This thesis presents a study of impedance optimisation of active microstrip patch antennas to multiple frequency points. A single layered aperture coupled microstrip patch antenna has been optimised to match the source reflection coefficient of a transistor in designing an active antenna. The active aperture coupled microstrip patch antenna was optimised to satisfy Global Positioning System (GPS) frequency specifications. A rudimentary aperture coupled microstrip patch antenna consists of a rectangular antenna element etched on the top surface of two dielectric substrates. The substrates are separated by a ground plane and a microstrip feed is etched on the bottom surface. A rectangular aperture in the ground plane provides coupling between the feed and the antenna element. This type of antenna, which conveniently isolates any circuit at the feed from the antenna element, is suitable for integrated circuit design and is simple to fabricate. An active antenna design directly couples an antenna to an active device, therefore saving real estate and power. This thesis focuses on designing an aperture coupled patch antenna directly coupled to a low noise amplifier as part of the front end of a GPS receiver. In this work an in-house software package, dubbed ACP by its creator Dr Rod Waterhouse, for calculating aperture coupled microstrip patch antenna performance parameters was linked to HP-EEsof, a microwave computer aided design and simulation package by Hewlett-Packard. An ANSI C module in HP-EEsof was written to bind the two packages. This process affords the client the benefit of powerful analysis tools offered in HP-EEsof and the fast analysis of ACP for seamless system design. Moreover, the optimisation algorithms in HP-EEsof were employed to investigate which algorithms are best suited for optimising patch antennas. The active antenna design presented in this study evades an input matching network, which is accomplished by designing the antenna to represent the desired source termination of a transistor. It has been demonstrated that a dual-band microstrip patch antenna can be successfully designed to match the source reflection coefficient, avoiding the need to insert a matching network. Maximum power transfer in electrical circuits is accomplished by matching the impedance between entities, which is generally acheived with the use of a matching network. Passive matching networks employed in amplifier design generally consist of discrete components up to the low GHz frequency range or distributed elements at greater frequencies. The source termination for a low noise amplifier will greatly influence its noise, gain and linearity which is controlled by designing a suitable input matching network. Ten diverse search methods offered in HP-EEsof were used to optimise an active aperture coupled microstrip patch antenna. This study has shown that the algorithms based on the randomised search techniques and the Genetic algorithm provide the most robust performance. The optimisation results were used to design an active dual-band antenna.

Els serveis de telecomunicacions i sistemes radar estan migrant a freqüències mil•limètriques (MMW), on es disposa d 'una major amplada de banda i conseqüentment d'una major velocitat de transmissió de dades. Aquesta migració requereix de l'ús de diferents tecnologies amb capacitat d'operar a la banda de freqüències mil•limètriques (30 a 300 Ghz), i més concretament en les bandes Ka (26,5 - 40GHz), V (50 – 75GHz) i W (75 – 110GHz). En moltes aplicacions i sobretot en aquelles on l'antena forma part d'un dispositiu mòbil, es cerca poder utilitzar antenes planes, caracteritzades per tenir unes dimensions reduïdes i un baix cost de fabricació. El conjunt de requeriments es pot resumir en obtenir una antena amb capacitat de reconfigurabilitat i amb un baix nivell de pèrdues en cada una de les bandes de freqüència. Per tal d'afrontar aquests reptes, les dimensions de les antenes mil•limètriques, juntament amb els tipus de materials, toleràncies de fabricació i la capacitat de reconfigurabilitat ens porten a l'ús de processos de microfabricació. L'objectiu d'aquesta tesis doctoral és l'anàlisi dels conceptes mencionats, tipus de materials, geometries de línia de transmissió i interruptors, en el context de les freqüències mil•limètriques, així com la seva aplicació final en dissenys d'antenes compatibles amb els processos de microfabricació. Finalment, com a demostració s'han presentat dissenys específics utilitzables en tres aplicacions a freqüències mil•limètriques: Sistemes de Comunicació per Satèl•lit (SCS) a la banda Ka, Xarxes d'àrea personal inalàmbriques (WPAN) a la banda V i sistemes radar per l'automoció a la banda W. La primera part d'aquesta tesis consisteix en l'anàlisi d'algunes tecnologies circuitals a freqüències mil•limètriques. S'han presentat els materials més utilitzats a altes freqüències (Polytetrafluoroethylene or Teflon (PTFE), Quartz, Benzocyclobuten polymer (BCB) i Low Temperature Co-fired Ceramic (LTCC)) i s'han comparat en termes de permitivitat i tangent de pèrdues. També s'inclou un estudi de pèrdues a altes freqüències en les principals línies de transmissió (microstrip, stripline i CPW). Finalment, es presenta un resum dels interruptors RF-MEMS i es comparen amb els PIN diodes i els FET. En la segona part, es presenten diferents agrupacions d'antenes amb la capacitat de reconfigurar la polarització i la direcció d'apuntament. S'han dissenyat dos elements base reconfigurables en polarització: CPW Patch antena i 4-Qdime antena. La primera antena consisteix en un element singular amb interruptors RF-MEMS, dissenyada per operar a les bandes Ka i V. La segona antena consisteix en una arquitectura composta on la reconfigurabilitat en polarització s'obté mitjançant variant la fase d'alimentació de cada un dels quatre elements lineals. La fase és controlada mitjançant interruptors RF-MEMS ubicats en la xarxa de distribució. L'antena 4-Qdime s'ha dissenyat per operar en les bandes V i W. Ambdós elements base s'han utilitzat posteriorment pel disseny de dues agrupacions d'antenes amb capacitat de reconfigurar l'apuntament del feix principal. La reconfigurabilitat es dur a terme utilitzant desfasadors de fase d'1 bit. La part final de la tesis es centra en les toleràncies de fabricació i en els processo de microfabricació d'agrupacions d'antenes mil•limètriques. Les toleràncies de fabricació s'han estudiat en funció dels error d'amplitud i fase en cada element de l'agrupació, fixant-se en les pèrdues de guany, error d'apuntament, error en l'amplada de feix, errors en el nivell de lòbul secundari i en l'error en la relació axial. El procés de microfabricació de les diferents antenes dissenyades es presenta en detall. Els dissenys de l'antena CPW Patch reconfigurable en polarització i apuntament operant a les bandes Ka i V, s'han fabricat en la sala blanca del Cornell NanoScale Science & Technology Facility (CNF). Posteriorment, s'han caracteritzat l'aïllament i el temps de resposta dels interruptors RF-MEMS, i finalment, el coeficient de reflexió, el diagrama de radiació i la relació axial s'han mesurat a les bandes Ka i V per les antenes configurades en polarització lineal (LP) i circular (CP). / Telecommunication services and radar systems are migrating to Millimeter-wave (MMW) frequencies, where wider bandwidths are available. Such migration requires the use of different technologies with the capability to operate at the MMW frequency band (30 to 300GHz), and more specifically at Ka- (26.5 to 40GHz), V- (50 to 75GHz) and W-band (75 to 110GHz). For many applications and more concretely those where the antenna is part of a mobile device, it is targeted the use of planar antennas for their low profile and low fabrication cost. A wide variety of requirements is translated into a reconfiguration capability and low losses within each application frequency bandwidth. To deal with the mentioned challenges, the MMW antenna dimensions, together with the materials, fabrication tolerances and reconfigurability capability lead to microfabrication processes. The aim of this thesis is the analysis of the mentioned concepts, materials, transmission lines geometries and switches in the MMW frequencies context and their final application in antenna designs compatible with microfabrication. Finally, specific designs are presented as a demonstration for three MMW applications: Satellite Communication Systems (SCS) at Ka-band, Wireless Personal Area Network (WPAN) at V-band and Automotive Radar at W-band. The first part of this thesis consist to analyze some MMW circuit technologies. The four most used materials at MMW frequencies (Polytetrafluoroethylene or Teflon (PTFE), Quartz, Benzocyclobuten polymer (BCB) and Low Temperature Co-fired Ceramic (LTCC)) have been presented and compared in terms of permittivity (εr) and loss tangent (tanδ). An study of the main transmission lines attenuation (microstrip, stripline and CPW) at high frequencies is included. Finally, an overview of the RF-MEMS switches is presented in comparison with PIN diodes and FETS switches. The second part presents different polarization and beam pointing reconfigurable array antennas. Two polarization-reconfigurable base-elements have been designed: CPW Patch antenna and 4-Qdime antenna. The first consists of a single reconfigurable element with integrated RF-MEMS switches, designed to operate at Ka- and V-band. The second antenna presented in this thesis has a composed architecture where the polarization reconfigurability is obtained by switching the phase feeding for each of the four linear polarized elements in the feed network with RF-MEMS switches. The 4-Qdime antenna has been designed to operate at V- and W-band. The two base-elements have been used to design two beam pointing reconfigurable antenna arrays. Using phased array techniques, beamsteering is computed and implemented with 1-bit discrete phase-shifter. The final part of the thesis is focused into the fabrication tolerances and microfabrication process of Millimeter-wave antenna arrays. The fabrication tolerances have been studied as a function of the amplitude and phase errors presented at each elements array, focusing on the gain loss, beam pointing error, Half-Power Beamwidth (HPBW) error, sidelobe level error and axial ratio error. The microfabrication process for the designed antennas is presented in detail. Polarization- and pointing- reconfigurable CPW Patch antenna operating at Ka- and V- band have been fabricated in a clean-room facility at Cornell NanoScale Science & Technology Facility (CNF). The RF-MEMS switches isolation and time response have been characterized. Finally, the reflection coefficient, radiation pattern and axial ratio have been measured at Ka- and V-band for the fabricated antennas configured in Linear Polarization (LP) and Circular Polarization (CP).

Beam scanning Microstrip (BSMS) antenna is designed to work at center frequency of 10 GHz for using in the scanning applications of 9 GHz to 11 GHz band. The design parameters are defined and by using an Electromagnetic Simulation software program, the parameters are optimized. A Beam Scanning Microstrip Antenna is produced as a prototype and the measurement&rsquo / s results are compared with theoretical results. In conclusion, the values of deviation between theoretical and experimental results are discussed.

Cylindrically conformal microstrip antennas are investigated. Two different structures, namely proximity coupled and E-shaped microstrip antennas are analyzed and information about the design parameters is obtained by means of parametric study. With these structures, cylindrical arrays, having omnidirectional radiation in the circumferential plane of the cylinder, are designed. Proximity coupled cylindrical arrays operate in the 2.3-2.4 GHz aeronautical telemetry band with approximately 4% bandwidth. On the other hand, more than 30% bandwidth is obtained by E-Shaped cylindrical array antenna structure, which also includes the commercial telemetry band. In order to verify the simulation method, a fabricated antenna in literature is simulated and acceptable agreement with simulation and fabrication results obtained.

The master s thesis deals with the design of the beamsteering antenna. Methods of the beamsteering and the final antenna design are described. This antenna operates in the ISM band with the central frequency of 5,8 GHz. The antenna is designed in the CST Studio Suite 2020. Butler matrix was designed as a feed network implemented as substrate integrated waveguide. An array of patch antennas was used for radiation.

This diploma thesis deals with optimization of planar antennas on the Electromagnetic Bandgap (EBG) substrates by the help of Ant Colony Optimization (ACO). This method is based on the communications mechanisms of a real ant colony. Firstly, the working principle of the planar antennas and the theory of the Ant Colony Optimization are analyzed. Next, the description of the working principle of the Electromagnetic Bandgap and generally physical phenomena accompanying electromagnetic waves propagation in a periodic medium are given. In the second part of this thesis, the ACO was implemented into the VBA language, and was applied to two models of planar antennas. These models were created in the CST Microwave Studio. After an optimization of the antennas the results were evaluated, and the optimization of one of the antennas was compared to the optimization methods in CST Microwave Studio. Then, the standard substrate of the second model was replaced by the EBG substrate, and the results were confronted. Two types of EBG lattice were used. The design procedure of the square lattice was described, and the dispersion diagram was created in the CST Microwave Studio. In the final part of thesis, the verification of the results was carried out in Ansoft HFSS, and the results from both simulation programs were compared to each other.

The goal of this thesis is design and build rectangular patch antenna for 60 GHz band, matched to 50 Ohms. First section described general knowledges about microstrips antennas and technologies for 60 GHz band. Second section introduced rectangular patch antenna feeded by miscrostrip line matched by quarter wave transformer on CuClad 217 substrate. Third section introduced two structural modification of rectangular patch antenna and measurements of return loss |S11|.

La Transformation d’Espace appelée aussi Transformation Optique (TO) est un outil de conception électromagnétique puissant qui a permis la conception de nouveaux dispositifs tels que la célèbre “cape d'invisibilité”. Cette thèse s’inscrit dans la continuité directe de celle de M.D. Clemente Arenas (Application de la transformation d'espace à la conception d'antennes à diagramme de rayonnement contrôlé, 2014) et porte sur l’utilisation de la TO pour modifier drastiquement le rayonnement d’une antenne patch. Ces fortes modifications du rayonnement sont habituellement obtenues avec l’aide d’un superstrat encombrant et constitué de matériaux ayant une perméabilité et permittivité exotiques (métamatériaux). L’objectif est donc ici de réduire cet encombrement et de simplifier la réalisation en utilisant des matériaux diélectriques standards. Ainsi, grâce au superstrat développé, une antenne patch ayant un gain réalisé de 7 dB devient une antenne présentant deux lobes dans le plan azimutal de gain réalisé de 3.5 dB. Le superstrat, d’épaisseur 0.12λ, est conçu à l’aide de deux matériaux uniquement : Alumine (εr = 9.9) et Fullcure (εr = 2.8), alors que le profil initial comporte une permittivité variant entre 1 et 15 et une perméabilité entre 0.3 et 3. Divers degrés de libertés dans la conception permettent d'adapter notre solution pour concevoir d’autres superstrats avec des fonctionnalités différentes: diagramme ayant une ouverture de plus de 180° dans un plan, diagramme end-fire, etc. Les applications visées sont notamment celles de l’aéronautique pour lesquelles il existe aujourd’hui sur les aéronefs plusieurs dizaines d’antennes pour assurer toutes les liaisons nécessaires aux communications, à l’identification, au positionnement, etc. La géométrie du porteur conduit alors à utiliser plusieurs antennes protubérantes pour remplir cette mission. Cependant pour un avion, ces excroissances contribuent à dégrader l’aérodynamisme de l’appareil ce qui se traduit par une consommation plus importante. Le but est donc de proposer des solutions antennaires à rayonnement nonconventionnel et non protubérante compatible avec une intégration sur dérive ou fuselage. Le concept est validé à l'aide d'une maquette réalisée avec une imprimante 3D et avec le soutien d’Airbus Group Innovations. / Transformation Optics (TO) is a powerful electromagnetic design tool that enables the design of new devices such as the famous "invisibility cloak". This thesis is in direct continuation of that of M.D. Clemente Arenas (Application de la transformation d'espace à la conception d'antennes à diagramme de rayonnement contrôlé, 2014) and focuses on the use of the TO to drastically change radiation of a patch antenna. These sharp changes in radiation pattern are usually obtained using bulky superstrates made of metamaterials having exotic permeability and permittivity values. The objective of this thesis is to reduce the thickness of the superstrate and simplify the fabrication by enabling the use of standard dielectric materials. Thus, a patch antenna with realized gain of 7 dB is transformed, with the help of proposed superstrate, into an antenna having two lobes in the azimuth plane withrealized gain of 3.5 dB. The 0.12λ thick superstrate is designed using two standard dielectric materials only: Alumina (εr = 9.9) and FullCure (εr = 2.8), whereas the previous solution had variation in permittivity between 1 and 15 and in permeability between 0.3 and 3. Various degrees of freedom in the design allow adapting this solution to develop new superstrates for other applications: radiation pattern with HPBW greater than 180 ° in one plane, end-fire radiation pattern, etc. Target applications include those of aeronautics. Today, dozens of antennas on an aircraft are required to ensure the necessary communications links, identification, positioning and other purposes. The structure of the aircraft necessitates use multiple antennas to fulfill this mission, which are fixed and protrude on fuselage or wings. However, for an aircraft, these protuberances contribute to the aerodynamic drag, which results in higher fuel consumption. Therefore, the objective is to propose conformal antenna solutions with unconventional radiation pattern, which can be eventually integrated on fuselage or rudder. The concept is validated using a model made with a 3D printer and with the support of Airbus Group Innovations

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