Exciting the Low Permittivity Dielectric Resonator Antenna Using Tall Microstrip Line Feeding Structure and Applications

The development of wireless communications increases the challenges on antenna performance to improve the capability of the whole system. New fabrication technologies are emerging that not only can improve the performance of components but also provide more options for materials and geometries. One of the advanced technologies, referred to as deep X-ray lithography (XRL), can improve the performance of RF components while providing interesting opportunities for fabrication. Since this fabrication technology enables the objects of high aspect ratio (tall) structure with high accuracy, it offers RF/microwave components some unique advantages, such as higher coupling energy and compacted size. The research presented in that thesis investigates the properties of deep XRL fabricated tall microstrip transmission line and describes some important features such as characteristic impedance, attenuation, and electromagnetic field distribution. Furthermore, since most of traditional feeding structure cannot supply enough coupling energy to excite the low permittivity DRA element (εr≤10), three novel feeding schemes composed by tall microstrip line on exciting dielectric resonator antennas (DRA) with low permittivity are proposed and analyzed in this research. Both simulation and experimental measured results exhibit excellent performance. Additionally, a new simulation approach to realize Dolph-Chebyshev linear series-fed DRA arrays by using the advantages of tall microstrip line feeding structure is proposed. By using a novel T shape feeding scheme, the array exhibits wide band operation due to the low permittivity (εr=5) DRA elements and good radiation pattern due to the novel feeding structure. The tall metal transmission line feed structure and the polymer-based DRA elements could be fabricated in a common process by the deep XRL technology. This thesis firstly illustrates properties and knowledge for both DRA element and the tall transmission line. Then the three novel feeding schemes by using the tall transmission line on exciting the low permittivity DRA are proposed and one of the feeding structures, side coupling feeding, is analyzed through the simulation and experiments. Finally, the T shape feeding structure is applied into low permittivity linear DRA array design work. A novel method on designing the Dolph-Chebyshev array is proposed making the design work more efficient

The Development of Mathematical Modelling Representing Tuning Slot Parameters Versus Resonant Frequency

To design a Dielectric Resonator Antenna (DRA) with desired resonant frequency, Heuristic method must be used. Thus, it consume a lot of time, effort and cost. It is because, currently there are no specific mathematical model to determine the resonant frequency. Eventhough, the resonant frequency can be obtained through simulation, but it will consume a lot of time an effort. Hence, this project is carried out to develop mathematical model which represent tuning slot parameters of DRA versus resonant frequency. The tuning slot parameters varied in this project is C-slot position from input port of antenna. The position of the slot from the input port of the antenna have been varied and resonant frequency at each position is determined. A series of preliminary simulation and design have been performed by utilizing CST Microwave Studio Software. From the simulations, the relationship between the C-slot position and resonant frequency is studied and a mathematical model is developed

Design and Analysis of Singly Fed Dielectric Resonator Antenna with A Wideband Circular Polarization

The proliferation of mobile communications technology increases the demands for faster and more robust services, in addition to the ever decreasing sizes of antennas. These demands can be satisfied using circularly polarized (CP) dielectric resonator antennas (DRAs) exhibiting wide operational bandwidth capability. By utilizing such antennas, the probability of linking the transmitted and received signals is higher, and the system is more reliable since the CP wave is transmitted in all planes and less susceptible to unwanted reflections and absorptions. As CP system is insensitive to the transmitter and receiver orientation, the time consuming practice of continuously aligning the antennas can be avoided. Furthermore, the antennas profile can be reduced simply by using dielectric material with higher permittivity. The thesis focuses on the design and analysis of singly-fed regular-shaped DRAs with a wideband circular polarization. Two new single-point excitation schemes that can be easily used to excite an arbitrarily shaped DRA are introduced, where a square spiral and a rectangular open half-loop are used for DRA excitation. These proposed feeding methods are based on employing conformal conducting metal strips that are placed on the DRA surface. Additionally, two different approaches are employed onto the DRA design to enhance the CP bandwidth. The first approach is based on using a multilayer dielectric, and the second introduces a parasitic half-loop inside the feeding element. The generated broad CP bands have been achieved in conjunction with sufficient impedance matching bandwidths. The studied geometries have been modeled using a comprehensive self developed MoM code that employs the volume surface integral equation (VSIE). The computed results have been validated against those obtained from measurements as well as CST microwave studio simulations. Theoretical and experimental results demonstrate a several folds enhancement in the CP bandwidths compared to those reported in the literature for identical DRA geometries

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

Design and analysis of dielectric resonator antenna

Present scenario of communication, all wired ones becoming as wireless. So, to achieve efficient and affordable communication in wireless technology, compact and efficient radiators required. One of the efficient radiators is dielectric resonator antenna (DRA). Almost all the applied power will be lost in the radiated fields only, with this attractive feature DRAs become much popular in wireless communication field at microwave frequencies. In this project, new type of DRAs designed for popular wireless applications like Wireless Interoperability Microwave Access (WIMAX), Wireless Local Area Network (WLAN) and Wireless Fidelity (Wi-Fi). This project covers the design of DRA which including all parametric studies of the return loss, radiation patterns, gain and directivity for specific wireless application. Due to this flexibility in DRAs, they can be designed with different shapes as per coverage requirements depending upon the applications in the wireless communication industries. Here, all the designed DRAs are excited by using Co-planar waveguide (CPW) feeding technique, having advantageous features (less radiation leakage, operating at extremely high frequencies). Among four designed DRAs, first two DRAs having single Dielectric Resonator (DR) element and radiating at 2.4 GHz and 5.8 GHz and rest of two designs having stacked method. Here, the concept of stacking is used to get the multiple resonant frequencies and wide bandwidths. The first stacked DRA is covering the resonant frequencies at 5.20GHz, 5.84GHz which covers WLAN bands and second stacked DRA resonating at 3.5GHz and 5.5GHz, which covers Wi-MAX and WLAN bands respectively. This project work concludes that, the designed DRAs efficiently radiates at IEEE 802.11a/b/g and IEEE-802.16 bands

Dielectric resonator antenna for Short Range Wireless Communication Applications

Present scenario of communication, all wired ones replacing with wireless. So, to achieve efficient communication in wireless technology, efficient radiators required. One such efficient radiators is Dielectric resonator antenna. The extremely wide spectrum of 3.1 to 10.6 GHz with 15 bands of bandwidth greater than 500 MHz and power limit less than -41.3 dBm/MHz announced by FCC for Ultra wide band. The release of this Spectrum has rapidly increased the research in UWB technology for communications, radar imaging, and localization applications. Radio systems based on UWB technology offer opportunities for transmission of high data rate signals, coding for security and low probability of intercept, especially in multi user network applications .DRA is one of the best antennas for UWB applications due to its attractive features like high radiation efficiency, low dissipation loss, small size, light weight, and low profile. Moreover, DRAs which possess a high degree of design flexibility, have emerged as an ideal candidate for wide band, high efficiency, and cost-effective applications. Second antenna is designed which resonates at 5.5 GHz which is suitable for 802.11a WLAN applications.Third antenna is designed to resonate at two different frequencies one at 2.42 GHz and other at 9.13 GHz

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

Design and Optimisation of Dielectric Resonator Antenna array using PSO Technique

This thesis presents design and optimization of Dielectric Resonating Antenna array using PSO technique for wireless application. The designing of the DRA is done in Computer Simulation Technology(CST) microwave studio. The DRA is designed using two disk shaped resonator made from a ceramic material(Ceramic batch #QC1266470) whose dielectric constant is 34.73, FR-4 substrate whose dielectric constant is 4.5 and copper patch. Two dielectric resonators are represented as an array. The resonators are fed by Microstrip transmission line model. The resonating frequency of resonators is 2.4 Ghz. The length of the Microstrip transmission line is ë/4 where ë is the resonator wavelength. The simulation process is done using the same Computer Simulation Technology (CST) Microwave Studio Suite and then the design has been optimized using a Particle Swarm Optimization (PSO) technique to get the desired resonating frequency. The DRA is operating at the frequency bands used for IEEE 802.11b/g Wireless LANs