Dielectric Resonator Antennas: Applications and developments in multiple-input, multiple-output technology

This article presents a comprehensive review of multiple-input, multiple-output (MIMO) dielectric resonator antennas (DRAs) that have evolved in the past decade. In addition to the major challenges faced during designing an MIMO DRA, this article also discusses research gaps that must be filled in the future. Exploring the advantages of DRAs, numerous novel designs have been proposed in the last few years

Dual band rectangular dielectric resonator antenna for WLAN application

A compact dual band ring shape rectangular dielectric resonator antenna (RRDRA) to operate at 2.4 GHz and 5 GHZ WLAN application is proposed. In this design the dielectric resonator is fed by modified 50Ω trapezoidal micro strip line situated on top of the FR4 substrate. The simulated and measured impedance bandwidth achieved at 2.4 GHZ is 12.42% (2.3149-2.6132) and 12.9% (2.21-2.52) respectively; whilst for 5 GHZ at 13% (5.1795-5.8914) and 13.2% (5.08-5.81) for S11<-10 dB. And the gain of the proposed antenna is 4.9dBi and 5.9 dBi at 2.4 GHz 5GHZ respectively. Results are simulated using Ansoft High frequency structural simulator (HFSS) for the study of impedance bandwidth, return loss, radiation pattern and antenna gain. Furthermore the antenna has been fabricated and tested. The measured characteristics of the proposed antenna are in good agreement with the simulated results

A nested square-shape dielectric resonator for microwave band antenna applications

In this paper, a nested square-shape dielectric resonator (NSDR) has been designed and investigated for antenna applications in the microwave band. A solid square dielectric resonator (SSDR) was modified systematically by introducing air-gap in the azimuth (ϕ-direction). By retaining the square shape of the dielectric resonator (DR), the well-known analysis tools can be applied to evaluate the performance of the NSDR. To validate the performance of the proposed NSDR in antenna applications, theoretical, simulation, and experimental analysis of the subject has been performed. A simple microstrip-line feeding source printed on the top of Rogers RO4003 grounded substrate was utilized without any external matching network. Unlike solid square DR, the proposed NSDR considerably improves the impedance bandwidth. The proposed antenna has been prototyped and experimentally validated. The antenna operates in the range of 12.34GHz to 21.7GHz which corresponds to 56% percentage bandwidth with peak realized gain 6.5dB. The antenna has stable radiation characteristics in the broadside direction. A close agreement between simulation and experimental results confirms the improved performance of NSDR in antenna applications

Small Multi-Band Rectangular Dielectric Resonator Antennas for Personal Communication Devices

The design of a novel rectangular dielectric resonator antenna (DRA) for multi-band application has been presented in this paper. The presented antenna has been composed of very low cost and relatively low dielectric constant substrate materials while three-segment thin dielectrics with different sizes have been used and separated by two metal plates in order to set the four different frequency bands. The proposed quad-band antenna operates at 2.4/3.5/5.2 &amp; 5.8 GHz. The radiation pattern, gain and VSWR of this antenna show very good operation for this antenna in all frequency bands. The first method based on finite element method (FEM) and the second one based on finite integral technique (FIT) have been used to analyze antenna structure, and subsequently the Genetic Algorithm (GA) has been applied by using HFSS simulator to obtain the optimized parameters.DOI:http://dx.doi.org/10.11591/ijece.v4i1.457

Compact ultra-wideband dielectric resonator antennas

UWB communication systems were newly regenerated when the Federal Communications Commission (FCC) defined the 3.1-10.6 GHz unlicensed band for UWB applications. Based on an investigation in designing UWB antennas, researchers have encountered more difficulties compared to a narrow band antenna. UWBantennas should have extremely wide impedance bandwidth while preserving high radiation efficiency with compact size. In some cases, a band-notched function should have been created to avoid electromagnetic interference between nearby existing systems and UWB systems. In this research, various promising UWB Dielectric Resonator Antennas (DRAs) have been demonstrated to overcome several challenges. The impedance bandwidth of the UWB DRAs has been improved for more than 110% by using some techniques such as connecting a strip to the ground plane and modifying structure of Dielectric Resonator (DR). The efficiency issue of UWB antennas is overcome by implementing DR as a resonator element which is excited by various shape structures feed lines to achieve more than 90% efficiency. The electromagnetic interferences between UWB systems and nearby existing systems in the frequency bands of 3.22-4.06 GHz, 4.84-5.96 GHz and 5.71-6.32 GHz are eliminated by using a stub connected to the hollow centre of feed line, an inverted-T shape parasitic strip near DR and modified metallic sheet underneath the DR, respectively. Compared with UWB monopole antennas, UWB DRAs obviate the problem of radiation pattern by utilizing dielectric resonator characteristics. In parallel, the broadside radiation pattern is obtained by implementing various shapes of microstrip feed line at a proper location to excite the DRA that provides symmetry radiation patterns with a consistent stability across the desired bandwidth

Photoresist-based polymer resonator antennas (PRAs) with lithographic fabrication and dielectric resonator antennas (DRAs) with improved performance

The demand for higher bit rates to support new services and more users is pushing wireless systems to millimetre-wave frequency bands with more available bandwidth and less interference. However at these frequencies, antenna dimensions are dramatically reduced complicating the fabrication process. Conductor loss is also significant, reducing the efficiency and gain of fabricated metallic antennas. To better utilize millimetre-wave frequencies for wireless applications, antennas with simple fabrication, higher efficiency, and larger impedance bandwidth are required. Dielectric Resonator Antennas (DRAs) offer many appealing features such as large impedance bandwidth and high radiation efficiency due to the lack of conductor and surface wave losses. DRAs also provide design flexibility and versatility. Different radiation patterns can be achieved by different geometries or resonance modes, wideband or compact antennas can be provided by different dielectric constants, and DRAs can be excited by a wide variety of feeding structures. Nevertheless, compared to their metallic counterparts, fabrication of DRAs is challenging since they have traditionally been made of high permittivity ceramics, which are naturally hard and extremely difficult to machine and cannot be easily made in an automatic way. The fabrication of these three dimensional structures is even more difficult at millimetre-wave frequencies where the size of the antenna is reduced to the millimetre or sub-millimetre range, and tolerances to common manufacturing imperfections are even smaller. These fabrication problems restrict the wide use of DRAs, especially for high volume commercial applications. A new approach to utilize the superior features of DRAs for commercial applications, introduced in this thesis, is to exploit polymer-based resonator antennas (PRAs), which dramatically simplifies fabrication due to the natural softness and results in a wide impedance bandwidth due to the low permittivity of polymers. Numerous polymer types with exceptional characteristics can be used to fulfill the requirements of particular applications or achieve extraordinary benefits. For instance, in this thesis photoresist polymers facilitate the fabrication of PRAs using lithographic processes. Another advantage derived from this approach is the capability of mixing polymers with a wide variety of fillers to produce composite materials with improved or extraordinary characteristics. The key contributions of this thesis are in introducing SU-8 photoresist as a radiating material, developing three lithographic methods to fabricate photoresist-ceramic composite structures, introducing a simple and non-destructive measurement method to define electrical properties of the photoresist composites, and demonstrating these structures as improved antenna components. It is shown that pure SU-8 resonators can be highly efficient antennas with wideband characteristics. To achieve more advantages for RF applications, the microwave properties of photoresists are modified by producing ceramic composite materials. X-ray lithography fabrication is optimized and as a result one direct and two indirect methods are proposed to pattern ultra thick (up to 2.3 mm) structures and complicated shapes with an aspect ratio as high as 36:1. To measure the permittivity and loss tangent of the resulting materials, a modified ring resonator technique in one-layer and two-layer microstrip configurations is developed. This method eliminates the requirement to metalize the samples and enables characterization of permittivity and dielectric loss in a wide frequency range from 2 to 40 GHz. Various composite PRAs with new designs (e.g. frame-based and strip-fed structures) are lithographically fabricated, tested, and discussed. The prototype antennas offer -10 dB bandwidths as large as 50% and gain in the range of 5 dBi

Impedance Transformers

Non

UWB Technology

Ultra Wide Band (UWB) technology has attracted increasing interest and there is a growing demand for UWB for several applications and scenarios. The unlicensed use of the UWB spectrum has been regulated by the Federal Communications Commission (FCC) since the early 2000s. The main concern in designing UWB circuits is to consider the assigned bandwidth and the low power permitted for transmission. This makes UWB circuit design a challenging mission in today's community. Various circuit designs and system implementations are published in this book to give the reader a glimpse of the state-of-the-art examples in this field. The book starts at the circuit level design of major UWB elements such as filters, antennas, and amplifiers; and ends with the complete system implementation using such modules

Design and Analysis of Dielectric Resonator Antennas For WLAN Applications

The increasing use of wireless mobile communication systems demand the antennas for different systems and standards with properties like reduced size, broadband, multi band operation, moderate gain etc. The planar and dielectric resonator antennas are the present day antenna designer’s choice. However, micro strip and Dielectric resonator antennas inherently have a narrow bandwidth. Since the Federal Communications Commission (FCC) first approved rules for the commercial use of ultra-wideband (UWB) in 2002, the experiments on ultra wide band (UWB) systems have been expanding rapidly. In this thesis, a low-cost compact microstrip line-fed antenna with parasitic patches resulting a Ultra-Wideband characteristics with a band dispensation is presented. The antenna was implemented on FR4 substrate with a thickness of 1.6mm & relative permittivity (µr) of 4.3 .It has a partial ground plane .The antennas is exited by microstrip line feed. The proposed antenna is a Rectangular shape , “T” shape,& “ð” shape made of Teflon of permittivity (µr) of 2.1& compare with “ð” shape made of Roger of permittivity (µr) of 10.2 .The proposed antenna is simulated with CST Studio 2011. The return loss results and radiation pattern plots of the antenna are included in this thesis