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1. XXX-X-XXXX-XXXX-X/XX/$XX.00 ©20XX IEEE
Design of wideband dielectric resonator antenna with
square slots excited using microstrip line at 26 GHz.
Irfan Ali
Wireless Communication Centre,
Universiti Teknologi Malaysia,
Johor Bahru 81310, Malaysia
irfan_lrk_15@yahoo.com
Hafizal Mohamad
Wireless Network and Protocol
Research Lab, MIMOS Berhad, Kuala
Lumpur,Malaysia
hafizal.mohamad@mimos.my
Mohd Haizal Jamaluddin
Wireless Communication Centre,
Universiti Teknologi Malaysia,
Johor Bahru 81310, Malaysia
Haizal@fke.utm.my
Abinash Gaya
Wireless Communication Centre,
Universiti Teknologi Malaysia,
Johor Bahru 81310, Malaysia
abinashgaya@gmail.com
Abstract—A design of wideband dielectric resonator antenna
at 26 GHz for 5G communication applications is proposed in
this paper. Square shaped slots of two different sizes are
introduced in the DRA to reduce the quality factor (Q-factor);
thus, to achieve wide bandwidth. The microstrip feed line is used
to excite the DRA. The proposed antenna structure has achieved
a bandwidth of 3 GHz (11.5 %) from 25 GHz to 28 GHz and a
peak gain of 4.8 dBi with a radiation efficiency of 93%.
Keywords—Dielectric resonator antenna, Square shaped slots,
Wide bandwidth, Microstrip line
I. INTRODUCTION
Dielectric resonator antenna has received tremendous
attention due to its superior features of low losses, lightweight,
low profile, wideband, and ease of excitation [1]–[5]. Another
advantage of DRA offers high radiation efficiency because of
the absence of surface wave and metallic losses. These
attractive features make the DRA as an alternative to
conventional and metallic antennas such as microstrip patch
antennas especially at millimetre wave frequencies [6], [7]. As
a result, DRA is being proposed as the best candidate for
future fifth generation (5G) wireless communication
applications. Furthermore, Dielectric resonator antennas can
be designed with different shapes (rectangular, cylindrical,
hemispherical and triangular) [8]–[12] and excited by using
various feeding methods like microstrip feed line [13], probe
feed [14], an aperture coupled [15], and a co-planar waveguide
(CPW) [16].
Over the last three decades, many research efforts have
been paid on the bandwidth enhancement of DRA, such as
stacking multiple DRAs [17], [18], modification of the shape
of DRA [19], [20], perforations [21]. These methods have
major drawbacks of structural complexity and make antenna
bulky which limits the applications for modern
communication which require small size antennas. In this
paper, compact size and wideband DRA using square slots
excited by using the simple microstrip feed line is presented.
The main objective of this research work is to design a smaller
size and wide bandwidth DRA at 26 GHz frequency to be
applied for the future 5G communication applications.
II. GEOMETRY AND STRUCTURE
The configuration of the reference and proposed DR
antennas excited using microstrip line feed are shown in
Fig.1(a),(b) and (c), respectively. The reference DR antenna 1
is simple square shaped having dimensions of length, width
and height, while in the reference DR antenna 2, a square
shaped slot with length × width ( × = 0.86 ×
0.86 ) is drilled at the centre of the DRA to enhance the
bandwidth of the antenna by reducing Q-factor. Further to
reduce the Q-factor and to increase the bandwidth, four slots
with length r ×width s ( × = 0.17 × 0.17 ) are
drilled at the corner of the proposed DR antenna. Since, the Q-
factor is inversely proportional to the bandwidth, thus, results
improvement in bandwidth.The DRAs are mounted on the
11 × 12 ground plane having dimensions of the
length ,width , and height
ℎ . The Rogers RT/Duroid 5880 substrate with a relative
permittivity of 2.2 and thickness ℎ Of 0.254 mm is
selected. The microstrip feed line is etched on the top of the
substrate whereas the ground plane (GP) is on the opposite
side. All simulations are performed using CST Microwave
studio. The resonant frequency of the DRA is determined as
[22]:
=
2 √
+ +
Where c is the speed of light, is the resonant frequency
in (GHz). The optimized dimensions of the antenna design are
given in Table 1.
(a) Ref. DR Antenna 1 (b) Ref. DR Antenna 2
2019 IEEE Asia-Pacific Conference on Applied Electromagnetics (APACE) 25 - 27 November 2019 at Malacca,
Malaysia

2. (c) Prop. DR Antenna
Fig. 1. The geometry of the reference and proposed DR antennas fed by a
microstrip transmission line.
TABLE I. OPTIMIZED DIMENSIONS OF THE DESIGNED DR
ANTENNAS.
Parameter Dimension (mm) Description
4.3
4.3
2.7
Length of DRA
Width of DRA
Height of DRA
11 Length of substrate
12 Width of substrate
0.254 Height of substrate
11 Length of ground
12 Width of ground
0.0157 Height of ground
( ) 0.86 Length of square slot
( ) 0.86 Width of square slot
( ) 0.17 Length of square slot
( ) 0.17 Width of square slot
III. RESULTS AND DISCUSSIONS
The reference and proposed DR antennas are simulated
using the CST Microwave studio. The DR antennas are
designed and investigated at millimetre wave frequency of 26
GHz for the fifth generation (5G) applications. Fig. 2. shows
the S11 of the proposed antenna and reference antennas. It can
be seen from the figure; the proposed antenna resonates at 26
GHz frequency and offers a bandwidth of 3 GHz (11.5 %),
from 25 GHz to 28 GHz. The proposed antenna obtained
wider bandwidth compared to reference antennas.
Fig. 2. Simulated S11 of the proposed and reference antennas.
Fig. 3. Simulated gain versus frequency of the reference and proposed
antennas.
Fig. 4. Simulated radiation efficiency versus frequency.
Fig. 5. Normalized radiation patterns in the E-plane (xz-plane) at 26 GHz.
-40
-30
-20
-10
0
24 25 26 27 28
S
11
[dB]
Frequency [GHz]
Ref. Ant.1
Ref.Ant.2
Prop. Ant.
0
1
2
3
4
5
6
7
24 25 26 27 28
Gain
[dBi]
Frequency [GHz]
Ref.Ant.1
Ref.Ant.2
prop.Ant.
0.8
0.84
0.88
0.92
0.96
1
24 25 26 27 28
Rad.Efficiency
[x100]
Frequency [GHz]
Ref.Ant.1
Ref.Ant.2
prop. Ant.
-50
-40
-30
-20
-10
0
10
-180 -120 -60 0 60 120 180
Normalized
Gain
[dB]
Theta [Degree]
Ref.Ant.1
Ref.Ant.2
Prop.Ant.
-15
-10
-5
0
5
-180 -120 -60 0 60 120 180
Normalized
Gain
[dB]
Theta [Degree]
Ref.Ant.1
Ref.Ant.2
Prop.Ant.
-10 dB BWBW
2019 IEEE Asia-Pacific Conference on Applied Electromagnetics (APACE) 25 - 27 November 2019 at Malacca,
Malaysia

3. Fi.g. 6. Normalized radiation pattern in the H-plane (yz-plane) at 26 GHz.
Fig. 3. represents the gain versus frequency plots of the
proposed and reference DR antennas. A gain of 4.7 dBi, 4.8
dBi has achieved for the reference DR antennas and proposed
DR antenna, respectively. Fig. 4. Shows the simulated
radiation efficiencies of the reference and proposed antennas.
The proposed antenna has achieved an efficiency of 93% and
the reference antenna 1 94% and reference antenna 2 93 %,
respectively. While the simulated normalized radiation pattern
in the E-plane (xz-plane) and H-plane (yz-plane) at 26 GHz
for the reference antennas and proposed antenna are shown in
Fig. 5 and Fig. 6., respectively.
TABLE 2: SIMULATED PERFORMANCE COMPARISON OF THE REFERENCE DR ANTENNAS WITH THE PROPOSED DR ANTENNA.
Parameters Freq. Range of VSWR≤ % Bandwidth of VSWR≤ Gain (dBi) Rad. Eff. (%)
Ref. DR Ant.1 24.9-27.4 GHz 9.6 4.7 94
Ref. DR Ant.2 24.9-27.7 GHz 10.7 4.8 93
Prop. DR Ant. 25-28 GHz 11.5 4.8 93
* Rad.Eff.-Radiation efficiency in %.
Table 2. summarizes the results and shows the comparison
between the reference and proposed antennas in terms of
bandwidth, gain and radiation efficiency. From the table, it is
clear that the proposed DR antenna has a wide bandwidth
compared to the reference DR antenna 1 and reference DR
antenna 2.
IV. CONCLUSION
A wideband dielectric resonator antenna excited using
microstrip feed line is presented. The proposed DR antenna
structure achieved a wide bandwidth of 11.5%, from 25-28
GHz with a radiation efficiency of 93%. In addition, the gain
obtained is 4.8 dB. This antenna is compact, simple in
structure, good performance and is suitable for the 5G
applications.
ACKNOWLEDGEMENT
The authors would like to thank the Ministry of Higher
Education (MOHE) under FRGS (vote 4F283 and 4F733) and
under Research University Grant (votes 19H56 and 03G59)
and Science fund Grant (Vot.No.4S134) and Higher Centre of
excellence Grant (vote 4J220) for supporting this research
work.
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2019 IEEE Asia-Pacific Conference on Applied Electromagnetics (APACE) 25 - 27 November 2019 at Malacca,
Malaysia