Dielectric Resonator Antenna (DRA)

There has been revolutionary growth in the world of wireless communications system. Since its inception wireless technology has undergone many stages of development. Antennas form the most integral part of any wireless communication systems. In order to the keep pace with fast changing requirements of wireless communication market, the fast and efficient antennas are in great demand. Besides it is desired that antennas should be of that type which can be scaled up in frequency. There are two types of antennas which have been able to match up these needs namely micro strip antenna and dielectric resonator antenna. Initially micro strip patch antennas were best suited for it but from last few decades’ dielectric resonator antennas have totally replaced it [1-3]. Since DRAs have an edge over micro strip antennas because of its many attributes namely ease of fabrication, flexibility in feed mechanism, low profile, high radiation efficiency and wide frequency range to name a few. Moreover, DRA is a 3-D structure whereas micro strip antenna is a 2-D structure. In addition, DRA’s are well suited for low-loss applications for the reason that there is no conductor loss in them.

Abstract—A simple compact wideband aperture coupled rectangular dielectric resonator antenna (RDRA) loaded with similar parasitic dielectric elements separated by low dielectric spacers as air gap layers is designed. The bandwidths of the proposed RDRAs are significantly enhanced as compared with the bandwidth of the driven DRA without an air gap. The measurement results are verified experimentally for a one parasitic element case. A bandwidth of 18% and 27% with VSWR better than 2 is achieved for double and triple gaps, respectively. It is interesting to point out that radiation patterns are stable in the entire operation band.

Abstract—Today, worldwide more than five billion of wireless devices are directly communicating for voice and data transmission. The amount of data utilization has increased remarkably and here comes 5G technology with more prominent features, offering high data rate, low latency rate, efficient EM spectrum utilization, an immense machine-2-machine communication, etc. The efficient implementation of 5G technologies requires efficient and compact antennas. This work presents a novel multiband rectangular dielectric resonator antenna for future 5G wireless communication system, having stacked radiator with semi-circular slots etched on the left and right sides of an upper radiator. Additionally, a semi-elliptical slots rectangular microstrip patch antenna of the same dimensions for the purpose of comparison is designed. 28 and 38 GHz, which are the proposed 5G bands by most researchers, are the core target of this work. Alumina with a high relative permittivity of 9.8 is used as a radiator in the design of DRA, while common in the design of both proposed antennas, Rogers RT/DUROID 5880 with a relative permittivity of 2.2 having standard thickness is used as substrate material. Both the proposed antennas have an overall same size of 13 × 11 . 25 mm 2 . The proposed dielectric antenna resonates at 25.4, 34.6 and 38 GHz with 7.34, 4.04, and 3.30 GHz of wide impedance bandwidth covering the targeted 5G, 28, and 38 GHz bands, having a good return loss of − 34 . 7, − 31 . 8, and − 33 . 5 dB, respectively. Further, the proposed dielectric antenna has a maximum radiation efficiency of 97.63%, with overall radiation efficiency greater than 90%, and maximum gain of 7.6 dBi is also noted. On the other hand, the proposed microstrip antenna resonates at 28 and 38 GHz with a 1.49 and 1.01 GHz of moderate impedance bandwidth, having − 23 . 6 and − 27 . 1 dB of satisfactory return loss. Further, the proposed patch antenna has a maximum radiation efficiency of 90.33% at 28 GHz, with overall radiation efficiency of greater than 84%, and moderate gain of 5.45 dBi is also noted. Both the proposed antennas have a nearly omnidirectional radiation pattern at resonance frequencies, with VSWR less than 2. Comparative study of the two proposed antennas regarding radiation efficiency, return loss, gain, data rate, and impedance bandwidth evidently shows that performance of DRA over MPA at millimeter wave is very good. The proposed antennas are simulated in CST Microwave studio v18.

among the applied field and phonons which leads to the damping of the optical lattice vibrations, in turn, causing a dielectric loss. Thus, there is a need for a material to replace the ceramic material. Dielectric resonator antenna with sapphire material overcomes drawbacks of ceramic material and thus outweighs dielectric resonator antenna with ceramic material in terms of better performance. It is a potential prospect for future smartphones and mobile communication. Hence this paper presents a sapphire stacked rectangular dielectric resonator antenna design. The stacked structure gives one of the effective ways of enhancing the impedance bandwidth as well as generating multiple modes of an antenna instead of a single structure design [23–25]. A number of shapes of DRAs are available, but the rectangle-shaped DRA has been put in use as it is the only shape that gives more fabrication flexibility than other geometries, also because this shape achieves better radiation as well as impedance in the design [26]. There are multiple ways or methods to excite an antenna such as microstrip transmission line, coaxial probe feed, coplanar waveguide line, and aperture coupled feed to name a few. Out of all, aperture coupled feed mechanism is mostly employed. The objective behind using aperture coupled feed is that it avoids spurious modes because it keeps feeding networks below the ground plane [27–29]. The five sections of the paper are organized as follows. Section 1 covers the introduction. Section 2 shows antenna design calculation. Section 3 gives antenna configuration and design. Section 4 demonstrates various results and their discussion whereas Section 5 is the conclusion and future scope.

In this paper, beamwidth enhancement method is presented for a DRA. A novel broadbeam copolanar-parasitic rectangular DRA (CoP-RDRA) is proposed which yields broad beam radiation patterns in E- and H-planes simultaneously without utilizing a complex feed mechanism. The novelty of the feed mechanism lies in the fact that a wide feed slot alone excites the two desired modes which are critical to broadside widebeam performance in two planes simultaneously. This is achieved by enhancing the modal resonance bandwidth and merging the two consecutive modes resonances. No additional feed mechanism is required to efficiently couple the two modes, keeping the antenna simple from fabrication view point. However, all the important parameters critical to achieving broad beamwidth in two principal planes simultaneously have been identified, and relations between the wavelength of Mode-I frequency and these parameters have been drawn which give initial values for design dimensions. It is found that parasitic dielectric elements at an optimum gap length from radiating element play an important role in enhancing the beamwidth bandwidth of the antenna and will be shown in the following sections. Here, it is imperative to define the term ‘beamwidth bandwidth’ as a band of frequencies where the antenna yields broad beamwidth of more than 110 ◦ in two planes simultaneously. Single element rectangular dielectric resonator antenna (RDRA) is also designed, and the results are compared with proposed CoP-RDRA in terms of beamwidths in E- and H-planes, beamwidth bandwidth, and radiation pattern stability. The comparisons clearly show that the proposed CoP-RDRA yields wide broadbeam bandwidth with stable radiation patterns and a broadbeam radiation pattern in both principal planes simultaneously.

Before the introduction of the Dielectric Resonator Antenna, it was used for filter applications in microwave circuits. DRA have been proposed as an alternative to the conventional conductor antennas. In high frequency application, as the frequency increases, ohmic losses in conventional antenna increases. DRA has so many advantages features such as compact size, low loss, high efficiency, light weight, ease of excitation, feeding mechanism and versatility in the shape. DRA radiate throughout their entire volume and therefore the amount of energy radiated is larger than the energy stored in their near fields. The basic DRA structure is consist of a DR element of a specific shape. DRA excited by a single feed such as a micro strip line, coplanar waveguide, aperture or coaxial cable. For the simple geometry, permittivity of the DRA decreased to achieve wider bandwidth. The most common method of feeding mechanism is the aperture –coupled arrangement. There are three basic shapes available for common design, including rectangular, cylindrical, and spherical.

Due to the fast growth of technology, the demand for wireless mobile communications has led to the development of antennas that are low profile and small in size. Therefore, in this presentation, a novel broadband, low-profile dielectric resonator antenna using relatively low dielectric constant substrate material has been presented. A broadband low profile dielectric resonator antenna that uses a relatively low dielectric constant substrate has been proposed. A stepped microstrip feeding mechanism has been analyzed to achieve efficient coupling over a wide bandwidth. The DRA has been made from inexpensive widely available substrate material. Furthermore, methods for size reduction of the proposed antenna using metallic patches have been investigated. Simulations as well as experimental results are also presented using Comsol software.

This paper discusses Dielectric resonator antenna which has the potential to replace microstrip antenna specially at high frequency. There are certain advantages that DRA offers such as it has high radiation efficiency, negligible metallic losses, adaptable structure, cheap, low profile and availability of dielectric material having dielectric constant ranging from 1 to 1000.Many present and potential future wireless communication applications require broadband antennas which can work over a wide frequency range. This article first examines the achievable bandwidth by a simple shape dielectric resonator antenna. Then the modern enhanced techniques presented by different authors are discussed.

the micro strip line, perpendicular feed, and lately, the convenient conformal-strip feed have been used. The waveguide fed dielectric resonator antenna was proposed, and reported that waveguide has a much lower feed line loss than other feeding methods .Recently, a dual function DRA filter(DRAF) that combines the DRA and DRF is investigated in 2008 and Slot fed wideband dielectric resonator for wireless application has been proposed in 2010 that enables the DRA for practical use.

Dielectric Resonator Antenna: A dielectric resonator antenna has a dielectric layer and a conducting layer formed on a main surface of the dielectric layer. An electrical contact is formed on the main surface for connecting the dielectric layer to a transmission line for transferring a signal between the dielectric layer and the transmission line. The electrical contact is insulated from the conducting layer. A conducting strip is connected to the electrical contact and is on a side surface of the dielectric layer. The side surface is not on the same plane of the main surface. Rather, the side surface is perpendicular to the main surface of the dielectric layer. A dielectric resonator antenna (DRA) is a radio antenna mostly used at microwave frequencies and higher, that consists of a block of ceramic material of various shapes, the dielectric resonator, mounted on a metal surface, a ground plane. Radio waves are introduced into the inside of the resonator material from the transmitter circuit and bounce back and forth between the resonator

This paper discusses Dielectric resonator antenna which has the potential to replace microstrip antenna specially at high frequency. There are certain advantages that DRA offers such as it has high radiation efficiency, negligible metallic losses, adaptable structure, cheap, low profile and availability of dielectric material having dielectric constant ranging from 1 to 1000.Many present and potential future wireless communication applications require broadband antennas which can work over a wide frequency range. This article first examines the achievable bandwidth by a simple shape dielectric resonator antenna. Then the modern enhanced techniques presented by different authors are discussed.

By removing the shielding and with proper feeding schemes, these DRs are found to be functioning as efficient radiators. In fact, the theoretical investigations on the radiation characteris- tics of DRs were carried out long ago in the 1960s as a sideline and practically suppressed for the prevailing application of oscillators and filters until 1983 [3], [4]. In this year, S. Long et al. published a paper on the cylindrical dielectric resonator antenna (DRA) which studied and examined at length the radiation performances of DRs as antennas [5]. After that, they continued with the research on this subject to explore DRAs in other shapes: rectangle [6] and hemisphere [7]. All their serial work laid the foundation for future extensive investigations on various aspects of DRAs in various forms [8], [9].

Antenna diversity is useful to reduce outages, counter multipath and to improve reliability/quality of the communication link. Three types of diversity schemes can be used such as spatial diversity, polarization diversity and beam pattern diversity. In the case of spatial diversity, multiple antenna elements are spaced apart whereas, in polarization diversity, antennas are oriented orthogonally to each other. In the case of pattern diversity, co-located antennas have radiation patterns, oriented in different directions. Numerous research works can be found in literature regarding pattern diversity achievement using multiple antenna elements; however, achieving pattern diversity using a single radiator is challenging [3, 4]. In the proposed work, pattern diversity has been achieved by using an L-shaped Dielectric resonator antenna (DRA) with modes excited in the single element L-shaped dielectric resonator antenna.

Abstract—A new design of a circularly-polarized (CP) trapezoidal dielectric resonator antenna (DRA) for wideband wireless application is presented. A single-layered feed is used to excite the trapezoidal shaped dielectric resonator to increase resonant frequency and axial ratio. Besides its structure simplicity, ease of fabrication and low-cost, the proposed antenna features good measured impedance bandwidth, 87.3% at 4.21 GHz to 10.72 GHz frequency bands. Moreover, the antenna also produces 3-dB axial ratio bandwidth of about 710 MHz from 5.17 GHz to 5.88 GHz. The overall size of DRA is 21 mm × 35 mm, which is suitable for mobile devices. Parametric study and measurement results are presented and discussed. Very good agreement is demonstrated between simulated and measured results.

Abstract—In this paper, reflectarrays mounted on or embedded in cylindrical and spherical surfaces are designed, analyzed, and simulated at 11.5 GHz for satellite applications. A unit cell consists of a square dielectric resonator antenna (DRA) mounted on or embedded in metallic conformal ground plane is investigated. The radiation characteristics of the designed reflectarrays are investigated and compared with that of planar reflectarray. A 13×13 planar reflectarray antenna on the x-y plane was designed. By varying the length of the DRA element between 2 mm and 6.2 mm a full range from 0 ◦ to 360 ◦

A dielectric resonator antenna (DRA) has become a popular discussion topic among researchers and engineers since it has introduced in the early eighties. DRA has a much wider impedance bandwidth as compared to microstrip antenna because the microstrip antenna radiates only through the narrow radiation slots, whereas the DRA radiates through the whole DRA surface except the ground part [1]. Surface waves avoidance is another attractive feature of the DRA. The dielectric wavelength is smaller than the free space wavelength by a factor of 1/ ε r , both of them can be made smaller in size by increasing ε r [1].

Abstract—A new wideband and high-gain dielectric resonator antenna (DRA) is proposed. Three cylindrical dielectric resonators (DRs) with different materials and different sizes and a metallic cylinder are designed to obtain a wideband bandwidth and a high gain. The stacked structure provides a wideband bandwidth, and the cavity formed by the metallic cylinder provides a high gain. The measured results demonstrate that the proposed DRA has a wide bandwidth from 5.4 to 7.0 GHz with VSWR less than two and a gain around 11 dBi, covering the frequency range of 26%. The experimental and numerical results are discussed and compared with each other, showing a good agreement between them.

The paper presents the effect of relative permeability and relative permittivity on the behavior of a miniaturized antenna. The proposed design is combination of hemi-spherical antenna cavity and a hemi-spherical Dielectric Resonator substance; hence this radiating structure is called as hemi-spherical dielectric resonator antenna (HSDRA). Using the DRA, a volumetric source improves the radiation power factor of the radiating slot.[1] The antenna is designed and simulated on HFSS to effectively observe its far-field and near field radiation pattern and different characteristic parameters of antenna system such as gain, VSWR, return loss. The radiation patterns and fields including different characteristics are studied at 3.75 GHz.

Abstract—A filtering rectangle dielectric resonator antenna (DRA) with high band-edge selectivity is proposed in this paper. The DRA is fed by a simple hybrid feeding structure consisting of a microstrip- coupled slot on the bottom and a thin metallic strip on the side of DRA to excite the fundamental TE y 1 δ 1 mode. The feeding structure establishes a cross-coupled mechanism which includes electric and magnetic coupling. This mechanism introduces two radiation nulls at the band edge without any filtering circuits. By using the designed hybrid feeding structure, a bandpass filtering response is obtained. For enhancing band-edge selectivity, a shorted stub is introduced to weaken the coupling between the two microstrip stubs of the feeding structure. A wide impedance bandwidth of 19% and a flat gain around 5.6 dBi are realized. To validate the proposed design, a prototype is fabricated and measured, showing a favorable agreement with the simulated results.

Abstract—This paper presents the design of a compact rectangular dielectric resonator antenna (RDRA) for wireless applications. A metal plate has been attached to top surface of the RDRA to achieve significant reduction in the resonant frequency of the antenna. A simple microstrip feeding mechanism has been used to excite this compact rectangular DRA. Performance parameters such as resonant frequency, impedance bandwidth, and volume of this compact RDRA are compared with those of the conventional RDRA. Measured characteristics of these RDRAs are in good agreement with the simulated results. The size of the compact RDRA using a low dielectric constant (ε r = 10.3) material resonant at 2.4 GHz is 30 mm × 10 mm × 6.3 mm with a ground plane size of 200 mm × 200 mm.