Dissertations / Theses on the topic 'Thin film antennas'

In this thesis a technique that is being used in another area of technology to optimize light reception in a photographic camera was also applied to the dielectric resonator antenna. The technique consisting of the use of thin film to couple the media and camera impedances resulted in a dielectric resonator antenna bandwidth enhancement technique. The bandwidth enhancement technique was found when thin film dielectric layer structure was used to couple the dielectric resonator and its feed mechanism. Remarkable good performance was detected with a coplanar waveguide fed cylindrical dielectric resonator antenna which resulted in an improvement to its fractional bandwidth from 7.41% to 50.85%. Extensive experimental work was undertaken in order to explore the extent offered in bandwidth performance by using thin film dielectric layer structure in the dielectric resonator antenna performance. The experimental tasks were designed in order to investigate the influence of the thin film dielectric layer structure in relation to its size, shape, thickness, position and direction. Experimental results were supported with simulation work with the computer simulation technology microwave studio. The pieces of the material used for undertaking this experimental work were manually handcrafted. Four different dielectric resonator antenna designs were used in order to carry out the experimental work including the coplanar waveguide fed cylindrical dielectric resonator antenna. The other three dielectric resonator antennas were implemented using the same microstrip feed mechanism. Improved performance in bandwidth was achieved for all the designs. Optimization of the incoming signal was observed when a piece of thin film dielectric layer structure was placed in position between the feed mechanism and the dielectric resonator antenna. The optimization was observed as an enhancement in both the return loss level and the bandwidth of work. Different unexpected operational modes from were activated, such modes being called perturbed modes. Two different shapes were used in this project. Cylindrical dielectric resonator antenna (ɛr = 37) from a commercial provider and two novel rectangular dielectric resonator antennas. The novel rectangular dielectric resonator antennas were created with the methodology presented in this thesis. The rectangular dielectric resonator antennas were elaborated with transparent ceramic material (ɛr = 7) and TMM10i (ɛr = 9.8) from the Rogers Corporation company. The bandwidth enhancement technique was tested in novel embedded dielectric resonator antennas. A coplanar waveguide fed embedded cylindrical dielectric resonator antenna achieved a maximum bandwidth enhancement of 156.77% around f = 3.79 GHz with a thin film dielectric layer structure modified rectangular piece on one edge. Escalation to dielectric resonator antenna design at millimeter wave frequencies was achieved by using thin film dielectric layer structure bandwidth enhancement technique and a handcrafted printed circuit board millimeter wave feed mechanism. The millimeter wave feed mechanisms were achieved using a low cost alternative technique conceived as part of this project. Millimeter wave dielectric resonator antennas were implemented using thin film dielectric layers structure. The antennas deliver an adequate performance in bandwidth. The work presented in this thesis demonstrates dielectric resonator antenna simpler geometry, simple couple schemes, small size, low profile, light weight, and ease of excitation and orientation. Other parameters have also been investigated covering reduced complexity, high degree of flexibility, ease of fabrication and the use of low cost technology to escalate to millimeter wave frequencies.

L’évolution rapide des communications sans fil a favorisé l’augmentation du nombre de standards alloués aux systèmes de communication fonctionnant sur différentes bandes de fréquences. Pour accompagner les derniers développements de systèmes sans fil, il est indispensable de concevoir des antennes miniatures intégrables. Cependant, la miniaturisation des antennes s’accompagne d’une réduction significative de la bande passante et de leur efficacité de rayonnement ainsi qu’à l’apparition d’un décalage fréquentiel de leurs fréquences de fonctionnement lorsqu’elles sont étudiées dans leur contexte d’utilisation. L’intégration de dispositifs accordables au sein d 'une antenne permet de répondre favorablement à ces problématiques. Parmi les solutions proposées dans la littérature, l’utilisation de matériaux ferroélectriques en couche mince permet de concevoir un condensateur accordable en fonction du champ électrique appliqué. Ces dispositifs réalisés à base de couches minces ferroélectriques ont été développés pour répondre aux exigences particulières et extrêmes des systèmes de télécommunication actuels (miniaturisation, faible coût, facilité de fabrication et d’intégration et bonne tenue en puissance). Cette thèse s’inscrit dans la continuité des recherches sur les antennes reconfigurables en fréquences à base de matériaux ferroélectriques. Deux axes principaux ont été développés au cours de ces travaux de recherche : le développement et la réalisation de condensateurs intégrant un film BST au sein du laboratoire XLIM et leurs caractérisations en hyperfréquence. La seconde partie de nos travaux concerne l’intégration de l’un de ces dispositifs accordables au sein d’une antenne miniature afin d’étudier son accordabilité en fréquence
The rapid growth of wireless communication has promoted the increase of the number of standards for wireless applications. This progress requests new manufacturing processes of smart devices that are able to work on several frequency bands. However, the miniaturization of antennas is accompanied by a significant reduction of the bandwidth as well as its radiation efficiency and it becomes dependent on its using context. Tunable devices can be integrated within antennas in order to overcome these main issues. Among the solutions proposed in the literature, thin-film ferroelectric materials are used to realize tunable capacitors. The use of such materials allows the design of a tunable capacitor that can be tuned by an applied electric field. The advances of these ferroelectric thin-film devices were developed in order to meet particular and extreme requirements for today's telecommunication systems (miniaturization, low cost, ease of the manufacture process, integration and good power handling). This thesis is part of ongoing research over frequency reconfigurable antennas which are based on ferroelectric materials. Two main axes were developed during this work: The development and realization of capacitors that incorporate a BST film along with their microwave characterizations within XLIM lab. The second part of our work is dedicated to the realization of the complete tunable antenna

Face à la volonté d'intégrer une quantité toujours plus importante de nouveaux services au sein des terminaux mobiles de nouvelle génération et afin de répondre à leurs contraintes d'encombrement, des nouveaux concepts d'antennes intelligentes font l'objet de nombreuses recherches. Parmi les solutions proposées dans la littérature, la technique consistant à charger l'antenne par un matériau aux propriétés commandables apparaît particulièrement intéressante puisque elle cumule les effets de miniaturisation et d'agilité. Le travail de cette thèse concerne l'intégration des films minces La-Ti-O-N et BST dans des antennes miniatures et agiles en fréquence. Pour cela, une étude systématique des propriétés diélectriques (constante, tangente de pertes et accordabilité) des films La-Ti-O-N a été réalisée en basses et hautes fréquences. Ces propriétés sont fonction des caractéristiques structurales des films, elles-mêmes issues de la nature du substrat utilisé et des conditions de dépôt. En parallèle, une étude sur l'intégration de ces matériaux dans des structures rayonnantes pour atteindre l'agilité souhaitée a été menée. De premiers démonstrateurs d'antennes miniatures et reconfigurables à base des films minces La-Ti-O-N et BST ont été réalisés et caractérisés.

Les très basses fréquences (VLF) sont aujourd’hui principalement utilisées pour les communications sous-marines. Ces fréquences ont en effet l’avantage de pénétrer dans l’eau de mer jusqu’à quelques dizaines de mètre de profondeur, ainsi que de permettre des communications à très longue distance, au-delà de l’horizon. Les antennes nécessaires à l’établissement de ces communications sont nécessairement de très petite taille par rapport aux longueurs d’onde mises en jeu. Ces antennes sont des structures composées de centaines de mètre de câbles métalliques, situées à un emplacement étudié pour les qualités diélectriques du sol ou les avantages structurels du relief. Pour étudier de telles antennes, nous proposons l’utilisation d’un code basé sur une méthode temporelle, la TLM. Cette méthode peut se révéler être très efficace pour des études sur de larges bandes de fréquence et en présence d’un environnement diélectrique complexe. Pour cela, nous avons amélioré le modèle du Fil Mince permettant de modéliser une structure métallique en une dimension et avons cherché à valider son fonctionnement en présence d’un environnement réaliste. Dans ce document, nous présentons ainsi les différentes étapes ayant abouties aux améliorations apportées au modèle de Fil Mince. Notre code a été validé en comparant nos résultats à ceux de FEKO, un logiciel commercial basé sur la MoM considéré comme la méthode la plus adaptée à ce type de problème. Nous avons proposé, en particulier, une solution permettant de garantir une bonne précision du modèle quel que soit l’orientation du fil dans le maillage cartésien 3D. Nous avons ensuite précisé le domaine de validité des fils coudés ainsi que des jonctions de plusieurs fils. Nous avons étudié également l’interaction entre le fil et des milieux inhomogènes. Il s’agit là d’une problématique ambitieuse pour laquelle nous avons apporté quelques éléments de réponse mais qui reste à ce jour un verrou technologique à lever. Enfin, nous avons étudié des structures antennaires réalistes. Les simulations d’un système composé d’antennes en T déployé dans une vallée ont permis d’appréhender le fonctionnement d’une telle structure et ont montré l’intérêt de notre méthode. En effet, les temps de calcul nécessaires à la résolution du problème sont significativement plus faibles avec le code TLM qu’avec le logiciel FEKO sur ce type de sol complexe. Les simulations d’une antenne Trideco avec un plan de masse radial aérien ou enterré ont quant à elles montré les limites actuelles du code TLM qui reste handicapé par une modélisation imprécise des nœuds de connexion entre plusieurs fils et de leur interaction avec les milieux inhomogènes
Submarine communications are the main usage of the very low frequency (VLF). This frequency band allows to radiate up to a few tens meter of depth and to a very long distance. Antennas for such telecommunications are necessarily small in regard to the wavelength. However, these structures are composed of hundred meters of thin metallic cables and their locations are often chosen for their dielectric characteristics or the structural advantage provided by the relief. To evaluate such antennas, we propose to use a home-made software, based on the TLM method. Such technique can be efficient for studying wide band electromagnetic problems in complex dielectric environment. Then we have improved the TLM Thin Wire model and we have evaluated its performances in realistic environment. In this document, we present our work and its validation by comparing our results to those obtained with the commercial software FEKO, based on the MoM, considered as the most suitable technique for this kind of problem. A solution assuring a good accuracy of the model for an arbitrary orientation of the Thine Wire in the 3D cartesian grid was proposed. We have also specified the limitations of the bent wire and the wires junction. In addition, we have studied the interaction between the wire and inhomogeneous media. This is an ambitious problem for which we brought some elements of answer but which remains a challenge. Finally, we have tested our software on some realistic antenna systems. The simulations of a valley span T antennas system allow to understand the functioning of such radiating structure and to show the interest of our method. The computation times are significantly lower with the TLM method than with FEKO to deal with antennas above such complex ground. However, the simulations of a Trideco antenna with aerial or buried radial ground plane showed the actual limitations of the TLM software which remains handicapped by an insufficient accuracy of the wires junction model and the inhomogeneous media interactions

L'intégration d'oxydes ferroélectriques permet la réduction des dimensions de dispositifs électroniques pour des applications en télécommunications, tout en leur apportant la reconfigurabilité. Parmi ces matériaux multifonctionnels, KxNa1-xNbO3 (KNN) se présente comme un candidat oxyde sans plomb prometteur pour un grand nombre d'applications. L'objectif de cette thèse est l'élaboration de couches minces de KNN et l'étude de leurs propriétés diélectriques en hyperfréquences en vue de leur intégration dans des antennes miniatures et reconfigurables. La permittivité εr, les pertes tanδ et l'agilité seront caractérisées à partir de couches minces de KNN déposées par la technique d'ablation laser. De plus, les avancements sur les dépôts par pulvérisation cathodique seront présentés. Après une étude sur la composition du matériau, l'influence des propriétés structurales sur les propriété diélectriques à travers l'utilisation de deux types de substrats a permis l'obtention d'une agilité de 20% sous un champ Ebias de 90 kV/cm. Une caractérisation diélectrique en température aura permis d'observer, à 10 GHz, une augmentation de la permittivité de 360 à 20°C jusqu'à 1000 à 240°C au niveau de la transition de phase polymorphique. Lors de ces travaux, la phase bronze de tungstène tétragonale (TTB), encore très peu étudiée dans le système K-Na-Nb-O a été préparée en couches minces fortement orientées et une permittivité élevée a été obtenue à basses (~200 à 10 kHz) et hautes fréquences (~130 à 10 GHz). Enfin la conception, la réalisation et la mesure d'antennes miniatures intégrant du KNN ont été effectuées
Ferroelectric materials are a solution for reducing the size of electronic devices for telecommunication applications while also enabling reconfigurability. Among the multifunctional materials, KxNa1-xNbO3 (KNN) is a promising lead-free oxide for a large number of applications. The main goal of this work is the elaboration of KNN thin films and their dielectric characterisations in order to integrate the thin film to obtain miniature reconfigurable antennas. The permittivity εr, the loss tanδ and the tunability, at microwave frequencies, of the KNN were retrieved from thin films prepared by pulsed laser deposition. Also, the progress on the deposition of KNN thin films by RF magnetron sputtering will be presented. After the investigation of the effect of the composition and the structural properties of the KNN thin films on their dielectric properties, the tunability has been increased up to 20% under a 90 kV/cm electric field for x = 0.5. A dielectric characterisation of depending on the temperature, at 10 GHz, has shown an increase of the permittivity value from 360 at 20°C up to 1000 at 240°C, indicating the polymorphic phase transition. The tetragonal tungsten bronze phase (TTB), barely studied in the K-Na-Nb-O system, has been prepared in thin film and exhibiting high values of permittivity at both low and microwave frequencies (~200 à 10 kHz and ~130 à 10 GHz). Finally the design, realisation and measurements of miniature antennas integrating KNN has been done

Ce travail concerne la réalisation et la caractérisation de dispositifs hyperfréquences agiles en fréquence à base du matériau ferroélectrique KTa1-xNbxO3 (KTN) déposé en couche mince. Doté d'une permittivité diélectrique élevée (er = 700 à 10 GHz et Ebias = 0 kV/cm), KTN est un candidat prometteur pour la reconfigurabilité et la miniaturisation des dispositifs hyperfréquences. Ses pertes restent néanmoins conséquentes (tanδr = 0,3 à 10 GHz et Ebias = 0 kV/cm) et sont en partie à l'origine des pertes globales des dispositifs hyperfréquences réalisés. Afin de limiter ces pertes, une double approche a été engagée : (1) réduction des pertes diélectriques par le dopage du matériau KTN par un oxyde à faibles pertes : MgO à 3% et 6% en moles et (2) réduction des pertes globales par le confinement du matériau KTN dopé dans les zones actives des dispositifs hyperfréquences. Les couches minces de KTN non dopé et dopé d'épaisseur ~ 600 nm ont été déposées sur substrats de saphir orienté R par ablation laser pulsé (PLD). Deux compositions différentes (KTa0,5Nb0,5O3 et KTa0,65Nb0,35O3) ont été sélectionnées pour cette étude. Des dispositifs coplanaires imprimés sur les films ferroélectriques ont été réalisés et caractérisés dans la bande d'intérêt 1 GHz-20 GHz. Le dopage à 6% assure le meilleur compromis pertes / agilité avec une réduction significative des pertes globales de 0,73 à 0,20 (facteur ~ 4) du dispositif résonant imprimé sur KTa0,5Nb0,5O3 après son confinement par microgravure laser. Une agilité en fréquence de 8% est obtenue sous Ebias ≈ 75 kV/cm. L'étude d'une antenne à ondes de fuite reconfigurable en bande Ku a ensuite été mise en oeuvre. Les couches minces de KTa0,5Nb0,5O3 d'épaisseur ~ 600 nm ont été déposées par PLD sur substrats de saphir R, puis le matériau ferroélectrique a été localisé par microgravure laser dans les 6 zones actives de l'antenne (constituée de 6 tronçons). L’évolution du coefficient de réflexion sous Ebias ≈ 85 kV/cm montre une agilité en fréquence égale à 2%. Un gain maximal de 6,7 dBi a été mesuré à f = 17 GHz et Ebias = 0 kV/cm, conformément aux résultats de simulation
This work deals with the fabrication and characterization of frequency tunable microwave devices based on ferroelectric KTa1-xNbxO3 (KTN) thin films. KTN material is a promising candidate for the tunability and miniaturization of microwave devices, due to its high dielectric permittivity (er= 700 at 10 GHz and Ebias= 0 kV/cm). Nevertheless its intrinsic loss (tanδr= 0.3 at 10 GHz and Ebias= 0 kV/cm) strongly impacts the global loss of the tunable microwave devices. To reduce this, a twofold solution has been investigated: (1) reduction of the loss tangent by doping KTN material with a low loss oxide, namely MgO (3% and 6% in mol.) and (2) confinement of the doped KTN film in efficient regions of the microwave devices and removal in noncritical areas by laser microetching. The ~ 600 nm-thick undoped and doped KTN films have been grown by Pulsed Laser Deposition (PLD) on R-plane sapphire substrates. Two different compositions (KTa0.5Nb0.5O3 and KTa0.65Nb0.35O3) were specifically selected for this study. Microwave measurements have been performed on KTN-based coplanar devices from 1 GHz to 20 GHz. Stub resonator printed on confined 6% doped KTa0.5Nb0.5O3 film exhibits the best loss/agility trade-off with a significant global loss reduction from 0.73 to 0.20 (factor ~ 4) with a 8% frequency tunability under Ebias≈ 75 kV/cm.Thereafter, the study of a reconfigurable Ku-band leaky-wave antenna has been carried out. A ~600 nm-thick KTa0.5Nb0.5O3 film was deposited by PLD on R-plane sapphire substrate. The ferroelectric material was localized by laser microetching on 6 specific areas of the antenna (consisted of 6 sections). The variation of the reflection coefficient under biasing (Ebias≈ 85 kV/cm) demonstrates a frequency tunability of 2%. A gain equal to 6.7 dBi has been measured at f= 17 GHz and Ebias= 0 kV/cm, in accordance with the numerical results

In this century some of our main issues are energy shortage and pollution. This work will briefly describe these problems, proposing a plan of action combining energy saving and different sustainable energy sources. Within different types of renewable energy sources, solar energy is the most abundant one. To make solar energy a more sustainable and cost effective technology we focus on enhancing the optical characteristics of thin film solar cells. In this category, organic solar cells are good options for their exiguous amount of material and the low energy needed for the fabrication process. This technology can be lightweight, transparent, flexible and conformal in order to be applied to and integrated in various architectural solutions and consumer electronics. After a study of the physics of such devices and on how to optically enhance their performances, we will show some examples where we theoretically and experimentally collect the solar radiation with optical antennas. We report, for the first time in literature, a nanogap antenna that efficiently couples the light in our active material thin film. Finally, we elaborate on the concept of building integrated photovoltaics introducing some examples of solar façades. Based on our research, we are able to design and fabricate an organic transparent solar cell with a visible transparency above 20% and an optically enhanced photon-electron conversion efficiency remarkably similar to its opaque equivalent.
En el presente siglo, algunas de las prioridades son la escasez de la energía y la contaminación. Este trabajo describirá brevemente estos problemas y propondrá un plan de acción que combina el ahorro energético con diferentes fuentes sostenibles de energía. Dentro de estas fuentes de energía renovables, la energía solar es la más abundante. Con el objetivo de hacer la tecnología solar más sostenible y eficiente económicamente nos concentramos en aumentar las características ópticas en celdas solares de película delgada. Dentro de esta categoría, las celdas solares orgánicas son una buena opción porque su desarrollo requiere bajas cantidades de materiales y su fabricación es de baja energía embebida. Adicionalmente, esta tecnología puede ser liviana, transparente, flexible mecánicamente y modular para ser aplicada e integrada en varias soluciones arquitectónicas y de electrónica de consumo. Luego de estudiar los procesos físicos en tales dispositivos y de determinar las metodologías para aumentar ópticamente sus desempeños, mostraremos algunos ejemplos donde teórica y experimentalmente se colecta la radiación solar mediante antenas ópticas. Se reporta por primera vez, una antena de nanogap que acopla eficientemente la luz en la capa activa de la celda solar. Finalmente, se desarrolla el concepto de tecnología fotovoltaica integrada en edificaciones tras introducir algunos ejemplos de fachadas solares. Basados en nuestra investigación, fue posible diseñar y fabricar una celda solar orgánica transparente cuya transparencia en el rango visible estuvo por encima del 20% y una eficiencia de conversión foton-electron aumentada ópticamente que resulto notoriamente similar a la celda solar orgánica opaca equivalente.
La rareté grandissante des ressources en énergie associée à une augmentation de la pollution font partie des enjeux plus importants de ce siècle. Cette thèse décrira brièvement ces deux problématiques et proposera un plan d’action combinant économie d’énergie et diversité des sources d’énergies renouvelables. Parmi les formes d’énergies renouvelables disponibles, l’énergie solaire est la plus abondante. Pour faire de l’énergie solaire une ressource plus durable et plus rentable économiquement, nous proposons d’amplifier les propriétés optiques de cellules solaires en couches minces. Dans cette catégorie, les cellules solaires organiques représentent un choix pertinent de part la faible quantité de matériau nécessaire ainsi que la faible énergie nécessaire au procédé de fabrication. Cette technologie peut être légère, transparente et flexible de sorte qu’elle peut être utilisée dans différentes solutions architecturales s’adaptant à des produits électroniques pour le grand publique. Suivra la théorie sous jacente à ces dispositifs et l’explication de la manière dont leurs performances sont améliorées. Nous présenterons quelques exemples où l’on collecte la radiation solaire avec une antenne optique. Ainsi, nous faisons la toute première démonstration d’une antenne auto-assemblée qui couple efficacement la lumière dans le matériau constituant la couche mince que nous utilisons. Finalement, nous développons le concept de cellules photovoltaïques intégrées en présentant différents cas de façades solaires. Ces travaux nous ont permis de concevoir et de fabriquer une cellule solaire organique transparente avec une transparence dans le visible de 20% et une efficacité de conversion photon-électron améliorée, similaire à une cellule équivalente opaque.
La difficile reperibilità di risorse energetiche e l’inquinamento sono alcuni dei problemi più importanti di questo secolo. In questo lavoro saranno presentati brevemente questi temi proponendo un piano d’azione che abbini il risparmio energetico alle differenti fonti di energia rinnovabili. Nell’insieme delle fonti energetiche rinnovabili l’energia solare è senz’altro la più abbondante. Con l’obbiettivo di rendere lo sfruttamento di tale energia più sostenibile ed economicamente vantaggioso, ci premuriamo di migliorare le caratteristiche ottiche di celle fotovoltaiche a film sottile. In questa categoria utilizziamo, tra le diverse opzioni, le celle solari organiche in quanto la loro fabbricazione richiede una quantità di materiale minimo e un basso consumo energetico. Inoltre questi tipi di dispositivi possono essere leggeri, trasparenti, flessibili e conformabili alle superfici su cui sono applicati. Questa è una tecnologia che potrebbe essere implementata e integrata in varie soluzioni architettoniche o nell’ elettronica di consumo. Dopo aver presentato i principi fisici di tali dispositivi e determinato le metodologie ottiche per aumentarne le prestazioni, vengono illustrati alcuni esempi dove, teoricamente e sperimentalmente, riusciamo a intercettare la radiazione solare con antenne ottiche. Riportiamo, per la prima volta in letteratura, un’antenna ottica con nano-gap che accoppia efficacemente la luce solare nel nostro materiale attivo a film sottile. Nell’ultima parte sviluppiamo il concetto di tecnologia solare integrata negli edifici, introducendo alcuni esempi di facciate solari. Basando il design sulla nostra ricerca, è possibile realizzare una cella solare fotovoltaica organica trasparente, con una trasparenza superiore del 20% e un’ efficienza di conversione fotone-elettrone migliorata grazie all’ottica, che risulta molto vicina all’ equivalente cella fotovoltaica organica non trasparente.

Recent advances in the electrical conductivity levels of Conducting Polymers (CP) and impressive improvements in their stability are making these materials very attractive potential alternatives to copper in planar antennas. This is particularly so in applications where light weight, inexpensive and/or wearable/conformal antennas are a consideration. There have been isolated efforts in the past towards using CP as material for antenna and transmission line design. This thesis endeavours to provide a systematic study of key factors that are important for the understanding of these materials, their design and simulation as basis material for building microwave antennas. The thesis could be considered as made up of two parts. The first part (Chapter 2 and Appendix A) presents a mathematical model of electrical conduction and permittivity in CPs as a function of dopant concentration and frequency. The electrical conduction and permittivity are very dispersive for these materials primarily due to different relaxation times exhibited by the conduction electrons. This part also develops closed-form expressions formulas for rapid estimation of the effective permittivity of microstrip lines on multi-layer substrates. A 2D finite element eigen-mode analysis leading to the effective permittivity for two and three layer microstrip line structures is used as a reference solution and successfully validates the closed-form expressions. The second part (Chapter 3 and 4) presents the design, simulation and fabrication of microwave antennas using thin CP films. Results on CP based microstrip patch antennas operating at 2 GHz, 4.5 GHz and 6 GHz are presented. This part also presents a systematic study on the impact of CP film thickness, conductivity and fabrication method on antenna performance. An indirect method for determination of the permittivity of non-standard RF substrates and detection of dispersion in the electrical conductivity of CP film has been demonstrated. This part validates the possibility of using CPs as microwave antennas and gives credence to many possibilities in the field of conformal antennas, wearable antennas, sports and medical applications. The thesis is concluded in chapter 5 by summarising the results and presenting some exciting possibilities that these exotic materials open for future applications in the field of antenna applications.
Thesis (Ph.D.) -- University of Adelaide, School of Electrical and Electronics Engineering, 2012

In this dissertation, a carbon nanotube thin-film transistor is fabricated on a flexible substrate. Combined printing and stamping techniques are used for the fabrication. An ink-jet printing technique is used to form the gate, source, and drain electrodes as well as the dielectric layer. A self aligned carbon nanotube (CNT) thin film is formed by using a new modified dip coat technique before being transferred to the device substrate. This novel modified dip-coat technique utilizes the capillary effect of a liquid solution rising between gaps to coat CNT solution on a large area of the substrate while consuming minimal CNT solution. Several key solutions are addressed to solve the fabrication problems. (1) The source/drain contact with the CNT channel is developed by using droplets of silver ink printed on the source/drain areas prior to applying CNT thin. The wet silver ink droplets allow the silver to "wet" the CNT thin-film area and enable good contact with the source and drain contact after annealing. (2) A passivation layer to protect the device channel is developed by bonding a thin Kapton film on top of the device channel. This thin Kapton film is also used as the media for transferring the aligned CNT thin-film on the device substrate. Using this technique, printing the passivation layer can be avoided, and it prevents the inter-diffusion of the liquid dielectric into the CNT porous thin-film. (3) A simple and cost effective technique to form multilayer metal interconnections on flexible substrate is developed and demonstrated. Contact vias are formed on the second substrate prior bonding on the first substrate. Ink-jet printing is used to fill the silver ink into the via structure. The printed silver ink penetrates through the vias to contact with the contact pads on the on the bottom layer, followed by an anneal process. High drain current of 0.476mA was obtained when V[subscript G]= -3V and source-drain voltage (V[subscript DS]) was -1.5V. A bending test was performed on the CNT TFT showing less than a 10% variation in performance. A bending test was also performed on via structures, which yielded less than a 5% change in resistance. The developed CNT TFT is used to form a switch in a phase shifter for a flexible phased-array antenna (PAA). Four element 1-dimensional and 2-dimensional phased-array antennae are fabricated and characterized. Multilayer metal interconnects were used to make a complete PAA system. For a 2-bit 1x4 PAA system, by controlling the ON/OFF states of the transistors, beam steering of a 5.3GHz signal from 0° to -27° has been demonstrated. The antenna system also shows good stability and tolerance under different bending radii of curvature. A 2-bit 2x2 PAA system was also fabricated and demonstrated. Two dimensional beam steering of a 5.2GHz signal at an angle of [theta]=20.7° and [phi]=45° has been demonstrated. The total efficiency of the 1-dimensional and 2-dimensional PAA systems are 42% and 46%, respectively.
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碩士
明新科技大學
電機工程系碩士班
103
In this paper, three materials including glass epoxy (FR4), polyimide film (PI) and photo paper (PP) are used as the substrate of antenna. IE3D software is used to design planar dipole antennas with various substrates.The fabricated planar dipole antenna with FR4 substrate can be applied to 1200MHz and 1800MHz frequency bands, the antenna withPI substrate can be applied to 2100MHz, 4800MHz and 5800MHz frequency bands, and the antenna with PP substrate can be applied to 5300MHz and 5600MHz frequency bands. In this study, the size parameter L2 and the substrate material of antenna are changed to observe the variations of antenna characteristics. The PI film thickness and curing process are discussed in this thesis.The thickness of PI substrate about 0.12mm and two vacuum curing processesare obtained to achieve betterimpedance value. Changing L2 parameters of planar dipole antennas with FR4 substrate, two antennas are proposed in this study.The antenna withbandwidth from1070MHz to 1370MHz,reflection loss -29.3dB and the maximum gain 4.296dBi at 1200MHz can be used for 1200MHz wireless monitors. The antenna with bandwidth from 1.78MHz to 1.98MHz,reflection loss -32.3dB and maximum gain 3.593dBi at 1800MHz can be used in LTE 1800MHz. With suitable L2 parameter, the inkjet printer is used to print silver nanoparticles and fabricate three flexible thin-film antennas with PI substrates. The bandwidths of these antennas are from 1500MHz to 2500 MHz,4200 MHz to 4950 MHz and 5400 to 5800 MHz.The reflection loss is -17.6dB and maximum gain is 2.183dBi at 1200MHz. The reflection loss is -38.9dB and maximum gain is 3.509dBi at 4800MHz. The reflection loss is -16.4dB and maximum gain is 3.599dBi at 5800MHz. These antennas can be applied to LTE 2100MHz, C-Band 4800MHz, and WLAN (801.11ac) 5800MHz frequency bands. PP substrate, suitable L2 parameter, and silver nanoparticles are used to produce three flexible thin-film antennas with PP substrates. The bandwidths of these antennas are from 5100MHz to5500MHz, 4600MHz to 5400MHz, and5300MHz to 5700MHz.One antenna exhibits reflection loss-22.5dB,maximum gain3.257dBi at 5300MHz and another antenna with reflection loss -37.6dB andmaximum gain4.175dBiat 5300MHz. The reflection loss is -32.4dB and the maximum gain is 4.834dBi at 5600MHz. These antennas can be applied to WLAN (801.11ac) 5300MHz, WLAN (801.11ac) 5600MHz. Keywords: planar dipole antenna, silver nanoparticles, flexible thin-film,LTE, WLAN, PI, PP.

碩士
長庚大學
化工與材料工程學系
99
Smart phones are getting lighter, thinner and smaller, and the trend will initiate a new set of requirements for the antenna; therefore, the antenna design has been highlighted with a great importance that the antenna should be embedded inside a smart phone. Also, the film antenna, which can decrease the side of an antenna, is going to be another trend in design. At the moment, the antenna design mainly lies on the embedded antennae techniques; namely, there are Hot Melting, Flexible PCB and Laser Direct Structuring (LDS). The new technique, LDS, is to construct an antenna on the mobile phone case. Compared with traditional antennae, the LSD antenna is more complex and more expensive. Based on two metallic-thin-film manufacturing processes-LDS and Sputtering, this study is to explore the distinct features of the manufacturing process with the metallic thin film in three different thicknesses. Firstly, deposit metallic copper in three different degree thicknesses and use them as the materials of the antenna electric conductive circuit. Secondly, deposit three kinds of metallic nickel with the same thickness and use them prevent the metallic copper from oxidizing so as to make the substrate become an electrical conductive thin-film antenna. To compare the values of the antennae produced in different manufacturing processes, each antenna will be used to measure its Return-Loss value. The smaller the Return-Loss value is, the better the antenna will be. In virtue of the easy control of the film thickness of Sputtering and its highly well-mixed and mass-production feature, the cost saving purpose can be reached by the advantage of decreasing the film thickness and raising the production yield.

碩士
國立聯合大學
電機工程學系碩士班
105
Ni0.5(Ti0.3Zr0.7)0.5NbO4 thin films were deposited on Si(100) substrate by RF magnetron sputtering have been studied. Effects of physical and electrical properties of Ni0.5(Ti0.3Zr0.7)0.5NbO4 thin films with fixed a working pressures of 3mTorr at various RF powers (175~225W), substrate temperatures (200~400℃), Ar/O2 ratio (10/0~8/2), annealing temperatures (600~800℃) and annealing atmospheres (Air, Oxygen) for 1hr have been investigated. The experimental results reveal the optimum condition for working pressure of 3mTorr, RF power of 225W, Ar/O2=10/0 and annealing temperature of 700℃ in oxygen atmosphere, which possess a dielectric constant of 34.76 (f=1MHz), a dissipation factor of 0.05 (f=1MHz), a leakage current density of 2.67×10-8A/cm2 at an electrical field of 20kV/cm. On the other hand, experimental results also reveal a dielectric constant of 5.14 (f=900MHz), a dissipation factor of 0.092 (f=900MHz) through rf frequency measurement. Finally, the best result of the above prepared substrate for thin film antenna design simulation and to explore its properties.

碩士
國立聯合大學
電機工程學系碩士班
105
CaLa4(Zr0.05Ti0.95)4O15 thin films were deposited on Si(100) substrate by rf magnetron sputtering have been studied. Effects of physical properties and electrical of CaLa4(Zr0.05Ti0.95)4O15 thin films with fixed working pressures 3mTorr, rf powers 100W, substrate temperatures (200oC、250oC、300oC), O2/Ar ratios (0/10~2/8), and annealing temperature (800oC、900oC) in oxygen for 1hr also have been investigated. The experimental results can be learned, the optimum conditions for CaLa4 (Zr0.05Ti0.95)4O15 films were obtained at a working pressureto 3mTorr, an annealing temperature at 800oC in oxygen atmosphere, a RF power 100W, a substrate temperature of 300oC and an O2/Ar =0/10. In this condition, the CaLa4 (Zr0.05Ti0.95)4O15 film possesses a low frequency (1MHz) dielectric constant of 16.3, a low frequency dissipation factor of 0.215, a leakage current density of 4.2×10-9 A/cm2 at an electrical field of 100 kV/cm. According to the reference[2][3] and the results of this experiment to measurement for thin film high frequency dielectric properties.When CaLa4 (Zr0.05Ti0.95)4O15 films were deposited by rf powers 300W, working pressures 3mTorr, a substrate temperature of 300oC, O2/Ar =2/8, an annealing temperature at 900oC in air atmosphere, its excellent high frequency dielectric constant of 4.3 , a high frequency dissipation factor of 0.39.Finally,the best result of the above prepared substrate for thin film antenna design simulation and to explore its properties.

碩士
國立臺灣科技大學
電機工程系
100
This thesis proposes first the design of the inverted-F antenna (IFA) which can operate in digital audio broadcasting (DAB) band III (170-240 MHz) for digital broadcasting services and in-car entertainment applications. In this design, a matching stub has been added to a pair of strips resonating at λ/4 lengths for tuning the input impedance to the DAB band. The return loss of the antenna is larger than 6dB in the whole DAB band. The proposed antenna has a simple structure and proper size, which can reduce blockages to driver’s visions. This antenna is fairly appropriate to be implemented into a thin-film type and attached on the windshield of the car. The antenna design is to reduce manufacture cost and allow convenient installations. Moreover, the logo of the collaborating company is used as part of the antenna, which can provide anti-counterfeit, have a better antenna identification and even perform better. Good agreements between simulations and measurements are obtained. Furthermore, for DTV applications, an inverted-F film antenna with the similar structure as the DAB antenna is designed for operating in the DTV band of Taiwan (500-650 MHz). Based on simulations, good performances in return loss, gain, and efficiency are obtained, which may be employed for practical applications.

博士
義守大學
電子工程學系博士班
99
In this dissertation, the technology of thermal evaporation has been utilized to grow the organic semiconductor thin film being functioned as active device and embedded into microstrip patch antenna. Meanwhile, for the microstrip patch antenna with embedded organic semiconductor thin film active device, the antenna gain can be justified without changing the operation frequency. By using of nematic liquid crystals (NLC) technology, we can detect the absorption electromagnetic energy band of p-type organic semiconductor thin film of NIQ to confirm that the microwave energy in radio frequency band would not be perturbed by NIQ organic thin film devices. Comparatively, not only the carrier drifting velocity is very slow in organic thin film and the references for the organic semiconductor thin film device embedded microstrip patch antenna are little, but also the P-N junction and channel current, building potential, energy states distribution, trap density and the channel impendence for the organic semiconductor thin film transistor are much more complicated than the inorganic ones. The study of the organic semiconductor thin film active device embedded to the microstrip is thus an interesting topic. The only choice for the flexible substrate for the applications in RFID antenna is organic semiconductor thin film device because of its conformational specialty. Organic thin film devices can be conformal to the tag with flexible configurations. We tried to use side probe fed to connect the organic thin film active device deposited upon the FR4 substrate to the microstrip patch antenna. Surprisingly, we could activate the organic thin film active device and microstrip patch antenna simultaneously at the same resonant frequency. The active device can directly justify the antenna gain and the patterns of far fields. Therefore, this kind of design can be used for RFID microstrip patch antenna without using external bias to activate the device. In theory, two problems are concerned. First is how to analyze and model an interface between the organic thin film and metal and the second is how to embed the I-V characteristic curve for the microstrip patch antenna. To solve the problem, we put forward the characteristics of solution, first, S11 value is used as equivalent circuitry for organic semiconductor field effect transistor and contact impendence for the interface between the thin film and metal, and then, other components in scattering matrix are used as the coupling to connect the leaky layer (thin film) presented by dielectric coefficient and loss tangent (substrate) as well as the I-V curve of the device. Practically, we successfully activate the device bias at 0.5 ~ 1.5 volt for diodes and transistors by properly probe fed through microstrip patch antenna. In conclusion, organic semiconductor thin film devices including diode and transistor used as the embedded active device can be applicative being embedded to the microstrip patch antenna. The organic semiconductor thin films including NIQ, Alq3, ZnBIP, CuPC and C60 were all discussed and applicative to the design of organic semiconductor thin film device as the parasitic components for the microstrip antenna. The experimental results revealed the major characteristics of junction currents along metal-organic material interface, ohm contact resistance between the electrodes of source and drain in organic semiconductor thin film transistor and the leaky effect of the organic semiconductor layers for the microstrip antenna. Further investigation about the advance topics including the full understanding of the energy levels and the surface charge transport at metal-organic material interface is well planned for future research.

碩士
正修科技大學
電機工程研究所
97
This thesis has investigated the characteristics of loading parasitic organic semiconductor thin film on the patch radiator of circular polarization microstrip antenna through changing of thickness of parasitic thin film, adjusting antenna design, calculation of conductivity, dielectric coefficient as well as the analysis of loss tangent and mobility of the thin film-antenna combinational.The experimental result has shown that, the parasitic thin film can influence the circular polarization of the microstrip antennas, the returns lose, the bandwidth and the impedance, axial ratio, field shape and the antenna gain. This thesis also presented a novel design of organic suberstrate layer circuit for a new development of thin film parasitic.

碩士
國立清華大學
電子工程研究所
101
In this thesis, device quality amorphous silicon and polycrystalline silicon thin films were investigated for fabricating SPA solar cells by using ICP-CVD with internal low-inductance antenna (LIA). For polycrystalline silicon thin films, we observed that 98% of hydrogen dilution ratio with a SiH4 flow rate of 2 sccm and H2 flow rate of 98 sccm are suitable. Furthermore, higher power of 3000 W and higher temperature of 400℃ and 10mT process pressure increased the crystalline volume fraction Xc of poly-Si films. Annealing the substrates at 350℃ in vacuum chamber for 30 minutes before depositing the films also could enhance the quality of poly-Si film and the highest Xc obtained was 82.63% on the glass substrate. The highest conductivity of n-type poly-Si thin-film which was obtained with the doping gas PH3 diluted in 99% H2, was1.916 Ω-1-cm-1. Hydrogenated amorphous silicon films were fabricated by tuning the process parameters to lower power of 1500 W, lower temperature of 200℃, and lower hydrogen dilution of 77%, and the band gap obtained was 1.75 eV, and the Raman spectra of this film showed a peak at 480cm-1. In the case of p-type amorphous silicon thin films, the conductivity obtained was 0.315 Ω-1-cm-1. For the highest band gap of 1.705 eV with the doping gas B2H6 diluted in 99.5% H2. We fabricated the single heterojunction thin-film Si solar cell with poly-Si and a-Si:H absorber layers (SPA) and the highest efficiency of 2.4 % was obtained. After replacing the p-type amorphous layer and absorber amorphous layer with higher band gap deposited in NTCU, efficiency improved to 3.24 %.