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13.1 Introduction
Nowadays technology in wireless communication started to grow rapidly. This evolution is increasing due to new generation of data network, i.e. 5G that has been newly
introduced [1]. Starting from analog (1G) to digital (2G), then continuing with the
(3G) that provided high data rate and (4G) with cellular wireless communication
systems that were mostly launched in every country [2]. Besides, there are some
problems that had been faces in 4G technology such as high energy consumption,
limited bandwidth, and spectrum crisis. To solve these problems, the millimeterwave band around 20–300 GHz was used to offer a large bandwidth, high gain,
and minimum size to support in data transmission in wireless communication. The
millimeter-wave band was considered as a potential carrier frequency that is important to be one of the 5G technologies [4]. One of the antennas that were developed to
enable operate in 5G applications, especially for bringing more transmission capacity
and bandwidth is dielectric resonator antenna (DRA) [3].
The dielectric resonator antenna gives various advantages such as reduced radiation efficiency and low bandwidth impedance because of lossy silicon substrate
materials. This antenna usually has a physical properties such as small size, low
weight, and low cost [3]. These properties gave many advantages when designing
an antenna as they can easily develop the use of the antenna in various applications.
The dielectric resonator antenna covers a greater bandwidth as well as lower losses
compared to microstrip patch antenna which makes it very suitable for applications
at and over the millimeter-wave frequency [5].
The miniaturized antennas come from different shapes such as rectangular, hemispherical, cylindrical, and hybrid antennas. The two most common shapes of dielectric resonators antenna used are cylindrical and rectangular. But the advantage of
using the rectangular shape is that it has three independence geometrical dimensions
(i.e., length, width, and height). Rectangular structures are proposed to provide more
versatility since two of the three dimensions can be changed freely for given resonant
frequencies and associated by low degree of significance of differences compared to
other shapes [3]. Basically, the shape of this antenna is essentially defined by a few
parameters such as height, width, and depth of DRA and dielectric constant.
Higher-order mode essentially supports for high frequency and high gain [8]. The
higher-order mode is one of the methods that is used to increase or optimize the value
of gain for the DRA. Other than that, there were some other method that are used to
increase the gain of the DRA such as stacking DRAs on top of each other, creating
a shallow pyramidal horn, positioning a circularly polarized DRA within a circular
cavity and the deployed dielectric superstrates as additional structures. The higherorder mode excitation is the simplest method of gain enhancement as compared to
other techniques [9].
Thus, this research is aimed at proposing a better DRA design in rectangular
shaped form for 5G application. According to [2], the frequency of 28 GHz achieved
a wide impedance bandwidth and good return loss covering the targeted 5G bands.
In this research, the antenna is proposed at an operating frequency of 28 GHz and
S. B. Ismail et al.
13.1 Introduction
Nowadays technology in wireless communication started to grow rapidly. This evolution is increasing due to new generation of data network, i.e. 5G that has been newly
introduced [1]. Starting from analog (1G) to digital (2G), then continuing with the
(3G) that provided high data rate and (4G) with cellular wireless communication
systems that were mostly launched in every country [2]. Besides, there are some
problems that had been faces in 4G technology such as high energy consumption,
limited bandwidth, and spectrum crisis. To solve these problems, the millimeterwave band around 20–300 GHz was used to offer a large bandwidth, high gain,
and minimum size to support in data transmission in wireless communication. The
millimeter-wave band was considered as a potential carrier frequency that is important to be one of the 5G technologies [4]. One of the antennas that were developed to
enable operate in 5G applications, especially for bringing more transmission capacity
and bandwidth is dielectric resonator antenna (DRA) [3].
The dielectric resonator antenna gives various advantages such as reduced radiation efficiency and low bandwidth impedance because of lossy silicon substrate
materials. This antenna usually has a physical properties such as small size, low
weight, and low cost [3]. These properties gave many advantages when designing
an antenna as they can easily develop the use of the antenna in various applications.
The dielectric resonator antenna covers a greater bandwidth as well as lower losses
compared to microstrip patch antenna which makes it very suitable for applications
at and over the millimeter-wave frequency [5].
The miniaturized antennas come from different shapes such as rectangular, hemispherical, cylindrical, and hybrid antennas. The two most common shapes of dielectric resonators antenna used are cylindrical and rectangular. But the advantage of
using the rectangular shape is that it has three independence geometrical dimensions
(i.e., length, width, and height). Rectangular structures are proposed to provide more
versatility since two of the three dimensions can be changed freely for given resonant
frequencies and associated by low degree of significance of differences compared to
other shapes [3]. Basically, the shape of this antenna is essentially defined by a few
parameters such as height, width, and depth of DRA and dielectric constant.
Higher-order mode essentially supports for high frequency and high gain [8]. The
higher-order mode is one of the methods that is used to increase or optimize the value
of gain for the DRA. Other than that, there were some other method that are used to
increase the gain of the DRA such as stacking DRAs on top of each other, creating
a shallow pyramidal horn, positioning a circularly polarized DRA within a circular
cavity and the deployed dielectric superstrates as additional structures. The higherorder mode excitation is the simplest method of gain enhancement as compared to
other techniques [9].
Thus, this research is aimed at proposing a better DRA design in rectangular
shaped form for 5G application. According to [2], the frequency of 28 GHz achieved
a wide impedance bandwidth and good return loss covering the targeted 5G bands.
In this research, the antenna is proposed at an operating frequency of 28 GHz and