Analysis and Design of Substrate Integrated Waveguide-based Antennas for Millimeter Wave Applications

Recently, there has been increasing interest and rapid growth in millimeter wave (MMW) antennas and devices for use in diverse applications, services and technologies such as short-range communication, future mm-wave mobile communication for the fifth generation (5G) cellular networks, and sensor and imaging systems. Due to the corresponding smaller wavelength, mm-wave frequencies offer the advantage of physically smaller antennas and circuits as well as the availability of much wider bandwidth compared to microwave frequencies. It is important to design millimeter wave antennas with high gain characteristics due to their high sensitivity towards atmospheric absorption losses. Moreover, millimeter wave antennas can have wide bandwidth and are suitable for applications in large frequency range. In this thesis, planar antennas are designed using substrate integrated waveguide (SIW) technology to have low losses, high quality factor, and low fabrication cost. Firstly, an antipodal fermi linear tapered slot antenna (AFLSTA) with sine corrugations at the side edges at 32.5 GHz is presented, which has a wide impedance bandwidth greater than 30 %, in order to support the high data rate channels. This antenna has a high gain of 12.6 dB and low side lobe levels (better than - 17 dB) in both E and H planes. This antenna is studied and analyzed in array and beamforming configurations to meet requirements of millimeter wave applications. In order to obtain high gain and narrow beamwidth pattern, a 1 × 8 AFLTSA array using SIW power divider network is presented. The design characteristics of the power divider network are presented in this thesis, which help in calculating the performance characteristics of this array structure. This array has an acceptable bandwidth of 14.7 % (30-35 GHz) with high gain of 20.4 dB and 8.35° 3 dB beamwidth. The side lobe levels are also improved using this SIW power divider network and are lower than -25 dB in E-plane and -15 dB in H-plane respectively. This antenna has a radiation efficiency greater than 93% over the whole bandwidth. The second research theme is beamforming of AFLTSA antenna. This beamforming is performed using multi-beam antenna concept in which the beam is rotated with a help of compact beamforming network and excitation from different input ports. The design methodology for 2 × 2 and 4 × 4 subarray beamforming networks is presented along with their current distributions illustrating the beamforming process. These subarrays possess wide impedance bandwidth between 29-36 GHz. Moreover, these subarrays are able to achieve gain between 12-15 dB with narrow beamwidth reaching till 11°. All the results along with the numerical data is presented in this thesis. This antenna is suitable candidate for millimeter wave wireless communications and imaging systems

High Gain Planar Antenna Structures for Ka-band Applications

Antennas are an essential part of a communication system as they control a coverage area of the signal. The millimeter wave band has the potential to offer numerous radio applications which require the large bandwidth channels. Due to the current cellular subscribers’ demand of higher data rates, even cellular communication is expected to move in millimeter wave communications at Ka band of 26.5 GHz to 40 GHz. However, millimeter waves are sensitive to the high degree of atmospheric and oxygen absorption losses. This challenge of the millimeter wave communication can be tackled by employing high gain antennas. In addition, modern electronic products require compact handheld devices to offer the user-friendly system as well as capture the market. Therefore, planar antenna structures are apt for these communication systems. In this thesis, two antenna structures are presented at the Ka band for millimeter wave communications. Initially, four element patch antenna is presented for high gain in the broadside direction. Patch elements are excited using an aperture coupling from 50Ω microstrip line. Air-gap cavity is used to improve the impedance bandwidth of the design. This structure obtains a relatively moderate impedance bandwidth of 4.6%. The proposed four-element patch antenna exhibits a flat gain over an operating band with 13.8 dB gain at the design frequency. The antenna achieves a wide beamwidth of 700 in H plane. In addition, side lobe levels in E and H planes are -14.5 dB and 23 dB respectively. For the second prototype, an Antipodal Fermi-Linear Tapered Slot Antenna (AFLTSA) is presented to achieve the wide impedance bandwidth with high flat gain for endfire radiation. Substrate Integrated waveguide (SIW) technique is utilized to feed the AFLTSA which reduces insertion losses of the structure. Fermi-Dirac distributed curve in conjunction with a linear curve for a tapered slot increases the coupling of the electric field from a substrate integrated waveguide to the tapered slot. Knife edge rectangular corrugation profile is used at edges of AFLTSA in order to reduce the side lobes and cross polarization levels of radiation pattern. The proposed structure achieves the wide impedance bandwidth to support requirements for high data rate channels. Measurement results from a fabricated prototype exhibit a flat gain over an entire operating frequency band with 16.4 dB gain at 28 GHz. The wide impedance bandwidth is achieved with return loss below 15 dB. Proposed structure has low side lobe levels of -13.9 dB in H plane and -19.5 dB in E plane. In addition, it offers a low cross polarization level of -22 dB

Millimeter-Wave Substrate Integrated Waveguide Antenna and Front-End Techniques for Gigabyte Point-to-Point Wireless Services

RÉSUMÉ La relativement faible absorption atmosphérique dans les bandes de fréquences E et W a permis le développement de nombreuses applications sans-fil. Les bandes de fréquences de 71-76 GHz, 81-86 GHz et 94.1-97 GHz sont toutes assignées au spectre de communication sans-fil gigabyte par la Federal Communication Commission (FCC) des États-Unis. Lorsque la fréquence augmente vers la région des ondes millimétriques, l’efficacité et la qualité des lignes micro-ruban sont affectées par de sérieuses pertes de transmission et par l’interférence inter-signaux. D’un autre côté, la technologie des guides d’ondes classique est demeurée populaire pour la conception de systèmes haute perfomance dans la bande E/W. Cependant, cette technologie n’est pas appropriée pour une production à grande échelle et à faible coût à cause de sa structure encombrante et coûteuse. De plus, la structure non-planaire des guide d’ondes rend difficile la connection à des composantes planaires actives ainsi qu’à d’autres lignes planaires telles que les lignes micro-ruban et les guides d’ondes coplanaires (CPW). Afin de remédier à ce problème, les circuits intégrés aux substrats (SIC) ont été proposés comme une solution à faible coût, à efficacité élevée, planaire et intégrée au substrat pour des applications à hautes-fréquences. Les guides d’ondes intégrés aux substrats (SIW), faisant partie de la famille des SIC, possède non seulement les avantages des guides d’ondes rectangulaires mais aussi d’autres bénéfices comme un faible coût, une petite taille, un poids léger et la facilité de fabrication par les techniques de fabrication des PCB ou d’autres techniques. Dans cette thèse, nous élargissons la recherche sur les SIW en proposant et développant une variété d’antennes innovatrices, de réseaux d’antennes et de composantes passives millimétriques qui sont appliqués à la conception et à la démonstration de réseaux d’antennes intégrés et d’étages d’entrée de systèmes de communication en bande E/W. Les contributions scientifiques principales du présent travail peuvent être résumées comme suit: Un réseau d’antenne 4x4 utilisant la technologie des guides d’ondes intégrés au substrat (SIW) pour la conception de son réseau d’alimentation est proposé et démontré. Des fentes longitudinales gravées sur la surface métallique du dessus du SIW sont utilisées pour alimenter les éléments du réseau d’antennes. Des cubes composés d’un matériau diélectrique à faible permittivité sont placés au-dessus de chaque réseau d’antenne 1x4 afin d’augmenter le gain des antennes patch. La largeur de bande de deux réseaux d’antennes 4x4 est d’environ 7.5 GHz (94.2-101.8 GHz) avec un gain de 19 dBi.----------ABSTRACT The relatively low atmospheric absorption over E-band and W-band (frequency window) has been spurred many wireless applications. Frequency bands of 71-76 GHz, 81-86 GHz, and 94.1-97 GHz are all allocated by the US Federal Communication Commission (FCC) as parts of gigabyte wireless spectrum. As frequency increases to millimeter wave region, the efficiency and quality of microstrip lines suffer from serious transmission losses and signal interferences. On the other hand, classical waveguide technology has been popular in the design of high-performance millimeter-wave systems at E/W-band. However, this technology is not suitable for low-cost and mass production because of its expensive and bulky structure. In addition, the non-planar structure of waveguide makes it difficult to get connected to planar active components and other planar lines such as microstrip line and coplanar waveguide (CPW). To overcome this bottleneck problem, substrate integrated circuits (SICs) have been proposed as low-cost and high-efficient integrated planar structures for high-frequency applications. Substrate integrated waveguide (SIW), which is part of the SICs family, has manifested not only the advantages of rectangular waveguide but also other benefits such as low cost, compact size, light weight, and easy fabrication using PCB or other processing techniques. In this Ph.D. thesis, we extend the research of SIW to the proposal and development of various innovative antennas, antenna arrays and millimetre-wave passive components, which are applied to the design and demonstration of integrated antenna arrays and E/W-band front-end sub-systems. The principal scientific contributions of this thesis work can be summarized in the following: A 4×4 antenna array is proposed and demonstrated using substrate-integrated waveguide (SIW) technology for the design of its feed network. Longitudinal slots etched on the SIW top metallic surface are used to drive the array antenna elements. Dielectric cubes made of low-permittivity material are placed on top of each 1×4 antenna array to increase the gain of circular patch antenna elements. Measured impedance bandwidths of two 4×4 antenna arrays are about 7.5 GHz (94.2–101.8 GHz) with 19 dBi gain. Design of planar dielectric rod antenna is proposed and studied, which is fed by Substrate Integrated Non-Radiative Dielectric (SINRD) waveguide. This antenna presents numerous interesting features such as broad bandwidth (94-104 GHz), relatively high and stable gain, use of high dielectric constant substrate, and substrate-oriented end-fire radiation

Enabling Solutions for Integration and Interconnectivity in Millimeter-wave and Terahertz Systems

Recently, Terahertz (THz) systems have witnessed increasing attention due to the continuous need for high data rate transmission which is mainly driven by next-generation telecommunication and imaging systems. In that regard, the THz range emerged as a potential domain suitable for realizing such systems by providing a wide bandwidth capable of achieving and meeting the market requirements. However, the realization of such systems faces many challenges, one of which is interconnectivity and high level of integration. Conventional packaging techniques would not be suitable from performance perspective above 100 GHz and new approaches need to be developed. This thesis proposes and demonstrates several approaches to implement interconnects that operate above 100 GHz. One of the most attractive techniques discussed in this work is to implement on-chip coupling structures and insert the monolithic microwave integrated circuit (MMIC) directly into a waveguide (WG). Such approach provides high level of integration and eliminates the need of galvanic contacts; however, it suffers from a major drawback which isthe propagation of parasitic modes in the circuit cavity if the MMIC is large enough to allow such modes to propagate. To mitigate this problem, this work suggests and investigates the use of electromagnetic bandgap (EBG) structures that suppresses those modes such as bed of nails and mushroom-type EBG structures. The proposed techniques are used to implement several on-chip packaging solutions that have an insertion loss as low as 0.6 dB at D-band (110-170 GHz). Moreover, the solutions are demonstrated in several active systems using various commercial MMIC technologies. The thesis also investigates the possibility of utilizing the commercially available packaging technologies such as Embedded Wafer Level Ball Grid Array (eWLB) packaging. Such technology has been widely used for integrated circuits operating below 100 GHz but was not attempted in the THz range before. This work attempts to push the limits of the technology and proposes novel solutions based on coupling structures implemented in the technology’s redistribution layers. The proposed solutions achieve reasonable performance at D-band that are suitable for low-cost mass production while allowing heterogeneous integration with other technologies as well. This work addresses integration challenges facing systems operating in the THz range and proposes high-performance interconnectivity solutions demonstrated in a wide range of commercial technologies and hence enables such systems to reach their full potential and meet the increasing market demands

Design and Implementation of High Gain 60 GHz Antennas for Imaging/Detection Systems

Recently, millimeter wave (MMW) imaging detection systems are drawing attention for their relative safety and detection of concealed objects. Such systems use safe non-ionizing radiation and have great potential to be used in several applications such as security scanning and medical screening. Antenna probes, which enhance system performance and increase image resolution contrast, are primarily used in MMW imaging sensors. The unlicensed 60 GHz band is a promising band, due to its wide bandwidth, about 7 GHz (57 - 64 GHz), and lack of cost. However, at 60 GHz the propagation loss is relatively high, creating design challenges for operating this band in MMW screening. A high gain, low profile, affordable, and efficient probe is essential for such applications at 60 GHz. This thesis’s focus is on design and implementation of high gain MMW probes to optimize the performance of detection/imaging systems. First, single-element broadside radiation microstrip antennas and novel probes of endfire tapered slot high efficient antennas are presented. Second, a 57-64 GHz, 1 × 16-element beam steering antenna array with a low-cost piezoelectric transducer controlled phase shifter is presented. Then, a mechanical scanner is designed specifically to test proposed antenna probes utilizing low-power 60 GHz active monostatic transceivers. The results for utilizing proposed 60 GHz probes show success in detecting and identifying concealed weapons and explosives in liquids or plastics. As part of the first research theme, a 60 GHz circular patch-fed high gain dielectric lens antenna is presented, where the prototype’s measured impedance bandwidth reaches 3 GHz and a gain of 20 dB. A low cost, 60 GHz printed Yagi antenna array was designed, optimized, fabricated and tested. New models of the antipodal Fermi tapered slot antenna (AFTSA) with a novel sine corrugated (SC) shape are designed, and their measured results are validated with simulated ones. The AFTSA-SC produces a broadband and high efficiency pattern with the capacity for high directivity for all ISM-band. Another new contribution is a novel dual-polarized design for AFTSA-CS, using a single feed with a pair of linearly polarized antennas aligned orthogonally in a cross-shape. Furthermore, a novel 60 GHz single feed circularly polarized (CP) AFTSA-SC is modeled to radiate in the right-hand circularly polarized antenna (RHCP). A RHCP axial ratio bandwidth of < 3dB is maintained from 59 to 63 GHz. In addition, a high gain, low cost 60 GHz Multi Sin-Corrugations AFTSA loaded with a grooved spherical lens and in the form of three elements to operate as the beam steering antenna is presented. These probes show a return loss reduction and sidelobes and backlobe suppression and are optimized for a 20 dB or higher gain and radiation efficiency of ~90% at 60 GHz. The second research theme is implementing a 1 × 16-element beam steering antenna array with a low-cost piezoelectric transducer (PET) controlled phase shifter. A power divider with a triangular feed which reduces discontinuity from feed lines corners is introduced. A 1 × 16-element array is fabricated using 60 GHz AFTSA-SC antenna elements and showed symmetric E-plane and H-plane radiation patterns. The feed network design is surrounded by electromagnetic band-gap (EBG) structures to reduce surface waves and coupling between feed lines. The design of a circularly polarized 1 × 16-element beam steering phased array with and without EBG structures also investigated. A target detection investigation was carried out utilizing the proposed 60GHz antennas and their detection results are compared to those of V-band standard gain horn (SGH). System setup and signal pre-processing principle are introduced. The multi-corrugated MCAFTSA-SC probe is evaluated with the imaging/detection system for weapons and liquids concealed by clothing, plywood, and plastics. Results show that these items are detectable in clear 2D image resolution. It is believed that the 60 GHz imaging/detection system results using the developed probes show potential of detecting threatening objects through screening of materials and public

Low-Cost Integrated Waveguide Antenna Front-End Solutions for Fifth Generation Cellular Systems and Beyond

RÉSUMÉ : À ondes millimétriques (ou simplement mm - ondes) réseaux d'antennes avec un seul polarisation linéaire (LP ) , double polarisation linéaire ( DLP ) et double polarisation circulaire ( DCP) caractéristiques sont largement utilisés pour de nombreuses applications , il y compris la communication de données sans fil , capteurs radar , passive imagerie , la récupération d'énergie et les systèmes de radiocommunication cognitifs . Parmi les différents types de structure d'alimentation , guide d'ondes présente un excellent candidat pour mettre en oeuvre des réseaux d'alimentation à faible perte et gain élevé réseaux d'antennes sur la plage de fréquence à ondes millimétriques . Ces antennes à base de guide d'ondes - ont été présentant d'excellentes caractéristiques de rayonnement , mais ils ne sont pas faciles à intégrer avec des composants actifs . A la fréquence à ondes millimétriques , SIW ( substrat de guide d'ondes intégré ) est un candidat exceptionnel émergents à mettre en oeuvre une faible perte et des réseaux d'alimentation à faible coût. Antenne SIW - alimenté est capable de produire l'efficacité de rayonnement à haute et le comportement d'impédance à large bande . Dans cette thèse , la technologie de transmission alimentation SIW est choisi pour mettre en oeuvre des réseaux électriques et de phase de distribution pour réaliser une grande efficacité antenne extrémités avant. Les principales contributions scientifiques et techniques peuvent être résumées en deux parties .Dans la première partie , des solutions pour les ouvertures rayonnantes efficacement ont été proposés tels que gain élevé réseaux d'antennes LP , DLP réseaux d'antennes et DCP réseaux d'antennes . Le choix de l'élément rayonnant avec d'excellentes caractéristiques de rayonnement est vital dans la réalisation de gain élevé réseau d'antennes et réseaux phasés, électroniquement orientables . Dans la deuxième partie , de nouvelles techniques ont été proposées pour diriger le faisceau fixe dans des directions multiples en élévation et azimut en utilisant le réseau de décalage de phase passive.----------ABSTRACT Millimeter-wave (or simply mm-wave) antenna arrays with single linear polarization (LP), dual linear polarization (DLP) and dual circular polarization (DCP) characteristics are widely being used for numerous applications including wireless data communication, radar sensors, passive imaging, energy harvesting and cognitive radio systems. Among different types of feeding structure, waveguide presents an excellent candidate to implement low-loss feeding networks and high-gain antenna arrays over mm-wave frequency range. Those waveguide-based antennas have been exhibiting excellent radiation characteristics, but they are not easy to integrate with active components. At mm-wave frequency, SIW (substrate integrated waveguide) is an emerging outstanding candidate to implement low loss and low cost feeding networks. SIW-fed antenna is able to yield high radiation efficiency and broadband impedance behavior. In this thesis, SIW feeding transmission technology is chosen to implement power and phase distributing networks for realizing high efficiency antenna front ends. The main scientific and technical contributions can be summarized into two parts. In the first part, solutions for efficiently radiating apertures have been proposed such as high gain LP antenna arrays, DLP antenna arrays and DCP antenna arrays. The radiating element choice with excellent radiation characteristics is vital in realising high gain antenna array and electronically steerable phased arrays. In the second part, new techniques have been proposed to steer the fixed beam into multiple directions in elevation and azimuth utilizing passive phase shifting network. At 60 GHz frequency, dielectric rod antenna is selected for linearly polarized radiation and cavity backed metallic circular patch antenna is selected to obtain circular polarization radiation. Single rod antenna element is experimentally characterized to validate the proposed concept. In the next stage, high gain antenna array with 45o linear polarization utilizing rod antenna radiating element is demonstrated and feeding implemented in three dimensional (3-D) architecture is integrated along with the 4 x 4 antenna array. The data handling capability of single polarization antenna array is increased up to two fold by integrating two orthogonal polarized antenna arrays with an aperture area of one single polarized array

Hardware architectures for compact microwave and millimeter wave cameras

Millimeter wave SAR imaging has shown promise as an inspection tool for human skin for characterizing burns and skin cancers. However, the current state-of-the-art in microwave camera technology is not yet suited for developing a millimeter wave camera for human skin inspection. Consequently, the objective of this dissertation has been to build the necessary foundation of research to achieve such a millimeter wave camera. First, frequency uncertainty in signals generated by a practical microwave source, which is prone to drift in output frequency, was studied to determine its effect on SAR-generated images. A direct relationship was found between the level of image distortions caused by frequency uncertainty and the product of frequency uncertainty and distance between the imaging measurement grid and sample under test. The second investigation involved the development of a millimeter wave imaging system that forms the basic building block for a millimeter wave camera. The imaging system, composed of two system-on-chip transmitters and receivers and an antipodal Vivaldi-style antenna, operated in the 58-64 GHz frequency range and employed the ω-k SAR algorithm. Imaging tests on burnt pigskin showed its potential for imaging and characterizing flaws in skin. The final investigation involved the development of a new microwave imaging methodology, named Chaotic Excitation Synthetic Aperture Radar (CESAR), for designing microwave and millimeter wave cameras at a fraction of the size and hardware complexity of previous systems. CESAR is based on transmitting and receiving from all antennas in a planar array simultaneously. A small microwave camera operating in the 23-25 GHz frequency was designed and fabricated based on CESAR. Imaging results with the camera showed it was capable of basic feature detection for various applications --Abstract, page iv

Mode Composite Waveguide for 5G and Future Wireless Communication Systems

RÉSUMÉ Dans les systèmes de communication sans fil modernes, les fonctionnalités haut-débit et multi-bande des circuits RF et micro-ondes sont de plus en plus requises dans des systèmes intégrés et compacts. La bande de fréquence actuellement utilisée pour les communications sans fil commerciales comprend les bandes aux alentours de 900 MHz, 1,9 GHz, 2,45 GHz, 3,5 GHz et 5,8 GHz pour la téléphonie mobile, l'Internet sans fil et la connectivité des capteurs. Les nouvelles bandes millimétriques comme la bande de fréquence V (57-66 GHz) et la bande E (71-76 GHz et 81-86 GHz) sont utilisées pour la connectivité des microcellules et du coeur du réseau. Le nouveau standard des communications sans fils 5G nécessite l’exploitation parallèle de bandes de fréquences, à savoir les basses et les hautes fréquences, permettant ainsi d’aller au-delà de la capacité des systèmes de communications actuels. D’une part, la demande croissante pour un meilleur débit de données nécessite une bande de fréquence beaucoup plus large, ce qui justifie le recours vers la bande de fréquences millimétriques. D'autre part, le standard LTE ainsi que les autres systèmes de communication à grande couverture doivent être développés de manière compatible avec les bandes de fréquences en bas de 6 GHz et celles qui sont au-delà de 6 GHz. Par conséquent, la mise au point de nouveaux systèmes intégrés et à bas coût capables d’opérer sur fréquences UHF et millimétriques s’avère essentielle pour le standard sans fil émergent (5G). Dans cette thèse, une nouvelle méthode de conception de circuits intégrés RF large bande et multi-bande, appelée guide d'ondes à modes composites (MCW), est proposée et étudiée. Le MCW est constitué d’une structure à double guide d'ondes interne et externe, où la structure externe agit comme une ligne coaxiale rectangulaire adaptée pour les basses fréquences, tandis que la structure interne fonctionne comme un guide d'onde rectangulaire pour les hautes fréquences, ce qui rend la structure plus simple, plus compacte et à faibles pertes d’insertion. Le MCW est susceptible de propager des signaux au sein du guide d'ondes interne suivant le mode TE10 et/ou au sein du guide d'onde externe avec le mode TEM en fonction de la fréquence, permettant ainsi d’aboutir à des performances optimales pour les deux bandes de fréquences (basse et haute). Pour ce faire, les paramètres fondamentaux du guide d'ondes et les modes d'ordre supérieur du MCW sont théoriquement étudiés.----------ABSTRACT In modern wireless communication systems, broadband and multiband functionalities of RF and microwave circuits are often required in a highly integrated and geometrically compact front-end systems. The currently used frequency band for commercial wireless communication includes the lower bands of 900 MHz, 1.9 GHz, 2.45 GHz, 3.5 GHz and 5.8 GHz for mobile phone, wireless internet and sensor connectivity, as well as the emerging millimeter-wave (mmW) bands of V-band (57-66 GHz) and E-band (71-76 GHz and 81-86 GHz) for small cell and backhaul connectivity. The emerging 5G wireless communication system requires the deployment of both low- and high-dual frequency bands in a simultaneous manner, which should extend far beyond the capability of existing mobile communication systems. On one hand, the increasing demand for higher speed wireless data transmission requires a much larger bandwidth, where the mmW bands shall be exploited to accommodate such a bandwidth increase. On the other hand, the LTE and other long-ranged wireless platforms need to be developed in a backwards-compatible way, and it is also very important to accommodate the frequency bands below 6 GHz or sub-6-GHz frequency ranges. Therefore, the development of a low-cost and integrated hardware solution is essential for the 5G and future wireless communication systems, which should be able to support the emerging wireless deployments over an unprecedented wide UHF-to-mmW frequency range. In this thesis, the development of a broadband or multi-band hardware design platform or building technology, called mode composite waveguide (MCW), is proposed and addressed. The MCW consists of inner and outer wave-guiding duo structures, where the outer structure acts as a rectangular coaxial line suitable for lower frequency operation for its compact size, while the inner structure works as a rectangular waveguide suitable for higher frequency operation thanks to its simple structure and low loss. The MCW can propagate signals in the inner waveguide with TE10 mode and/or the outer waveguide with TEM mode depending on frequency to achieve optimal performance for both low and high frequency operations

Design and analysis of wideband passive microwave devices using planar structures

A selected volume of work consisting of 84 published journal papers is presented to demonstrate the contributions made by the author in the last seven years of his work at the University of Queensland in the area of Microwave Engineering. The over-arching theme in the author’s works included in this volume is the engineering of novel passive microwave devices that are key components in the building of any microwave system. The author’s contribution covers innovative designs, design methods and analyses for the following key devices and associated systems: Wideband antennas and associated systems Band-notched and multiband antennas Directional couplers and associated systems Power dividers and associated systems Microwave filters Phase shifters Much of the motivation for the work arose from the desire to contribute to the engineering o

Fast Methods for Millimeter-wave Dielectric Resonator and Antenna Analysis and Design

Ever-increasing interest in millimeter-wave and terahertz spectrum has prompted research and development of novel passive components working at these frequencies. Compared with the conventional planar components, non-planar dielectric devices become more attractive as frequencies increase due to their higher quality factors and dimensional tolerances. In this thesis, we present fast methods to analyze the millimeter-wave dielectric resonator and rod antenna. First, an analytical method has been developed to evaluate resonant frequencies, quality factors of the Whispering Gallery Mode (WGM) disk resonators and also the resonator-waveguide coupling. A numerical solver based on full-wave finite element method is implemented to verify the analytical result. This analytical model provides a solution for fast design and optimization of WGM resonators in filter and sensor applications. Secondly, a fast analytical approach based on local mode theory is introduced to calculate the radiation from tapered dielectric rod antenna. This efficient approximate model consumes much less computing resources and time, and demonstrates good agreements with full-wave numerical results. It supplies a quantitative way to understand the radiation mechanism and interaction between different parts of the antenna. Based on this, design criteria for the taper profile of rod antennas are given