single layer of
Rogers RT/ Duroid 5880 printed circuit board with a thickness
of 0.254 mm, a tangent loss of 0.0009, and a relative permit-
tivity of 2.2. Three L- and F-shaped slots were put into the
radiating patch. The antenna achieved peak gains of 7.2, 7.22,
and 6.5 dBi in the three bands, with radiation efficiencies of
86%, 91%, and 85%, respectively. The -10 dB impedance
bandwidths obtained at return losses of roughly 12, 22, and
12 dB were 0.84, 0.37, and 0.9 GHz, respectively. Despite its
tiny size, adequate radiation efficiency, and reasonable gains,
the return losses and realized bandwidths at the three bands
Fadwa Alnemr et al. [27] developed a dual-band circu-
larly polarized antenna that operates at 28/38 GHz operating
frequencies. The antenna was printed on a Rogers RT 5880
substrate with dimensions of 20.4 × 26.4 mm2 and a thickness
of 0.508 mm, with a circular hole in the patch’s center and
four slits in the corners. Microscopic holes on the patch’s