Enhanced transmission of electromagnetic waves through split-ring resonator-shaped apertures

The design of aperture shape is a promising approach for enhanced transmission through a subwavelength aperture. We designed split-ring-resonator (SRR)-shaped apertures in order to increase the transmission through subwavelength apertures by making use of the strong localization of the electromagnetic field in SRR-shaped apertures. We obtained a promising result of 104-fold enhancement by utilizing SRR-shaped apertures. It is possible to use these proposed structures at optical frequencies by making several modifications such as decreasing the sharpness of edges and increasing the gap width. Since SRRs are already being realized at optical frequencies, our proposed SRR-shaped aperture structures are promising candidates for novel applications

Design and Analysis of a Cylindrical Dielectric Resonator Antenna Array and Its Feed Network

There is an ever increasing need for smaller, lighter, more efficient antennas for commercial and military applications. One such antenna that meets these requirements is the dielectric resonator antenna (DRA). In recent years there has been an abundance of research on the utilization of the DRA as a radiating element. However, its practical application - especially pertaining to DRA arrays - is still considered to be at its infancy. The purpose of this work is to present a systematic process to be used in the design, simulation, optimization, fabrication, and testing of a cylindrical DRA array including its associated feed network. The DRA array development cycle begins with a single cylindrical radiating element. ComDRA parameters such as DRA radius, feed type, feed location, and element spacing are investigated. A DRA element in this research is optimized for bandwidth and gain for use at x-band (8-12 GHz). The antenna feed network, being an integral part of all antenna arrays, is also considered. The primary causes of impedance mismatch in the feed network are identified and techniques to improve performance are explored. An improvement in impedance bandwidth is gained through traditional transmission line matching methods. Ultimately, a 16 (4x4) element and 256 (16x16) element array is fabricated, tested, and compared to an existing commercial technology

Design and Analysis of Dual-Linearly Polarized Dielectric Resonator Antenna Array

Dielectric resonators have been widely used as narrowband shielded circuit components. The dielectric resonator antenna is an implementation of using an unshielded dielectric structure in order to extract the radiation of electric fields. Dielectric materials can have low dielectric loss and the absence of metallic surfaces also reduces conduction losses. A dielectric resonator antenna can have efficiencies above 95% for several hundred megahertz. The versatility in choice of shape, relative permittivity and size enables a whole spectrum of operating frequency ranges (1GHz-40GHz), sizes, radiation patterns and bandwidths. The far field radiation pattern is a characteristic of the resonating modes. In this project the investigation of dielectric resonator antennas was quantitatively realized by the design and evaluation of one omni-directional wideband dielectric resonator antenna with operating frequency range 3.9GHz to 6.2GHz and two dual linearly polarized broadside antenna arrays in L, S and C band applications. Transverse modes with rotational symmetry are preferred for an omni-directional radiation pattern, whereas a hybrid mode is suitable for a broadside radiation pattern. The modes can be excited by feeding from microstrip lines and coaxial probes. The location of the excitation determines what mode is excited. The resonant frequency is controlled by size, shape and permittivity of the DR element. Dual polarization is achieved by exciting two orthogonal modes simultaneously in the resonator. The cross coupling between the feeding networks and the matching of these becomes a crucial step in the design of a dielectric resonator antenna. The broadside antenna elements have been arranged in a linear as well as planar array to increase the directivity

Investigation of The Microstrip Line Feeder Effect to Resonant Frequency

This paper presents a study on the investigation on the microstip line feeder effect to its resonant frequency. The application of the cylindrical DRA (CDRA) and microstrip line is used to observe the relationship between these two variables. The microstip line will be varied according to the width and the length of the microstrip. All designs are simulated by using the Computer Simulation Technology (CST) software in order to get the desired resonant frequency and the bandwidth of the microstrip line design. Tuning of the resonant frequency is made if the designs are not achieving the desired outcome. The optimum parameter of the CDRA and microstrip line design is analyzed to obtain the operating frequency between ranges of 4 GHz to 5 GHz application. The simulation and measuring the project prototype is made to analyze the results and observe the comparisons between theoretical and experimental values. From this, the design optimum performance of the antenna can be improved and obtained at the end of the project period

Glueless Multiple Input Multiple Output Dielectric Resonator Antenna with Improved Isolation

In this dissemination, a glueless compact dual port dielectric resonator antenna (DRA) is proposed for X-band applications. A prototype has been fabricated with RT Duroid substrate and Eccostock (ϵr = 10)-made DRA. The ring shaped DRA is excited by aperture coupled feeds maintaining symmetry between both the ports. Four cylindrical copper rods with four strips have been used to fix the DRA on the substrate and provide additional mechanical stability. Eight copper strips are used to provide impedance matching and impedance bandwidth (IBW) widening. The measured IBW of dual port DRA is 10.5% (8.05–8.95 GHz) and maximum gain of radiator is 6.2 dBi. The proposed antenna becomes compact when the net volume of DRA is approximately 3.5 cm3 and the volume of the substrate is 2.88 cm3, with a surface area of 36 cm2 and operating in X-band, which finds applications in satellite communication, weather radar, synthetic aperture radar, and telemetry tracking and control

Design and Implementation of an Integrated Solar Panel Antenna for Small Satellites

Thesis (PhD (Electrical Engineering))--Cape Peninsula University of Technology, 2019This dissertation presents a concept for a compact, low-profile, integrated solar panel antenna for use on small satellites in low Earth orbit. To date, the integrated solar panel antenna design approach has primarily been, patch (transparent or non-transparent) and slot radiators. The design approach presented here is proposed as an alternative to existing designs. A prototype, comprising of an optically transparent rectangular dielectric resonator was constructed and can be mounted on top of a solar panel of a Cube Satellite. The ceramic glass, LASF35 is characterised by its excellent transmittance and was used to realise an antenna which does not compete with solar panels for surface area. Currently, no closed-form solution for the resonant frequency and Q-factor of a rectangular dielectric resonator antenna exists and as a first-order solution the dielectric waveguide model was used to derive the geometrical dimensions of the dielectric resonator antenna. The result obtained with the dielectric waveguide model is compared with several numerical methods such as the method of moments, finite integration technique, radar cross-section technique, characteristic mode analysis and finally with measurements. This verification approach was taken to give insight into the resonant modes and modal behaviour of the antenna. The interaction between antenna and a triple-junction gallium arsenide solar cell is presented demonstrating a loss in solar efficiency of 15.3%. A single rectangular dielectric resonator antenna mounted on a ground plane demonstrated a gain of 4.2 dBi and 5.7 dBi with and without the solar cell respectively. A dielectric resonator antenna array with a back-to-back Yagi-Uda topology is proposed, designed and evaluated. The main beam of this array can be steered can steer its beam ensuring a constant flux density at a satellite ground station. This isoflux gain profile is formed by the envelope of the steered beams which are controlled using a single digital phase shifter. The array achieved a beam-steering limit of ±66° with a measured maximum gain of 11.4 dBi. The outcome of this research is to realise a single component with dual functionality satisfying the cost, size and weight requirements of small satellites by optimally utilising the surface area of the solar panels

Standing-Wave Dielectric Array Antennas

Due to the evolutions in wireless communication systems, antenna engineers have been confronting a number of challenges regarding improving the performance of antennas, miniaturizing the size as well as considering the fabrication simplicity. Although dielectric resonator antennas typically suffer from exhibiting low gain, they have been thoroughly under investigating as they are being excellent candidates to be utilized to fulfill contemporary communication systems requirements and specifications, especially at high-frequency ranges. The reason behind this solicitude is because they have several advantageous features, including but not limited to the simplicity of the used excitation mechanism and fabrication easiness. One of the well-known methods to improve the gain is by arraying additional individual DRAs. However, one major obstacle evokes when designing the array to operate at a higher frequency. Spurious radiations from the feeding network are considerable and unfavorably influence the overall array performance. Moreover, it is mandatory to have several quarter-wavelength transmission lines and power dividers which, in turns, lead to high configuration complexity. The substantial intention of this dissertation is to explore dielectric resonator array antenna designs where the concept of standing waves is utilized. In contradictory to corporate-fed traveling-wave array antennas designs, the need to utilize microstrip discontinuities such as quarter-wave transformers or power dividers is eliminated while having a single feeding port to excite the entire array structure. Consequently, undesired spurious coupling and radiations can be exceedingly minimized especially when operating at very high-frequency bands. The dissertation proposes two novel dielectric array configurations based on the concept of standing-wave. In the first configuration, vertical and horizontal low-profile dielectric bridges have been employed to connect 3x3 dielectric array elements. The top surface of each bridge is covered by a metallic patch to prevent unfavorable radiations coming out of the bridges. The array structure is fed using a single coupling aperture resides symmetrically underneath the center element only. When exciting waves are coupled to the center element, these waves can be transferred to other array elements via the introduced dielectric bridges. Therefore, the entire structure resonates at the resonant frequency as a whole. The proposed design provides a realized gain of about 15 dBi at the boresight. The return loss is about -20 dB possessing about 35.7% useful impedance bandwidth. The experimental results show excellent agreement with those obtained by simulation. The second proposed configuration consists of four dielectric resonator antennas forming a linear array. On the top surface of the substrate and between the array elements, there are three metallic patches which are employed to excite the array elements. These patches are slightly extended under the slabs to allow sufficient coupling. Under each dielectric slab, there is one metallic patch reside symmetrically at the center to enhance the wave coupling in both directions toward the array elements. The single feeding coaxial probe is attached to the center patch, and its location was optimized to provide excellent impedance matching. The maximum observed gain is 15 dBi at the boresight. The array structure is well matched and the return loss is measured to be -45 dB. The validity and versatility of both designs are realized and illustrated. One powerful advantageous feature is that the feeding network was extremely simplified to a single port to excite the entire array structure. Another advantage is that both designs were partially fabricated using 3D printing technology. Therefore, it can be said that the proposed configurations are easy to fabricate since the complexity of designing feeding networks was obviated

A comprehensive survey on 'circular polarized antennas' for existing and emerging wireless communication technologies

Circular polarized (CP) antennas are well suited for long-distance transmission attainment. In order to be adaptable for beyond 5G communication, a detailed and systematic investigation of their important conventional features is required for expected enhancements. The existing designs employing millimeter wave, microwave, and ultra-wideband (UWB) frequencies form the elementary platform for future studies. The 3.4-3.8 GHz frequency band has been identified as a worthy candidate for 5G communications because of spectrum availability. This band comes under UWB frequencies (3.1-10.6 GHz). In this survey, a review of CP antennas in the selected areas to improve the understanding of early-stage researchers specially experienced antenna designers has presented for the first time as best of our knowledge. Design implementations involving size, axial ratio, efficiency, and gain improvements are covered in detail. Besides that, various design approaches to realize CP antennas including (a) printed CP antennas based on parasitic or slotted elements, (b) dielectric resonator CP antennas, (c) reconfigurable CP antennas, (d) substrate integrated waveguide CP antennas, (e) fractal CP antennas, (f) hybrid techniques CP antennas, and (g) 3D printing CP antennas with single and multiple feeding structures have investigated and analyzed. The aim of this work is to provide necessary guidance for the selection of CP antenna geometries in terms of the required dimensions, available bandwidth, gain, and useful materials for the integration and realization in future communication systems