This paper presents a comprehensive review of the state of art techniques and geometries which have been explored in the areas of Dielectric Resonator Antennas (DRA). With the evolution of first re...

A review of the recent advances in dielectric resonator antennas

This paper presents a hybrid design of Sierpinski Carpet and Minkowski antenna for wireless applications. The hybrid antenna is designed, simulated and fabricated on an FR4 substrate with thickness 1.6 mm and dielectric constant 4.4. The dimensions of antenna are 45 × 38.92 × 1.6 mm3 which operates at various frequencies 3.43 GHz, 4.78 GHz, 6.32 GHz, 8.34 GHz and 9.64 GHz, and can be used for Wi-Max, C-band applications, Point-to-point Hi speed wireless communication and X-band (satellite Communication) applications. The measured results are also compared with the simulated ones which are in agreement with each other. Ansoft High Frequency Structure Simulator (HFSS) is used to design and simulate the antenna.

/pdf/a-novel-hybrid-fractal-antenna-for-wireless-applications-42yqrjw19n.pdf

A Novel Hybrid Fractal Antenna for Wireless Applications

In mathematical definition, a fractal is a self-similar subset of Euclidean space whose fractal dimension strictly exceeds its topological dimension which in turn involves a recursive generating methodology that results in contours with infinitely intricate fine structures. Fractal geometry has been used to model complex natural objects such as clouds coastlines, etc., that has space-filling properties. In the past years, several groups of scientists around the globe tried to implement the structure of fractal geometry for applications in the field of electromagnetism, which led to the development of new innovative antenna configurations called “fractal antennas” which is primarily focused in fractal antenna elements, and fractal antenna arrays. It has been demonstrated that by exploiting the recursive nature of fractals, several marvellous kinds of properties can be observed in antennas and arrays. The primary focus of this article is to provide a compressed overview of the developments in fractal-shaped antennas as well as arrays over the last few decades where the most prominent contributions mostly from IEEE journals have been highlighted. The open intention of this review work is to show an encouraging path to antenna researchers for its advancement using fractal geometries.

https://www.cambridge.org/core/services/aop-cambridge-core/content/view/459AAA3FB59067FCEB92146AD824F3AA/S1759078720000963a.pdf/div-class-title-fractal-antennas-and-arrays-a-review-and-recent-developments-div.pdf

Fractal antennas and arrays: a review and recent developments

In this work, the inverted micro-Stereolithography (SLA) is used to show the potential of such additive manufacturing (AM) technology at prototyping super-shaped dielectric resonator antennas (S-DRAs) rapidly and accurately. The S-DRAs, which exhibit 3D complex geometries, were designed to operate at 3.5 GHz, suitable for the assessment of 5G communications in the mid band. Initially, a cross-starred-shaped S-DRA was designed and manufactured via the inverted micro-SLA by means of a photopolymer resin as material. As no information about the used material was available from literature and supplier, the dielectric properties of the photopolymer resin were characterized. Moreover, in the view of challenging further the SLA capability, several prototypes, based on the cross star shaped geometry but exhibiting a twist of variable angles along the longitudinal axis, were fabricated and tested. In order to compare the antennas performance in relation to the material volume and sizes, rectangular and cylindrical DRAs were also realized using same material and technology. Scattering parameter S11, gain, bandwidth (BW), efficiency and co- and cross-polarization of all antennas were measured. The experimental results showed that twisted S-DRAs exhibit same performance of the basic cross-starred-shaped antenna, due to the invariance to symmetry of the basic Gielis geometry. The measured gain is about 2.5 dB over a range of 1 GHz in the frequency range of interest; the BW measured for all S-DRAs is about 10%, whereas the efficiency is about 80% at 3.5 GHz. Finally, better performance in terms of bandwidth is shown by the S-DRAs, considering their dramatic volume reduction (~85%) compared to classic rectangular and cylindrical DRAs and other DRA examples already reported in the state of the art.

/pdf/design-and-manufacturing-of-super-shaped-dielectric-3uyvq6l4dt.pdf

Design and Manufacturing of Super-Shaped Dielectric Resonator Antennas for 5G Applications Using Stereolithography

An ultra wideband “OM” shaped DRA with a defected ground structure and dual polarization properties for 4G/5G wireless communications

Until the 1980s, shielded dielectric resonators (DRs) were used as high-quality factor energy storage devices for filter and oscillator applications [1]. Later, they gained status as effective radiators due to the efforts of Long, McAllister, and Chen [2]. Since then, enormous DR antenna (DRA) designs have been explored and different feeding techniques introduced to achieve optimum antenna characteristics like high gain and low quality factor (Q-factor), etc. Compared to microstrip antennas, DRAs offer attractive features such as low loss, high efficiency, and wide impedance bandwidth (BW). Low-profile design and BW enhancement are two important aspects of effective antenna synthesis. Various BW enhancement techniques-like the compact slot DRA [3], aperture feeding, perturbation, cavity-backed disk, ring-shaped DRA, and the stacking of two or more dielectric layers [4]-can be applied on DRAs for this purpose. The stacked DRA, dual-segment, hybrid DRA, and slots in ground-plane approaches were also well suited to improve the impedance BW of DRA [5]-[10]. Various multilayer cylindrical DRA (MCDRA) structures have been proposed and investigated for BW enhancement like the stacked cylinder approach [11], [12], slotted coaxial layered structure [13], etc. More recently, various fractal geometries have been introduced for antenna applications. The main objective of fractal applications is to reduce the size of the antenna for wideband characteristics, while maintaining other design parameters at an acceptable level. Several antenna configurations based on fractal geometries have been previously examined [14].

A Low-Profile Multilayer Cylindrical Segment Fractal Dielectric Resonator Antenna: Usage for wideband applications

In this paper, a novel two-segment rectangular dielectric resonator antenna is designed for ultra-wide application. These dielectric resonator antennas, having different dielectric material, are placed side by side and are excited with common micro-strip feed. Further, the effect of defected ground is also investigated. The proposed structure offers a wide bandwidth of 131.24% for |S11| < –10 dB from 2.8–13.49 GHz catering needs of many wireless applications for S-band, C-band, X-band, WLAN, and WiMAX. The proposed antenna is fabricated and tested to validate the simulated results. This antenna exhibits a maximum gain of 7.2 dBi at 10 GHz along with 95% of peak efficiency at 3 GHz.

A two-segment rectangular dielectric resonator antenna for ultra-wideband application

In this paper, a novel conformal-strip excited asymmetric rectangular dielectric resonator antenna with a defected ground is proposed for ultra-wide band application. The material used for investig...

Novel design of conformal-strip excited asymmetrical rectangular dielectric resonator antenna for ultra-wide band application

In this paper, an inverted pyramid-shaped Sierpinski fractal Dielectric Resonator Antenna (DRA) is designed and investigated. The geometry is a Sierpinski Gasket with rectangle as a base element. P...

Sierpinski fractal inspired inverted pyramidal DRA for wide band applications

In this paper, two fractals are combined and applied on a half hemispherical DRA for good impedance bandwidth. Here, the GP-Series Fractal and Minkowski Fractal are performed on proposed antenna which includes three steps of iteration and gives the enhanced peak gain and efficiency in result. The HDRA is made up of commercially available dielectric constant 4.3 (FR-4 lossy) and it has dissipation factor, $\mathbf{tan}\ \boldsymbol{\delta}=0.025$ . The fractal Half-HDRA is excited by a co-axial probe feeding at an offset value of $\mathbf{x} =8.05$ mm and $\mathbf{y}=5.1$ mm. The simulated impedance bandwidth of the final iteration in Minkowski Fractal is 52.5% i.e. 5.3 GHz to 9.1 GHz (S 11 below −10 dB). The main purpose of this work is to observe the effect of two combined Fractal geometry and to compare its Fractional Bandwidth, Gain, and Efficiency.

Shubha Gupta

Papers

A Low-Profile Multilayer Cylindrical Segment Fractal Dielectric Resonator Antenna: Usage for wideband applications

A two-segment rectangular dielectric resonator antenna for ultra-wideband application

Novel design of conformal-strip excited asymmetrical rectangular dielectric resonator antenna for ultra-wide band application

Sierpinski fractal inspired inverted pyramidal DRA for wide band applications

A Compact Half-Hemispherical DRA with two combined Fractal Approach