Inkjet Printed Flexible Patch Antennas for Full Duplex and Circular Polarization Applications

Flexible devices are getting more popular nowadays because of it’s lightweight, small size, portability, less expensive, environment friendly, and disposability. Flexible antenna, part of flexible devices, has become an important component of research for electrical engineers. The flexible antenna can be built using different materials like PET, PEN, liquid crystal polymer, PDMS, and textiles like woolen felt, cotton, cordura, and fleece as substrate. This thesis focuses on designing and fabricating antennas on PET paper by using inkjet printing for full duplex and circular polarization applications. Firstly, a flexible full-duplex antenna is proposed with robust performance and high isolation for 5.8 GHz using foam and PET paper. The patch of the antenna is modified by corner cut and inset feeding, while the defected ground structure is used to improve isolation between transmit and receive ports. Silver nanoparticle ink is used for printing the antenna in an inkjet printer. The fabricated version supports simulated results by showing acceptable performance in desired bandwidth. Bending tests and human body loading experiments are carried out on the fabricated antenna to demonstrate the antenna’s effectiveness for wearable applications. To the best of author’s knowledge, this is the first flexible full duplex antenna designed, achieving a high isolation level of -50 dB. Moreover, wide bandwidth, improved gain, and radiation efficiency, low cost, easy fabrication, and robust performance make it a good option for 5.8 GHz wearable applications. Secondly, a simple and compact CPW-fed circularly polarized antenna is presented. The proposed antenna consists of a modified “S” shaped patch, which has slots in three different places along with a slot in the ground plane. These slots contribute to increasing the bandwidth of the axial ratio. The antenna has a 3 dB axial ratio bandwidth of 10.47% (4.07 GHz- 4.52 GHz) and an impedance bandwidth of 17.53% (3.8 GHz - 4.53 GHz) covering the full region of axial ratio band. Moreover, this antenna is designed using PET paper which makes it flexible in nature and the first flexible antenna in the discussed frequency range to the best of author’s knowledge. Finally, an inkjet printed circularly polarized antenna using CPW feeding on PET substrate is proposed. The antenna is designed and optimized using ANSYS HFSS, which operates at 4.01 GHz - 5.05 GHz and 6.23 GHz - 7.58 GHz with a return loss of < -10 dB. On top of that, the antenna shows an axial ratio of less than 3 dB at 4.23 GHz - 4.62 GHz and 7.11 GHz - 7.36 GHz, whereas left hand circular polarization (LHCP) is observed in the first band and right hand circular polarization (RHCP) is observed in the second band. The dimension of the antenna is 31 mm x 37 mm x 0.135 mm. Measurement of the fabricated version shows good agreement with the simulated version. To the best of author’s knowledge, this antenna is the first flexible CPW-fed circularly polarized antenna with dual band

Innovative Microwave and Millimetre-Wave Components and Sub-Systems Based on Substrate Integration Technology

RÉSUMÉ Avec le rapide développement des technologies microondes et millimétriques, les spécifications de conception des circuits et systèmes sont de plus en plus exigeantes. La tendance pour le développement des systèmes de communication se dirige vers un poids minimisé, une taille réduite, de multiples fonctions, une fiabilité accrue et un faible coût. Ainsi, des technologies microondes et millimétriques faibles coûts, performantes et convenant à une production de masse sont critiques pour développer avec succès des systèmes commerciaux. La technologie à guide d’ondes rectangulaire a toujours été parmi les plus populaires pour la fabrication des systèmes millimétriques. Cependant, une difficulté majeure est reliée à leur intégration avec des composants actifs et les autres types de lignes de transmission conventionnelles, telle que microruban ou coplanaire… Les technologies de Circuits Intégrés au Substrat (CISs), incluant la technologie Guide Intégré au Substrat (GIS), qui peut être intégrée dans les substrats diélectriques avec de faibles pertes d’insertion et de radiation, sont une famille de nouvelles structures à ondes guidées. Ces dernières permettent de faire un pont entre les structures planaires et non-planaires. Jusqu’à maintenant, les composants et les sous-systèmes micro-ondes basés sur la technologie GIS ont été largement étudiés et développés. Dans cette thèse, nous étudions d’avantage la technologie GIS afin de proposer et développer divers composants actif et passif micro-ondes et millimétriques innovant et originaux. Ces structures de composants innovants peuvent améliorer l’intégration entre les composants GIS et les autres composants planaires. Ainsi, un certain nombre de structures et composants sont proposés et appliqués dans la conception et la démonstration d’un réseau d’antennes intégré en ondes millimétriques et un sous-système d’antennes intelligentes à 60 GHz. Il est à noter que plusieurs composants étudiés dans ce travail ont été proposés et démontrés à des fréquences micro-ondes plus basses afin de faire une preuve de concept en permettant une fabrication facile des structures et des circuits. Ces circuits en basses fréquences peuvent facilement être adaptés pour des applications aux fréquences plus hautes.---------- ABSTRACT The tendency of modern microwave and millimetre-wave communication system development is towards small size, light weight, reliable, multifunctional and low-cost. Moreover, low-cost, mass producible, high-performance and high-yield microwave and millimetre wave technologies are crucial for developing successful commercial microwave and millimetre wave systems. Rectangular waveguide has always been among the most popular choices for the making of millimetre-wave circuits and systems. A major challenge, however, is related to its integration with active devices and other conventional planar transmission lines, such as microstrip or coplanar waveguide (CPW), etc. Substrate Integrated Circuits (SICs) techniques including substrate integrated waveguide (SIW), which can be integrated in planar dielectric substrate with low insertion loss, high Q and low radiation loss, present a family of novel guided wave structures. This scheme provides a bridge between planar and non-planar structures. Up to now, microwave components and sub-systems based on SIW technology have been widely studied and developed. In this thesis, we take a further study of SIW technology to propose and develop various innovative and original microwave and millimetre-wave passive and active components. These innovative component structures can improve the integration between SIW components and other planar components. Then, a certain number of proposed structures or components are applied in the design and demonstration of millimetre-wave integrated antenna arrays and 60 GHz smart antenna sub-system. Note that many components studied in this work were proposed and demonstrated at different lower microwave frequencies for the proof of concept purpose with easy-to-fabricate structures and circuits. Those low-frequency circuits can easily be scaled up for high-frequency applications

A Survey of Differential-Fed Microstrip Bandpass Filters: Recent Techniques and Challenges

Differentially driven devices represent a highly promising research field for radio frequency (RF), microwave (MW), and millimeter-wave (mmWave) designers and engineers. Designs employing differential signals are essential elements in low-noise fourth-generation (4G) and fifth-generation (5G) communications. Apart from the conventional planar MW components, differential–fed balanced microstrip filters, as promising alternatives, have several advantages, including high common-mode rejection, low unwanted radiation levels, high noise immunity, and wideband harmonic suppression. In this paper, a comprehensive and in-depth review of the existing research on differential-fed microstrip filter designs are presented and discussed with a focus on recent advances in this research and the challenges facing the researchers. A comparison between different design techniques is presented and discussed in detail to provide the researchers with the advantages and disadvantages of each technique that could be of interest to a specific application. Challenges and future developments of balanced microstrip bandpass filters (BPFs) are also presented in this paper. Balanced filters surveyed include recent single-, dual-, tri-, and wide-band BPFs, which employ different design techniques and accomplish different performances for current and future wireless applications

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

Advances in Reconfigurable Antenna Systems Facilitated by Innovative Technologies

© 2013 IEEE. Future fifth generation (5G) wireless platforms will require reconfigurable antenna systems to meet their performance requirements in compact, light-weight, and cost-effective packages. Recent advances in reconfigurable radiating and receiving structures have been enabled by a variety of innovative technology solutions. Examples of reconfigurable partially reflective surface antennas, reconfigurable filtennas, reconfigurable Huygens dipole antennas, and reconfigurable feeding network-enabled antennas are presented and discussed. They represent novel classes of frequency, pattern, polarization, and beam-direction reconfigurable systems realized by the innovative combinations of radiating structures and circuit components

High Gain Broadband mm-Wave Antenna Arrays for Short-range Wireless Communication Systems

Recently, the ever-increasing demand for fifth-generation (5G) wireless applications has turned millimeter-wave (mm-wave) multi-beam array antenna into quite a promising research direction. Besides offering a remarkable bandwidth for high-speed wireless connectivity, the short wavelengths (1 to 10 mm) of mm-wave signals makes the size of the antenna array with beamforming network (BFN) compatible with a transceiver front-end. The high losses associated with mm-wave wireless links and systems considered the foremost challenge and may restrict the wireless communication range. Therefore, a wideband substrate integrated waveguide (SIW)-based antenna with high gain and beam scanning capabilities would be a solution for these challenges, as it can increase the coverage area of mm-wave wireless systems and mitigate the multipath interference to achieve a high signal to noise (S/N) ratio, and thereby fulfill the link budget requirements. This thesis focuses on the analysis and design of single- and multi-beam mm-wave antenna arrays based on SIW technology to fulfill the growing demand for wideband high-gain planar antenna arrays with beam steering capability at V-band. A tapered slot antenna (TSA) and cavity-backed patch antenna are used as the main radiators in these systems to achieve high-gain and high efficiency over a wide range of operating frequencies. Accordingly, numerous design challenges and BFN-related issues have been addressed in this work. Firstly, an antipodal Fermi tapered slot antenna (AFTSA) with sine-shaped corrugations is proposed at V-band. The antenna provides a flat measured gain of 20 dB with a return loss better than 22 dB. In addition, A broadband double-layer SIW-to-slotline transition is proposed to feed a planar linearly tapered slot antenna (PLTSA) covering the band 46-72 GHz. This new feeding technique, which addresses the bandwidth limits of regular microstrip-to-slotline transitions and avoids the bond wires and air bridges, is utilized to feed a 1x4 SIW-based PLTSA array. Secondly, a new cavity-backed aperture-coupled patch antenna with overlapped 1-dB gain and impedance bandwidth of 43.4 % (56-87 GHz) for |S11| < -10 dB and an average gain of 8.2 dBi is designed. A detailed operating principle is presented. Based on the proposed element, an SIW based 1x8 array is constructed, whose beam-shape is synthesized by amplitude tapering according to Taylor distribution to reduce the sidelobe level. Moreover, a four-layered 4x4 cavity-backed antenna array with a low-loss full-corporate SIW feed network is implemented for gain and aperture efficiency enhancement. The measured results exhibited a bandwidth of 38.4 % (55.2-81.4 GHz) for |S11| < -10 dB and a gain of 20.5 dBi. A single-layer right-angle transition between SIW and air-filled WR15 waveguide along with an equivalent circuit model is introduced and used to measure the performance of both proposed linear and planar arrays. Thirdly, two 1-D scanning multi-beam array designs based on SIW technology, at 60 GHz, have been presented. The first design is a compact multi-beam scanning 4x4 slot antenna array with broadside radiation. The BFN is implemented using a dual-layer 4x4 Butler matrix, where the 450 and 00 phase shifters are designed on a separate layer with different permittivity, resulting in a significant size reduction compared to a conventional single layer. A detailed theoretical analysis, principle of operation and the circuit-model of the proposed phase shifter have been discussed, showing less desperation characteristics compared to ordinary phase shifters. The measured results show an azimuthal coverage of 1210. The second design is a wideband high gain multi-beam tapered slot antenna array with end-fire radiation. An SIW Butler matrix with a modified hybrid crossover is used as a BFN. The fabricated prototype exhibits a field of view of 970 in the azimuthal plane, with measured gain ranges from 12.7 to 15.6 dBi. Lastly, a novel three-layered SIW-fed cavity-backed linearly polarized (LP) patch antenna element is presented, covering a bandwidth of 36.2 % (53-76.4 GHz) with a flat gain ranging from 7.6 to 8.2 dBi. A compact two-layered beam forming network is designed with a size reduction of 28 % compared to a standard one-layered BFN without affecting its s-parameters. The results show that the impedance bandwidth is 31.1 % (51.5-70.5 GHz) for |S11|<-16 dB with an average insertion loss of 1.3 dB. The proposed antenna element and BFN are employed to form a compact 2x2 multibeam array at 60 GHz for 2-D scanning applications. The array shows a bandwidth better than 27 % with a radiation gain of up to 12.4 dBi and radiation efficiency of 80%. The multi-beam array features four tilted beams at 330 from a boresight direction with 450, 1350, 2250 and 3150 in azimuth directions, i.e., on e beam in each quadrant

The Complementary Strip-Slot: Analysis and Antenna Applications

Aunque el diseño de la antena en un sistema de comunicaciones pueda parecer un problema clásico, los servicios que han aparecido recientemente requieren nuevas funcionalidades, mayores anchos de banda, mejor eficiencia y directividad, así como bajo coste en la fabricación. Las antenas planares han sido unas de las más usadas y estudiadas en las últimas décadas y unas de las mejores candidatas para los nuevos servicios de telecomunicación. Sus ventajas son claras: poco peso, bajo coste y perfil, compatibilidad con la circuitería integrada, pequeño tamaño y reducido coste de fabricación. Sin embargo, su éxito se ha visto limitado por el escaso ancho de banda que presentan. Debido a la naturaleza resonante de la ranura y el parche alimentados por microstrip, sus anchos de banda en impedancia son insuficientes para la mayoría de los servicios de comunicaciones actuales. La mejora de este parámetro ha sido objeto de numerosas investigaciones; sin embargo, este problema sigue sin estar resuelto definitivamente y constituye una línea importante de investigación en antenas planares. Otra limitación de las antenas microstrip es la baja eficiencia de radiación comparada con otras antenas, que se supera combinando varios elementos para formar arrays. Una posibilidad para excitar el array es la alimentación en serie, que tiene las ventajas de simplicidad, menor espacio sobre el sustrato, pérdidas de atenuación más bajas y menor radiación espúrea, comparada con la alimentación corporativa. En esta tesis doctoral se ha propuesto un nuevo elemento radiante, el denominado strip-slot complementario, cuya principal característica es la eliminación de la naturaleza resonante de la antena de ranura excitada a través de línea microstrip por medio de introducir una strip (tira conductora) superpuesta a la ranura y en la cara de la microstrip. Con esta sencilla modificación, se crea una sección acoplada que puede diseñarse para presentar un comportamiento paso-todo. Las principales ventajas de la estructura son su simplicidad, que posee un único sustrato y que no necesita vías, lo que se traduce en bajo coste. Además, su alimentación en serie la hace muy apropiada para construir arrays de onda progresiva. Se ha analizado el comportamiento electromagnético de esta estructura y se ha obtenido un circuito equivalente basado en red en celosía que no sólo explica sus propiedades, sino que permite, además, establecer una eficaz metodología de diseño. Cabe destacar el trabajo relacionado con las redes en celosía. Se ha extraído una propiedad relevante sobre la independencia de las potencias disipadas en esta topología de circuito, que ha permitido explicar por qué la strip no altera las propiedades radiantes de la ranura. Además, esta red circuital se ha propuesto de una forma más general para el modelado de discontinuidades y componentes de LT simétricos, con la ventaja de garantizar la realizabilidad física de sus componentes, a diferencia de las ampliamente usadas redes en T o en π. Una vez caracterizado el elemento radiante propuesto, se ha ilustrado su potencial con una serie de novedosos diseños de arrays de antenas que se benefician de su elevado ancho de banda para proporcionar nuevas funcionalidades. En primer lugar, se estudia el concepto de array más inmediato, que consiste en cargar la línea microstrip con varios elementos strip-slot idénticos. Con un sencillo prototipo, se demuestra la capacidad de escaneo en frecuencia de atrás hacia delante del array (incluyendo broadside) en dos bandas distintas. Además, se diseña y construye un prototipo más sofisticado, que incluye desfasadores entre los elementos, con el objetivo de controlar el ángulo de apuntamiento de forma electrónica, sobre una banda ancha de frecuencias, sin necesidad de modificar la geometría del elemento radiante gracias a su gran ancho de banda. Esta antena representa una contribución importante a las propuestas del estado del arte. A continuación, se estudia el concepto de un array log-periódico basado en el elemento strip-slot, a través de un diseño y su correspondiente prototipo. Para ello, es necesario adaptar la metodología de diseño, concebida para elementos resonantes, y trasladarla al caso de elementos de banda ancha. La reconsideración de dicha metodología puede ser una aportación significativa, puesto que indica la posibilidad de reducción de tamaño (o anchos de banda mayores) cuando se utilizan elementos no-resonantes. Finalmente, se aborda el diseño de un array que implementa la técnica de rotación secuencial con los elementos strip-slot para proporcionar agilidad en polarización. Además, como aplicación del concepto, se incluye la propuesta de una novedosa antena con capacidad diplexora para la recepción simultánea de dos bandas de navegación por satélite, que no requiere de elementos pasivos o activos adicionales. Puesto que se ha presentado una nueva clase de antenas, basada en la estructura radiante de banda ancha strip-slot, y se han diseñado diferentes topologías con características atractivas que contribuyen al estado del arte y son de aplicación en diversos campos, se puede afirmar que esta tesis ofrece una perspectiva nueva para las antenas planares, basadas en elementos no-resonantes

Impedance Transformers

Non

RF MEMS technology for millimeter-wave radar sensors

The dissertation discusses RF MEMS technology for millimeter-wave radar sensors. RF MEMS, which stands for radio frequency micro-electromechanical system, and radar sensor fundamentals are briefly introduced. Of particular interest are: Firstly, a self-aligned fabrication process for capacitive fixed-fixed beam RF MEMS components is disclosed. It enables scaling of the critical dimensions and reduces the number of processing steps by 40% as compared with a conventional RF MEMS fabrication process. Scaling of the critical dimensions of RF MEMS components offers the potential of submicrosecond T/R switching times. RF MEMS varactors with beam lengths of 30 μm are demonstrated using the self-aligned fabrication process, and the performance of a 4 by 4 RF MEMS varactor bank is discussed as well. At 20 GHz, the measured capacitance values range between 180.5 fF and 199.2 fF. The measured capacitance ratio is 1.15, when a driving voltage of 35 V is applied, and the measured loaded Q factor ranges between 14.5 and 10.8. The measured cold-switched power handling is 200 mW. The simulated switching time is 354.6 ns. Secondly, an analog RF MEMS slotline TTD phase shifter is disclosed, for use in conjunction with ultra wideband (UWB) tapered slot antennas, such as the Vivaldi aerial and the double exponentially tapered slot antenna. It is designed for transistor to transistor logic (TTL) bias voltage levels and exhibits a measured phase shift of 28.2°/dB (7.8 ps/dB) and 59.2°/cm at 10 GHz, maintaining a 75 Ω; differential impedance match (S11dd ≤ -15.8 dB). The input third-order intercept point (IIP3) is 5 dBm at 10 GHz for a Δf of 50 kHz, measured in a 100 Ω differential transmission line system.Ph.D.Electrical EngineeringUniversity of Michiganhttp://deepblue.lib.umich.edu/bitstream/2027.42/61348/1/vcaeken.pd