A Comprehensive Survey of 'Metamaterial Transmission-Line Based Antennas: Design, Challenges, and Applications'

In this review paper, a comprehensive study on the concept, theory, and applications of composite right/left-handed transmission lines (CRLH-TLs) by considering their use in antenna system designs have been provided. It is shown that CRLH-TLs with negative permittivity (epsilon < 0) and negative permeability (mu < 0) have unique properties that do not occur naturally. Therefore, they are referred to as artificial structures called "metamaterials". These artificial structures include series left-handed (LH) capacitances (C-L), shunt LH inductances (L-L), series right-handed (RH) inductances (L-R), and shunt RH capacitances (C-R) that are realized by slots or interdigital capacitors, stubs or via-holes, unwanted current flowing on the surface, and gap distance between the surface and ground-plane, respectively. In the most cases, it is also shown that structures based on CRLH metamaterial-TLs are superior than their conventional alternatives, since they have smaller dimensions, lower-profile, wider bandwidth, better radiation patterns, higher gain and efficiency, which make them easier and more cost-effective to manufacture and mass produce. Hence, a broad range of metamaterial-based design possibilities are introduced to highlight the improvement of the performance parameters that are rare and not often discussed in available literature. Therefore, this survey provides a wide overview of key early-stage concepts of metematerial-based designs as a thorough reference for specialist antennas and microwave circuits designers. To analyze the critical features of metamaterial theory and concept, several examples are used. Comparisons on the basis of physical size, bandwidth, materials, gain, efficiency, and radiation patterns are made for all the examples that are based on CRLH metamaterial-TLs. As revealed in all the metematerial design examples, foot-print area decrement is an important issue of study that have a strong impact for the enlargement of the next generation wireless communication systems

A comprehensive survey of "metamaterial transmission-line based antennas: design, challenges, and applications"

In this review paper, a comprehensive study on the concept, theory, and applications of composite right/left-handed transmission lines (CRLH-TLs) by considering their use in antenna system designs have been provided. It is shown that CRLH-TLs with negative permittivity (ε < 0) and negative permeability (μ < 0) have unique properties that do not occur naturally. Therefore, they are referred to as artificial structures called "metamaterials". These artificial structures include series left-handed (LH) capacitances (CL), shunt LH inductances (LL), series right-handed (RH) inductances (LR), and shunt RH capacitances (CR) that are realized by slots or interdigital capacitors, stubs or via-holes, unwanted current flowing on the surface, and gap distance between the surface and ground-plane, respectively. In the most cases, it is also shown that structures based on CRLH metamaterial-TLs are superior than their conventional alternatives, since they have smaller dimensions, lower-profile, wider bandwidth, better radiation patterns, higher gain and efficiency, which make them easier and more cost-effective to manufacture and mass produce. Hence, a broad range of metamaterial-based design possibilities are introduced to highlight the improvement of the performance parameters that are rare and not often discussed in available literature. Therefore, this survey provides a wide overview of key early-stage concepts of metematerial-based designs as a thorough reference for specialist antennas and microwave circuits designers. To analyze the critical features of metamaterial theory and concept, several examples are used. Comparisons on the basis of physical size, bandwidth, materials, gain, efficiency, and radiation patterns are made for all the examples that are based on CRLH metamaterial-TLs. As revealed in all the metematerial design examples, foot-print area decrement is an important issue of study that have a strong impact for the enlargement of the next generation wireless communication systems

Compact Reconfigurable Antennas for Wireless Systems and Wearable Applications

The fast growth of wireless communications has driven the necessity of exploiting technological solutions for the needs of faster connectivity. While bandwidth allocation and effective radiated power (ERP) are subjected to regulatory constrain, alternative solutions have been developed to overcome the challenges that arise in terms of wireless coverage and number of users. Reconfigurable antennas (RAs) technology is one of the hardware solutions developed to enhance the connectivity between wireless devices. These new class of radiating elements are able to adapt their physical characteristics in response to the environmental changes or users density and location. Reconfigurable antennas can be divided into two main categories: frequency reconfigurable antennas and pattern reconfigurable antennas. The former class of RAs are able to switch the operational frequency in order to move the communication within unoccupied channels. The latter category defines those antennas that are able to change their radiation characteristics (radiation pattern or polarization) in response to the dynamics of the surrounding environment. Unlike conventional static antennas where the energy is wasted around the surrounding space, the use of RAs allows for a smarter management of the radiated energy as the beam can be focused toward specific directions. As a result, not only data throughput between two devices can be improved but also the interference between adjacent networks can be reduced significantly. n this PhD thesis we focus on the design, prototyping and system application of compact RAs for wireless base stations and mobile devices. Specifically, the first task focuses on the design of a compact reconfigurable antenna capable of generating omnidirectional and directional beams in a single planar design. Next, we propose to apply a miniaturization technique in order to drastically reduce the size of Composite Right-Left Handed Reconfigurable Leaky Wave Antennas (CRLH RLWAs). The large beam steering capabilities along with the miniaturized dimension open new venues for the integration of this antenna technology into mobile devices such as laptop or tablets. Similarly for electrically reconfigurable antennas, characteristics such as input impedance and radiation properties of a radiating element can vary by mechanically change its physical dimension. In other words, instead of changing the metallic geometry through electrical components, the characteristics of an antenna can be changed through physical deformation of its geometry. This principle addresses the second main application of reconfigurable antennas this PhD thesis. Wearable technologies are gaining a lot of attentions due to their strong potential for sensing, communication and tactile interaction applications. Thanks to the progress in knitting facilities and techniques, smart fabrics are generally implemented through sewn-in sensors especially in the fields of medical and athletic applications. Such wearable sensors provide a means to monitor the wearers health through physiological measurements in a natural setting or can be used to detect or alert care providers to potential hazards around the wearer. The feasibility of building electrical devices using conductive fabrics has been analyzed through electrical characterization of textile transmission lines and antennas where conductive fabrics have been applied onto woven fabrics have been demonstrated in recent literature. Previous works show conductive copper foils or fabrics bonded to a flexible substrate. However, these techniques show limitations in terms of electrical losses caused by adhesives or glue chemicals. It is desirable to address these drawbacks by knitting conductive and non-conductive yarns in a single process resulting in smart textiles that are unobtrusively integrated into the host garment so as to eliminate the need for chemical adhesives that degrade electrical performance. The characteristics variations of a fabric-based antenna under physical deformations can be exploited to provide a fully wireless sensing of certain body movements. The second task of this PhD thesis, focuses on the design and testing of these purely textile wireless sensors for biomedical applications. The Radio-Frequency Identification (RFID) technology will be applied fordesigning fabric-based strain sensors through the use of novel inductively-coupled RFID microchips (MAGICSTRAP). As opposed to conventional surface-mount microchips, the MAGICSTRAP does not require any physical soldering connection as the RF energy is inductively coupled from the microchip pads to the antenna arms. A separate interrogator unit can communicate with this knit passive RFID architecture by sending a probing signal; the backscattered component received from the knit tag will indicate the level of stretch, and this information will be translated in the physical phenomenon being monitored. The change in the electrical characteristics of the textile antenna, along with the decoupling of the MAGICTRAP chip allow for more reliable detection of contraction/elongation movements. This study will include comprehensive design and characterization of the textile tag sensor along with performance analysis using a mechanical human mannequin.Ph.D., Electrical Engineering -- Drexel University, 201

Использование метаматериалов для улучшения электрических характеристик антенных устройств: обзор

Монография посвящена обзору современных исследований в области улучшения электрических характеристик антенных устройств с помощью метаматериалов. Даны физические принципы работы метаматериалов в видимом, инфракрасном и сверхвысокочастотном диапазонах. Проанализирован круг антенных задач, на решение которых направлено использование материалов с отрицательным коэффициентом преломления. Рассмотрены вопросы построения частотно-селективных поверхностей на основе метаматериалов, радиопоглощающих покрытий, антенн с малым электрическим размером. Приведен обзор работ, связанных с технологиями создания наноантенн в видимом и инфракрасном диапазонах, основанных на современных достижениях наноплазмоники. Монография предназначена для научных работников и инженеров, занимающихся разработкой и проектированием миниатюрных антенн и устройств обработки сигналов в сверхвысокочастотном диапазоне, а также специалистов по наноплазмонике. Также монография будет полезна для обучающихся по направлению «Радиотехника» бакалавриата и магистерских программ при изучении разделов дисциплин, связанных с электродинамикой, антеннами, устройствами сверхвысокой частоты, оптикоэлектроникой и наноэлектроникой

Tatsuo Itoh : discurs llegit a la cerimònia d'investidura celebrada a la Sala d'Actes del Rectorat el dia 14 d'octubre de l'any 2015

Tatsuo Itoh va ser investit doctor honoris causa per la UAB per les seves rellevants contribucions a l'enginyeria de radiofreqüència/microones i de les telecomunicacions.Nomenament 19/03/2015. A proposta de l'Escola d'Enginyeria. L'acte d'investidura va tenir lloc el 14 d'octubre de 201

Metamaterial-loaded printed antennas : design and application

Wireless communication systems have grown dramatically during the last few years. Moreover, these systems have achieved a great popularity in society. Several examples can be mentioned: cellular communications (GSM, DCS, UMTS), personal area networks (Bluetooth), local area wireless networks (WiFi), radionavigation systems (GPS), etc. The current trend consists of using only one user terminal for several standards (e. g. GSM and UMTS terminals) and for more than one service (e. g. cellular communications, radionavigation systems and personal area networks). In addition, it is also important to note that current user terminals are more and more compact. For these reasons, it would be desirable to use only one antenna for all the standards and/or services covered by the terminal. However, it is important to note that each standard or service requires different antenna characteristics in terms of operating frequency and optimal radiation performance (radiation pattern, polarization, etc.). Hence, compact antennas with multifrequency (simultaneous operation over two or more bands) and multifunction performance (radiation pattern or polarization diversity, frequency reconfigurability, etc.) are a good solution as the radiating element of hanheld terminals. Furthermore, similar arguments can be made to justify the huge demand on multifrequency and multifunction compact antennas for the network elements such as base stations, hot-spots and other access points. Additionally, novel proposals, such as Cognitive Radio, and emerging radio applications like RFID are challenging from antenna engineering point of view. It is important to take into account that the antennas with the optimal characteristics stated above are very difficult to achieve by using conventional techniques. Thus, novel approaches are being developed to obtain radiating elements with the desired characteristics. One of these techniques is the use of metamaterial structures. Metamaterials can be broadly defined as electromagnetic structures engineered to achieve exotic or unusual properties. These features have been used in microwave engineering to develop devices with extraordinary properties such as miniaturization or operation over multiple frequency bands. On the other hand, the effort in the antenna field has been put on the use of metamaterials for travelling-wave antennas and as substrates and superstrates for antennas. Recently, there has been a great effort on miniaturized antennas based on metamaterial concepts. Nevertheless, from the author's point of view, the possibility of achieving multifrequency and/or multifunction antennas based on metamaterials has not been fully explored. The main goal of the proposed Thesis is the development of a novel design approach called metamaterial-loaded printed antennas. This solution consists of loading a conventional printed antenna with a set of metamaterial particles. Hence, the bene ts of printed antennas (low cost, compactness, low pro le, light weight, simplicity to integrate with circuitry and usefulness as elements for antenna arrays) are kept. Furthermore, the desired additional characteristics such as multifrequency and multifunction performance are obtained thanks to the proper design of the metamaterial loading elements. Several metamaterial-loaded printed antennas are proposed to provide solutions for a broad range of applications. In particular, two types of printed antennas are considered: printed wire antennas and microstrip patch radiators. The methodology used throughout the Thesis is the following: firstly, approximate models based on transmission line theory and equivalent circuits are developed to analyse and design the proposed antennas with low computational cost. Then, a full-wave study is carried out by making use of commercial and home-made solvers. Finally, the designed antennas are manufactured and measured to check their performance. Two different classes of wire antennas are proposed: printed dipole antennas loaded with metamaterial particles and printed wire antennas over ground plane with Left-Handed (LH) metamaterial loading. Regarding the dipole antennas, a multifrequency performance is achieved because these antennas have additional working bands close to the self-resonance frequencies of the metamaterial loading particles. Moreover, miniaturization is achieved when the additional modes are placed below the resonance frequency of the unloaded dipole. On the other hand, the use of LH loading allows developing antennas over ground plane (the monopole and half-loop antenna over ground plane) with additional features and small dimensions. The second type of antennas is microstrip patch antennas filled with metamaterial structures. Multifrequency and multifunction microstrip patch antennas are developed using this approach. In addition, this technique is extended to achieve multifunction patch antennas with polarization diversity and multifrequency performance. In particular, two applications are proposed: quad-frequency patch antennas with polarization diversity and dualfrequency circularly polarized patch antennas. Finally, it is proposed the application of the metamaterial-loaded antennas not as isolated radiating elements, but integrated into systems or antenna arrays. Specifically, the proposed dipole antennas are used to enhance the performance of log-periodic antenna arrays. Moreover, it is shown that metamaterial-loaded antennas are a good solution to fulfil the requirements of future communications systems (Cognitive Radio) and emerging applications such us RFID.---------------------------------------------------------------------------------------------------Los sistemas de comunicaciones inalámbricos han experimentado un enorme crecimiento en los últimos años. Prueba de ello es que varios de estos sistemas han logrado una gran popularidad. Podemos mencionar los ejemplos de la telefonía móvil (GSM, DCS, UMTS), las redes de área personal (Bluetooth), las redes locales inalámbricas (WiFi), los servicios de radionavegación (GPS), etc. La tendencia actual consiste en emplear un único terminal de usuario para diferentes normas (por ejemplo los terminales que funcionan en GSM y UMTS simultáneamente) y para varios servicios distintos (como los terminales que proporcionan los servicios de telefonía móvil, radionavegación y redes personales). Además, es importante tener en cuenta que los terminales cada vez son más compactos. Por estas razones, sería deseable emplear una única antena para todas las normas y/o servicios en los que funcione el terminal. Sin embargo, hay que tener en cuenta que cada norma o servicio requiere unas características diferentes de la antena tanto desde el punto de vista de la frecuencia de funcionamiento como de las características de radiación (diagrama de radiación, polarización, etc.) De este modo, las antenas compactas con propiedades de multifrecuencia (funcionamiento simultáneo en dos o más bandas de frecuencia) y multifunción (diversidad de diagramas de radiación, reconfigurabilidad en frecuencia, etc.) resultarían una buena solución como elementos radiantes de los terminales de usuario. Además, se pueden considerar argumentos similares para justificar la enorme demanda de antenas multifrecuencia y multifución para los elementos de red como estaciones base, hot-spots y otros puntos de acceso a redes inalámbricas. No podemos obviar tampoco que las nuevas propuestas como los sistemas de radio cognitiva (Cognitive Radio) y otras aplicaciones inalámbricas emergentes como la identificación por radiofrecuencia (RFID) suponen una serie de retos desde el punto de vista de la ingeniería de antenas. Debemos tener en cuenta que es muy difícil diseñar antenas con todas las características mencionadas anteriormente mediante el empleo de las técnicas convencionales. Por esta razón, se están proponiendo nuevas técnicas para el desarrollo de elementos radiantes con las características optimas deseadas. Ona de estas nuevas técnicas está basada en el empleo de las denominadas estructuras metamateriales. Los metamateriales se pueden definir de manera amplia como estructuras electromagnéticas diseñadas para obtener propiedades exóticas o no comunes. Estas características se han empleado en el ámbito de la ingeniería de microondas para el desarrollo de dispositivos con características extraordinarias como son la miniaturización o multifrecuencia. En cambio, en el ámbito de la ingeniería de antenas se han empleado para el diseño de antenas de onda viajera (por ejemplo leaky-wave) y como sustratos o superestratos para antenas. Más recientemente, se ha realizado un gran esfuerzo para obtener antenas miniaturizadas basadas en los conceptos de estructuras metamateriales. Sin embargo, desde el punto de vista del autor, la posibilidad de obtener antenas multifrecuencia y/o multifunción basadas en estructuras metamateriales no ha sido totalmente explotada. El principal objetivo de esta tesis doctoral es el desarrollo de una novedosa técnica de diseño de antenas consistente en cargar una antena impresa convencional con partículas metamateriales. Por este motivo denominamos este conjunto antenas impresas cargadas con partículas metamateriales. Mediante el empleo de esta técnica se mantienen los beneficios de las antenas impresas (bajo coste, antenas compactas y de bajo perfil, bajo peso, simplicidad para integrarlas con circuitería y como elementos en agrupaciones de antenas). Además, se consiguen una serie de características deseadas como multifrecuencia y multifuncionalidad gracias al empleo de las partículas materiales que se emplean para cargar la antena. En concreto, se proponen dos clases de antenas impresas cargadas con partículas metamateriales con el objetivo de cubrir el amplio espectro de aplicaciones que requieren antenas con dichas características. Las dos clases de antenas propuestas son las antenas de hilo impresas cargadas con partículas metamateriales y las antenas de parche parcialmente rellenas de estrucutras metamateriales. La metodología que se sigue durante el desarrollo de esta tesis doctoral es la siguiente: en primer lugar se proponen modelos aproximados de bajo coste computacional basados en la teoría de líneas de transmisión y equivalentes circuitales para el análisis y diseño de las antenas propuestas. A continuación, se realizan simulaciones de onda completa empleando simuladores comerciales y una solución propia del método de los momentos. Finalmente, las antenas diseñadas se fabrican y se miden para comprobar sus prestaciones. Se proponen dos tipos de antenas de hilo impresas: dipolos cargados con partículas metamateriales y antenas de hilo impresas sobre plano de masa cargadas con líneas metamateriales zurdas (conocidas como Left-Handed o LH en la bibliografía técnica). En lo que respecta a los dipolos cargados con partículas metamateriales, se obtiene la característica de multifrecuencia debido a que estas antenas presentan bandas de funcionamiento adicionales próximas a las frecuencias de resonancia de las partículas metamateriales que se emplean para cargarlas. Además, es posible obtener la característica de miniaturización ya que los modos adicionales pueden resonar por debajo de la frecuencia fundamental del dipolo convenconal sin cargar. En cambio, el empleo de estructuras LH en las antenas sobre plano de masa (como son el monopolo y el semilazo sobre plano de masa) proporcionan características adicionales y miniaturización respecto a las antenas convencionales sin cargar. La segunda clase de antenas propuestas son los parches parcialmente rellenos de estructuras metamateriales. El empleo de esta técnica permite el diseño de antenas de parche con las propiedades de multifrecuencia y multifunción. Además, esta técnica se puede emplear también para obtener antenas multifrecuencia con diversidad de polarización. En concreto, se proponen dos aplicaciones distintas: parches de cuádruple frecuencia con diversidad de polarización y parches de doble frecuencia con polarización circular. Finalmente, se propone el empleo de las antenas impresas cargadas con partículas metamateriales no como elementos radiantes aislados, sino integradas en sistemas y agrupaciones de antenas. Por ejemplo, los dipolos impresos multifrecuencia se utilizan para mejorar las características de las agrupaciones log-periódicas. Además, se demuestra que las antenas propuestas son unas buenas candidatas para satisfacer los requisitos de los sistemas de comunicaciones futuros (como Cognitive Radio) y las aplicaciones emergentes como RFID

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