Microwave Slow-Wave Structure and Phase-Compensation Technique for Microwave Power Divider

In this paper, T-shaped electromagnetic bandgap is loaded on a coupled transmission line itself and its electric performance is studied. Results show that microwave slow-wave effect can be enhanced and therefore, size reduction of a transmission-line-based circuit is possible. However, the transmission-line-based circuits characterize varied phase responses against frequency, which becomes a disadvantage where constant phase response is required. Consequently, a phase-compensation technique is further presented and studied. For demonstration purpose, an 8-way coupled-line power divider with 22.5 degree phase shifts between adjacent output ports, based on the studied slow-wave structure and phase-compensation technique, is developed. Results show both compact circuit architecture and improved phase imbalance are realized, confirming the investigated circuit structures and analyzing methodologies

Ultrawideband and Multi-state Reconfigurable Antennas with Sum and Difference Radiation Patterns

Pattern diversity is a term used to describe the operation of several antenna elements working together to produce multiple different radiation patterns with the aim of improving the quality and reliability of a communications system. One useful implementation of pattern diversity considers sum and difference radiation patterns which can be exploited to extend high-gain space coverage and tackle multipath fading. The conventional forms of such pattern diversity antennas are generally working at a single or multiple narrowband frequencies and are designed for specific applications. Hence, generating sum and difference pattern diversity in wide range of frequencies requires the development of new pattern diversity antenna designs. Ultrawideband and frequency reconfigurable designs of pattern diversity antennas are desirable to help reduce the cost and increase the flexibility in applications of pattern diversity antennas. These two types of performances constitute the principal parts of this thesis. The first part of this thesis deals with the challenges of designing ultrawideband Vivaldi antennas with sum and difference radiation patterns. When two Vivaldi antennas are placed next to each other, two mutually exclusive phenomena of grating lobe generation at the highest end of frequency and mutual coupling at the lowest end of frequency will define the bandwidth. Hence, to enhance the bandwidth, the separation between the antenna elements is reduced, which delays the grating lobes generation, and the coupling at lower frequencies is mitigated by introducing an asymmetry in the design of each Vivaldi antenna element. It is shown that this method can be extended to multi-element Vivaldi antennas for higher gain. Next, the bandwidth is further enhanced by adding two vertical metal slabs between the antenna elements improving the isolation at lower frequencies. The proposed antennas use commercially available couplers as feeding networks. As a potential replacement for couplers, an out-of-phase power divider with unequal power division is also proposed. In the second part of this thesis, the pattern diversity function is combined with multistate frequency-reconfigurable filtering functions in a series of novel designs. In the first proposed design, two quasi-Yagi-Uda antennas are used for pattern diversity, while two switchable and reconfigurable bandpass-to-bandstop filters are used to excite the antenna elements. The whole system is excited by an external commercially available rat-race coupler. In a next step, this design is modified to attain wideband, tunable bandpass, and tunable bandstop operations while obviating the need for an external coupler by using three antenna elements excited by a switchable power divider. In another implementation, the filtering functions is extended to dual-band independently tunable bandpass and bandstop to excite wideband antennas. While all the former designs featured E-plane pattern diversity, in another design aiming at increasing space coverage, a switchable patch antennas with sum and difference radiation patterns in both E- and H-plane of the antenna is designed.Thesis (Ph.D.) -- University of Adelaide, School of Electrical and Electronic Engineering, 202

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

Analytical Design Procedures for the Odd Mode of Ridge Gap Waveguide Devices and Antennas

The millimeter-wave (mm-wave) band has attracted attention due to its wideband characteristics that make it able to support multi-gigabit per second data rate. Nevertheless, the performance of mm-wave wireless communication systems is restricted due to attenuation loss. Design of mm-wave components and antennas is rapidly growing with the current evolution in the wireless communication systems. However, the traditional waveguide structures such as microstrip, coplanar, substrate integrated waveguide, and rectangular waveguide either suffer from high losses or difficulty in manufacturing at mm-wave band. The ridge gap waveguide (RGW) technology is considered as a promising waveguide technology for the mm-wave band. RGW technology overcomes the conventional guiding structure problems as the wave propagates in an air gap region which eliminates the dielectric loss. Moreover, RGW does not need any electrical contacts, unlike traditional rectangular waveguides. Also, the RGW can be implemented in the printed form (PRGW) for easy integration with other planer system components. In this thesis, the use of the odd mode (TE10 (RGW)) RGW to design mm-wave components and antennas is presented. First, a systematic design methodology for the RGW using hybrid PEC/PMC waveguide approximation is presented. This reduces the design time using full wave simulators. The concept has been verified by simulation and experimental measurements. Second, two different methods to excite the odd mode in RGW are studied and investigated. In the first method, a planar L-shape RGW is used where less than -10 dB reflection coefficient is achieved, from 28 to 36 GHz, and more than 93% of the input power has been converted into the odd mode at the output port. The second method uses a magic tee with a shorted sum port and provides a wideband pure odd mode at the output port with reflection coefficient less than -10 dB from 28 GHz to 39 GHz. Other mm-wave components based on odd mode TE10 RGW are designed and presented including a Y-junction power divider and 3 dB forward coupler are designed for the first time in RGW technology. The Y-junction has a wideband matching from 28 to 34 GHz with a reflection coefficient less than -15 dB and the transmission output levels are about -3.3 dB. The usefulness of the odd mode RGW lies in the ability to increase the channel bandwidth that has been achieved by designing a dual-mode RGW. A magic tee is used to simultaneously excite the fundamental mode Q-TEM and the odd mode TE10 (RGW) on the ridgeline. The proposed dual-mode RGW performance is verified through simulation and measurement of a back-to-back configuration. The proposed design achieves a matching level less than -10 dB for the two modes over the frequency range from 29 GHz to 34.5 GHz with isolation better than 23 dB. The dual-mode RGW is then used to feed a reconfigurable Vivaldi horn antenna where two different radiation patterns can be obtained depending on the excited mode. The Q-TEM generates a single beam pattern, while the odd mode TE10 (RGW) generates a dual-beam pattern. The maximum gain for the single beam radiation is 12.1 dBi, while it is 10.43 dBi for the dual-beam pattern. The bandwidth of the dual-mode antenna is 25% at 32 GHz with impedance matching less than -10 dB and isolation better than 20 dB. Finally, several antennas are presented in this thesis based on the odd mode RGW. A novel differential feeding cavity antenna using the odd mode of RGW is presented. The measured results show good performance in terms of gain, bandwidth, sidelobe level, and cross-polarization. The maximum gain is 16.5 dBi, and the sidelobe level is -17 dB and -13.8 dB, for the E-plane and H-plane, respectively. Moreover, the proposed antenna has low cross-polarization levels of -35 dB in the E-plane and -27 dB in the H-plane. In addition, two 2x1 linear frequency scanning array antennas are designed and implemented using the proposed Y-junction to generate single beam and dual-beam patterns. The beam scan is from -11(degree) to -40(degree) at 28 GHz and 32 GHz, respectively

Étude et réalisation de matrices à commutation de faisceaux en technologie guide d'ondes intégré au substrat

RÉSUMÉ Les applications radar pour les voitures demandent des composants de hautes performances mais avec faible coût de revient. Cette thèse présente la conception des réseaux d’alimentation d’antennes en ondes millimétriques utilisant la technologie du guide d’ondes intégré aux substrats (GIS), pour satisfaire les exigences du coût et du faible encombrement dans ces applications de radar. Dans un système radar, l’antenne défini la largeur du secteur couvert, la portée, la discrimination angulaire et le filtrage du bruit généré par d’autre sources. Généralement les antennes intelligentes remplissent ce cahier des charges. La direction dans laquelle le réseau ayant la réponse maximale serait la direction du pointage de faisceau. Pour un choix de faisceau dans une direction désirée, un ajustement de phase doit être accompli. Les matrices à commutation donnent des distributions de phase aux sorties différentes pour chaque port d’entrée. Le guide d’ondes intégré aux substrats (GIS) offre une technologie intéressante pour les réseaux d’alimentation d’antennes en termes de faible pertes par radiation, ce qui assure un très faible niveau d’interférences et d’effets parasitiques entre les circuits de GIS. Nous proposons dans ce travail plusieurs matrices de formation de faisceaux basées sur la technologie GIS. La thèse est présentée sous forme d’articles. Ce travail montre les étapes entreprises afin de mener à terme la conception, la fabrication, les mesures et l’évaluation de plusieurs topologies de la matrice de Butler. Nous verrons donc dans un premier temps les composants nécessaires au bon fonctionnement d’un tel système soit: les coupleurs 3 dB, les déphaseurs et les croisements. Le choix de la configuration sera justifié pour chacun de ces éléments. L’usage de simulateur (Ansoft HFSS) basé sur la méthode des éléments finis (une méthode à ondes complètes) sera nécessaire dans ce travail. Ce logiciel donne des résultats assez proches des essais expérimentaux. Trois matrices de Butler sont développées, la première à 77 GHz sans croisement, une deuxième est une structure à deux couches à 24 GHz et la troisième est une matrice complètement planaire avec un coupler 0 dB à 12.5 GHz.---------- ABSTRACT Automotive radar applications require components with high performance but low cost. This thesis presents the design of millimeter wave antennas feeding networks using the substrate integrated waveguide (SIW) technology, to satisfy the requirement of low cost and compactness in these radar applications.In a radar system the antenna define the width of covered area, the range, the angular discrimination and the filter noise generated by other sources. Generally smart antennas must be used to satisfy the specifications. The beam pointing can be achieved only by adjusting the phase of signals from different elements. For a choice of beam in a desired direction, a phase adjustment must be done. Switching matrices are used to provide phase distribution at output ports that is different for each input port. The substrates integrated waveguide (SIW) is a promising technology for the antenna feed networks in terms of low radiation and transmission losses with reduced interferences among SIW circuit elements. We propose in this work several beamforming matrices based on SIW technology. This thesis is presented in paper form. First of all, this work shows the steps taken to finalize the design, fabricate, measurement and evaluation of several Butler matrix topologies. We will see at first that the building components necessary for the proper functioning of such a network: the 3 dB couplers, phase shifters and crossovers. The choice of a configuration will be justified for each of these elements. An electromagnetic simulator (Ansoft HFSS) based on the finite element method (full-wave method) is used in this work. This software package would be able to yield results close to experimental counterparts. Three Butler matrices are developed, the first at 77GHz without crossover, the second is related to a two layer structure at 24 GHz and the third is completely made planar with a cross-over at 12.5 GHz. The Nolen matrix compared to Butler matrix has the advantages of being free from crossovers in the structure. The loads placed on unused ports in the Blass matrix do not appear in the Nolen matrix which increases efficiency. We propose two architectures, the first one is related to perpendicular configuration in Ku band while the second platform presents a parallel topology which shows a good performance over a broad band around 77 GHz

Millimeter-Wave Components and Antennas for Spatial and Polarization Diversity using PRGW Technology

The evolution of the wireless communication systems to the future generation is accompanied by a huge improvement in the system performance through providing a high data rate with low latency. These systems require access to millimeter wave (mmWave) bands, which offer several advantages such as physically smaller components and much wider bandwidthcomparedtomicrowavefrequencies. However, mmWavecomponentsstillneed a significant improvement to follow the rapid variations in future technologies. Although mmWave frequencies can carry more data, they are limited in terms of their penetration capabilities and their coverage range. Moreover, these frequencies avoid deploying traditional guiding technologies such as microstrip lines due to high radiation and material losses. Hence, utilizing new guiding structure techniques such as Printed Ridge Gap Waveguide (PRGW) is essential in future mmWave systems implementation. ThemainpurposeofthisthesisistodesignmmWavecomponents,antennasubsystems and utilize both in beam switching systems. The major mmWave components addressed in this thesis are hybrid coupler, crossover, and differential power divider where the host guidingstructureisthePRGW.Inaddition,variousdesignsfordifferentialfeedingPRGW antennas and antenna arrays are presented featuring wide bandwidth and high gain in mmWave band. Moreover, the integration of both the proposed components and the featured antennas is introduced. This can be considered as a significant step toward the requirements fulfillment of today's advanced communication systems enabling both space and polarization diversity. The proposed components are designed to meet the future ever-increasing consumer experience and technical requirements such as low loss, compact size, and low-cost fabrication. This directed the presented research to have a contribution into three major parts. The first part highlights the feeding structures, where mmWave PRGW directional couplers and differential feeding power divider are designed and validated. These components are among the most important passive elements of microwave circuits used in antennabeam-switchingnetworks. Different3-dBquadraturehybridcouplersandcrossover prototypes are proposed, featured with a compact size and a wide bandwidth beyond 10 % at 30 GHz. In the second part, a beam switching network implemented using hybrid couplers is presented. The proposed beam switching network is a 4 × 4 PRGW Butler matrix that used to feed a Magneto-electric (ME) dipole antenna array. As a result, a 2-D scanning antenna array with a compact size, wide bandwidth, and high radiation efficiency larger than84%isachieved. Furthergainenhancementof5dBiisachievedthroughdeployinga hybridgainenhancementtechniqueincludingAMCmushroomshapesaroundtheantenna array with a dielectric superstrate located in the broadside direction. The proposed scanning antenna array can be considered as a step toward the desired improvement in the data rate and coverage through enabling the space diversity for the communication link. The final activity is related to the development of high-gain wide-band mmWave antenna arrays for potential use in future mmWave applications. The first proposed configuration is a differential feeding circular polarized aperture antenna array implemented with PRGW technology. Differential feeding antenna designs offer more advantages than single- ended antennas for mmWave communications as they are easy to be integrated with differential mmWave monolithic ICs that have high common-mode rejection ratio providing an immunity of the environmental noise. The proposed differential feeding antenna array is designed and fabricated, which featured with a stable high gain and a high radiation efficiency over a wide bandwidth. Another proposed configuration is a dualpolarized ME-dipole PRGW antenna array for mmWave wireless communication. Dual polarizationisconsideredoneofthemostimportantantennasolutionsthatcansavecosts and space for modern communication systems. In addition, it is an effective strategy for multiple-input and multiple-output systems that can reduce the size of multiple antennas systems by utilizing extra orthogonal polarization. The proposed dual- polarized antenna array is designed to achieve a stable gain of 15 ± 1 dBi with low cross- polarization less than -30 dB over a wide frequency range of 20 % at 30 GHz

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

Microwave and Millimeter-wave Miniaturization Techniques, and Their Applications

Miniaturization is an inevitable requirement for modern microwave and mm-wave circuits and systems. With the emerging of high frequency monolithic integrated circuits, it is the passive components’ section that usually occupies the most of the area. As a result, developing creative miniaturization techniques in order to reduce the physical sizes of passive components while keep their high performance characteristics is demanding. On the other hand, it is the application that defines the importance and effectiveness of the miniaturization method. For example, in commercial handset wireless communication systems, it is the portability that primarily dictates miniaturization. However, in case of liquid sensing applications, the required volume of the sample, cost, or other parameters might impose size limitations. In this thesis, various microwave and mm-wave miniaturization methods are introduced. The methods are applied to various passive components and blocks in different applications to better study their effectiveness. Both componentlevel designs and system-level hybrid integration are benefited from the miniaturization methods introduced in this thesis. The proposed methods are also experimentally tested, and the results show promising potential for the proposed methods