Applications of Microwave Antenna Array for Wireless Power Transmission and Radar Imaging in Complex Environment

Thesis (Ph.D.)--University of Washington, 2016-08

Design and implementation of wideband baluns for Archimedean spiral antennas

The demand for high-speed data services for portable device has become a driving force for development of advanced broadband access technologies. Despite recent advances in broadband wireless technologies, there remain a number of critical issues to be resolved. One of the major concerns is the implementation of compact antennas that can operate in a wide frequency band. Spiral antenna has been used extensively for broadband applications due to its planar structure, wide bandwidth characteristics and circular polarisation. However, the practical implementation of spiral antennas is challenged by its high input characteristic impedance, relatively low gain and the need for balanced feeding structures. Further development of wideband balanced feeding structures for spiral antennas with matching impedance capabilities remain a need. This thesis proposes three wideband feeding systems for spiral antennas which are compatible with wideband array antenna geometries. First, a novel tapered geometry is proposed for a symmetric coplanar waveguide (CPW) to coplanar strip line (CPS) wideband balun. This balun can achieve the unbalanced to balanced transformation while matching the high input impedance of the antenna to a reference impedance of 50 . The discontinuity between CPW and CPS is accommodated by using a radial stub and bond wires. The bandwidth of the balun is improved by appropriately tapering the CPW line instead of using a stepped impedance transformer. Next, the tapered design is applied to an asymmetric CPW to propose a novel asymmetric CPW to CPS wideband balun. The use of asymmetric CPW does away with the discontinuities between CPW and CPS without having to use a radial stub or bond wires. Finally, a tapered microstrip line to parallel striplines balun is proposed. The balun consists of two sections. One section is the parallel striplines which are connected to the antenna, with the impedance of balanced line equal to the antenna input impedance. The other section consists of a microstrip line where the width of the ground plane is gradually reduced to eventually resemble a parallel stripline. The taper accomplishes the mode and impedance transformation. This balun has significantly improved bandwidth characteristics. Characteristics of proposed feeding structures are measured in a back-to-back configuration and compared to simulated results. The simulated and measured results show the tapered microstrip to parallel striplines balun to have more than three octaves of bandwidth. The tapered microstrip line to parallel striplines balun is integrated with a single Archimedean spiral antenna and with an array of spiral antennas. The performance of the integrated structures is simulated with the aid of electromagnetic simulation software, and results are compared to measurements. The back-to-back microstrip to parallel strip balun has a return loss of better than 10 dB over a wide bandwidth from 1.75 to 15 GHz. The performance of the microstrip to parallel strip balun was validated with the spiral antennas. The results show the balun to be an effective mean of feeding network with a low profile and wide bandwidth (2.5 to 15 GHz) for balanced spiral antennas.

Design optimisation of ring elements for broadband reflectarray antennas

Plane wave scattering from a flat surface consisting of two periodic arrays of ring elements printed on a grounded dielectric sheet is investigated. It is shown that the reflection phase variation as a function of ring diameter is controlled by the difference in the centre resonant frequency of the two arrays. Simulated and measured results at X-band demonstrate that this parameter can be used to reduce the gradient and improve the linearity of the reflection phase versus ring size slope. These are necessary conditions for the re-radiating elements to maximise the bandwidth of a microstrip reflectarray antenna. The scattering properties of a conventional dual resonant multilayer structure and an array of concentric rings printed on a metal backed dielectric substrate are compared and the trade-off in performance is discussed.

Low-profile resonant cavity antenna with artificial magnetic conductor ground plane

A planar artificial magnetic conductor (AMC) ground plane is proposed as a means to reduce the profile of a highly directive resonant cavity antenna. The structure is formed by a printed microstrip patch antenna and a superimposed partially reflective surface. The antenna profile is reduced to approximately half by virtue of employing the AMC ground plane. A ray theory model is used to qualitatively describe the functioning of the antenna and theoretically predict the existence of quarter wavelength resonant cavities.

Retrodirective Terminal Antenna for Satellite and Terrestrial Mobile Communications

The potential for implementation of retrodirective arrays as antenna terminals for future integrated satellite and terrestrial mobile communications is discussed in this paper. Particularly, in the context of the Inmarsat L-band system we address the issues related to array antenna element capacity to produce high-quality circular polarized radiation pattern over large angles of arrival. We also discuss circuitry reduction methodologies and their effect on retrodirected beam characteristics. The possibility of circular polarization modulation of the re-transmit signal is also discussed.

A new broadband circular patch antenna

A simple technique to improve the impedance bandwidth of a circular microstrip patch antenna using two sectorial slots is proposed. Using this design more than 5% impedance bandwidth is obtained. The added advantage of this new antenna is that it can be fed by a 50- microstrip line

A New Broadband Circular Patch Antenna

A simple technique to improve the impedance bandwidth of a circular microstrip patch antenna using two sectorial slots is proposed. Using this design more than 5% impedance bandwidth is obtained. The added advantage of this new antenna is that it can be fed by a 50 microstrip line.

INVESTIGATIONS ON SLOT-LOADED SQUARE MICROSTRIP PATCH ANTENNAS FOR COMPACT DUAL FREQUENCY DUAL POLARIZED OPERATIONS

The thesis is the outcome of the experimental and theoretical investigations carried out on a novel slotted microstrip antenna.The antenna excites two resonance frequencies and provides orthogonal polarization. The radiation characteristics of the antenna are studied in detail. The antenna design is optimized using IE3D electromagnetic simulation tool. The frequency-Difference Time-Domain (FDTD) method is employed for the analysis of the antenna.The antenna can be used for personal and satellite communication applications.

Design and Development of re configurable compact cross patch antenna for switchable polarization

Antennas are necessary and vital components of communication and radar systems, but sometimes their inability to adjust to new operating scenarios can limit system performance. Reconfigurable antennas can adjust with changing system requirements or environmental conditions and provide additional levels of functionality that may result in wider instantaneous frequency bandwidths, more extensive scan volumes, and radiation patterns with more desirable side lobe distributions. Their agility and diversity created new horizons for different types of applications especially in cognitive radio, Multiple Input Multiple Output Systems, satellites and many other applications. Reconfigurable antennas satisfy the requirements for increased functionality, such as direction finding, beam steering, radar, control and command, within a confined volume. The intelligence associated with the reconfigurable antennas revolved around switching mechanisms utilized. In the present work, we have investigated frequency reconfigurable polarization diversity antennas using two methods: 1. By using low-loss, high-isolation switches such as PIN diode, the antenna can be structurally reconfigured to maintain the elements near their resonant dimensions for different frequency bands and/or polarization. 2. Secondly, the incorporation of variable capacitors or varactors, to overcome many problems faced in using switches and their biasing. The performances of these designs have been studied using standard simulation tools used in industry/academia and they have been experimentally verified. Antenna design guidelines are also deduced by accounting the resonances. One of the major contributions of the thesis lies in the analysis of the designed antennas using FDTD based numerical computation to validate their performance.

Investigations on the Radiation Characteristics of Broadband Strip Loaded Slotted Microstrip Antennas

With the recent progress and rapid increase in mobile terminals, the design of antennas for small mobile terminals is acquiring great importance. In view of this situation, several design concepts are already been addressed by the scientists and engineers. Compactness and efficiency are the major criteria for mobile terminal antennas. The challenging task of the microwave scientists and engineers is to device compact printed radiating systems having broadband behavior, together with good efficiency. Printed antenna technology has received popularity among antenna scientists after the introduction of microstrip antenna in 1970s. The successors in this kind such as printed monopoles and planar inverted F are also equally important. Scientists and Engineers are trying to explore this technology as a viable coast effective solution for forthcoming microwave revolution. The transmission line perspectives of antennas are very interesting. The concept behind any electromagnetic radiator is simple. Any electromagnetic system with a discontinuity is radiating electromagnetic energy. The size, shape and the orientation of the discontinuities controls the radiation characteristics of the system such as radiation pattern, gain, polarization etc. It can be either resonant or non resonant structure. Microstrip antennas are suitable for wireless applications due to their low cost, high gain and ease of fabrication. But the major disadvantage of micro strip antennas is their inherent narrow bandwidth. A lot of techniques are introduced by the researchers all over the world to enhance the bandwidth of micro strip patch antennas. The thesis addresses an attempt to enhance the bandwidth of micro strip patch antennas by incorporating impedance matching strip as a part of the micro strip patch antenna. The first part of the thesis deals with the broadband operation of the tilted square slot and polygonal slot loaded square micro strip patch antennas. The resonant mechanisms are clearly mentioned using the simulation and experimental studies. The bandwidth of the polygonal slotted broadband patch antenna is again enhanced by implementing an Lstrip feed mechanism. In the second major part of the thesis, a novel gain enhancement technique for single band and broadband square micro strip patch antennas is achieved by implementing offset stacked configurations.

Electromagnetically Coupled Dual Port, Dual Band, Octagonal Patch Antenna

In this paper, a dual port, dual frequency, dual polarized, octagonal shaped Microstrip patch antenna, suitable for GPS applications is discussed experimentally and theoretically. The proposed antenna configuration is characterized by good impedance bandwidth, gain, isolation between two ports and broad radiation patterns

Parametric study of retangular patch antenna using denim textile material

—This paper presents a textile patch antenna designed for WBAN applications at 2.45 GHz ISM band. The antenna uses denim as substrate and conductive fabric for the ground plane and radiator layers. The main purpose of this paper is to analyze the influence of typical deviation of denim properties and patch radiator dimensions on the performance of the antenna. The parameters considered in the analysis are the relative permittivity and thickness of denim and the width and length of the rectangular patch radiator. The dependence of the central operation frequency of the antenna on those parameters was studied using the antenna reflection coefficient obtained from EM simulations. Rules of thumb for one-shot design were derived and applied to design a rectangular patch antenna. An antenna prototype was fabricated and measured, demonstrating a 10 dB impedance band of 4.8 % centered at 2.45 GHz, in good agreement with simulated results

Aspects of a phased array radar feed and bias network design

Radar technologies have been developed to improve the efficiency when detecting targets. Radar is a system composed by several devices connected and working together. Depending on the type of radar, the improvements are focused on different functionalities of the radar. One of the most important devices composing a radar is the antenna, that sends the radio-frequency signal to the space in order to detect targets. This project is focused on a specific type of radar called phased array radar. This type of radar is characterized by its antenna, which consist on a linear array of radiating elements, in this particular case, eight dipoles working at the frequency band S. The main advantage introduced by the phased array antenna is that using the fundamentals of arrays, the directivity of the antenna can change by shifting the phase of the signal at the input of each radiating element. This can be done using phase shifters. Phase shifter consists on a device which produces a phase shift in the radio-frequency input signal depending on a control DC voltage. Using a phased array antenna allows changing the directivity of the antenna without a mechanical rotating system. The objective of this project is to design the feed network and the bias network of the phased antenna. The feed network consists on a parallel-fed network composed by power dividers that sends the radio-frequency signal from the source to each radiating element of the antenna. The bias network consists on a system that generates the control DC voltages supplied to the phase shifters in order to change the directivity. The architecture of the bias network is composed by a software, implemented in Matlab and run in a laptop which is connected to a micro-controller by a serial communication port. The software calculates the control DC voltages needed to obtain a determined directivity or scan angle. These values are sent by the serial communication port to the micro-controller as data. Then the micro-controller generates the desired control DC voltages and supplies them to the phase shifters. In this project two solutions for bias network are designed. Each one is tested and final conclusions are obtained to determine the advantages and disadvantages. Finally a graphic user interface is developed in order to make the system easy to use. RESUMEN. Las tecnologías empleadas por lo dispositivos radar se han ido desarrollando para mejorar su eficiencia y usabilidad. Un radar es un sistema formado por varios subsistemas conectados entre sí. Por lo que dependiendo del tipo de radar las mejoras se centran en los subsistemas correspondientes. Uno de los elementos más importantes de un radar es la antena. Esta se emplea para enviar la señal de radiofrecuencia al espacio y así poder detectar los posibles obstáculos del entorno. Este proyecto se centra en un tipo específico de radar llamado phased array radar. Este tipo de radar se caracteriza por la antena que es un array de antenas, en concreto para este proyecto se trata de un array lineal de ocho dipolos en la banda de frequencia S. El uso de una antena de tipo phased array supone una ventaja importante. Empleando los fundamentos de radiación aplicado a array de antenas se obtiene que la directividad de la antena puede ser modificada. Esto se consigue aplicando distintos desfasajes a la señal de radiofrecuencia que alimenta a cada elemento del array. Para aplicar los desfasajes se emplea un desplazador de fase, este dispositivo aplica una diferencia de fase a su salida con respecto a la señal de entrada dependiendo de una tensión continua de control. Por tanto el empleo de una antena de tipo phased array supone una gran ventaja puesto que no se necesita un sistema de rotación para cambiar la directividad de la antena. El objetivo principal del proyecto consiste en el diseño de la red de alimentación y la red de polarización de la antena de tipo phased array. La red de alimentación consiste en un circuito pasivo que permite alimentar a cada elemento del array con la misma cantidad de señal. Dicha red estará formada por divisores de potencia pasivos y su configuración será en paralelo. Por otro lado la red de polarización consiste en el diseño de un sistema automático que permite cambiar la directividad de la antena. Este sistema consiste en un programa en Matlab que es ejecutado en un ordenador conectado a un micro-controlador mediante una comunicación serie. El funcionamiento se basa en calcular las tensiones continuas de control, que necesitan los desplazadores de fase, mediante un programa en Matlab y enviarlos como datos al micro-controlador. Dicho micro-controlador genera las tensiones de control deseadas y las proporciona a cada desplazador de fase, obteniendo así la directividad deseada. Debido al amplio abanico de posibilidades, se obtienen dos soluciones que son sometidas a pruebas. Se obtienen las ventajas y desventajas de cada una. Finalmente se implementa una interfaz gráfica de usuario con el objetivo de hacer dicho sistema manejable y entendible para cualquier usuario.

Contribución a los arrays de antenas activos en microondas = Contribution to active array antennas at microwave bands

Esta tesis que tiene por título "Contribución a los arrays de antenas activos en banda X", ha sido desarrollada por el estudiante de doctorado Gonzalo Expósito Domínguez, ingeniero de telecomunicación en el Grupo de Radiación del Departamento de Señales, Sistemas y Radiocomunicaciones de la ETSI de Telecomunicación de la Universidad Politécnica de Madrid bajo la dirección de los doctores Manuel Sierra Castañer y José Manuel Fernández González. Esta tesis contiene un profundo estudio del arte en materia de antenas activas en el campo de apuntamiento electrónico. Este estudio comprende desde los fundamentos de este tipo de antenas, problemas de operación y limitaciones hasta los sistemas actuales más avanzados. En ella se identifican las partes críticas en el diseño y posteriormente se llevan a la práctica con el diseño, simulación y construcción de un subarray de una antena integrada en el fuselaje de un avión para comunicaciones multimedia por satélite que funciona en banda X. El prototipo consta de una red de distribución multihaz de banda ancha y una antena planar. El objetivo de esta tesis es el de aplicar nuevas técnicas al diseño de antenas de apuntamiento electrónico. Es por eso que las contribuciones originales son la aplicación de barreras electromagnéticas entre elementos radiantes para reducir los acoplamientos mutuos en arrays de exploración electrónica y el diseño de redes desfasadoras sencillas en las que no son necesarios complejos desfasadores para antenas multihaz. Hasta la fecha, las barreras electromagnéticas, Electronic Band Gap (EBG), se construyen en sustratos de permitividad alta con el fin de aumentar el espacio disponible entre elementos radiantes y reducir el tamaño de estas estructuras. Sin embargo, la utilización de sustratos de alta permitividad aumenta la propagación por ondas de superficie y con ellas el acoplo mutuo. Utilizando sustratos multicapa y colocando la vía de las estructuras en su borde, en vez de en su centro, se consigue reducir el tamaño sin necesidad de usar sustratos de alta permitividad, reducir la eficiencia de radiación de la antena o aumentar la propagación por ondas de superficie. La última parte de la tesis se dedica a las redes conmutadoras y desfasadoras para antenas multihaz. El diseño de las redes de distribución para antenas son una parte crítica ya que se comportan como un atenuador a la entrada de la cadena receptora, modificando en gran medida la figura de ruido del sistema. Las pérdidas de un desfasador digital varían con el desfase introducido, por ese motivo es necesario caracterizar y calibrar los dispositivos correctamente. Los trabajos presentados en este manuscrito constan de un desfasador reflectivo con un conmutador doble serie paralelo para igualar las pérdidas de inserción en los dos estados y también un conmutador de una entrada y dos salidas cuyos puertos están adaptados en todo momento independientemente del camino del conmutador para evitar las reflexiones y fugas entre redes o elementos radiantes. El tomo finaliza con un resumen de las publicaciones en revistas científicas y ponencias en congresos, nacionales e internacionales, el marco de trabajo en el que se ha desarrollado, las colaboraciones que se han realizado y las líneas de investigación futuras. ABSTRACT This thesis was carried out in the Radiation Group of the Signals, Systems and Radiocomunications department of ETSI de Telecomunicación from Technical University of Madrid. Its title is "Contribution to active array antennas at X band" and it is developed by Gonzalo Expósito Domínguez, Electrical Engineer MsC. under the supervision of Prof. Dr. Manuel Sierra Castañer and Dr. José Manuel Fernández González. This thesis is focused on active antennas, specifically multibeam and electronic steering antenas. In the first part of the thesis a thorough description of the state of the art is presented. This study compiles the fundamentals of this antennas, operation problems and limits, up to the breakthrough applications. The critical design problems are described to use them eventually in the design, simulation and prototyping of an airborne steering array antenna for satellite communication at X band. The main objective of this thesis is to apply new techniques to the design of electronically steering antennas. Therefore the new original contributions are the application of Electromagnetic Band Gap materials (EBG) between radiating elements to reduce the mutual coupling when phase shift between elements exist and phase shifting networks where special characteristics are required. So far, the EBG structures have been constructed with high permitivity substrates in order to increase the available space between radiating elements and reduce the size of the structures. However, the surface wave propagation modes are enhanced and therefore the mutual coupling increases when high permitivity substrates are used. By using multilayered substrates and edge location via, the size is reduced meanwhile low permitivity substrates are used without reducing the radiation efficiency or enhancing the surface propagation modes. The last part of the thesis is focused on the phase shifting distribution networks for multibeam antennas. This is a critical part in the antenna design because the insertion loss in the distribution network behaves as an attenuator located in the first place in a receiver chain. The insertion loss will affect directly to the receiver noise figure and the insertion loss in a phase shifter vary with the phase shift. Therefore the devices must be well characterized and calibrated in order to obtain a properly operation. The work developed in this thesis are a reflective phase shifter with a series-shunt switch in order to make symmetrical the insertion loss for the two states and a complex Single Pole Double Through (SPDT) with matched ports in order to reduce the reflections and leakage between feeding networks and radiating elements. The end of this Ph D. dissertation concludes with a summary of the publications in national and international conferences and scientific journals, the collaborations carried out along the thesis and the future research lines.

Analysis and design of reconfigurable multimode multiport microstrip antennas for mimo systems and diversity schemes

Las comunicaciones inalámbricas han transformado profundamente la forma en la que la gente se comunica en el día a día y es, sin lugar a dudas, una de las tecnologías de nuestro tiempo que más rápidamente evoluciona. Este rápido crecimiento implica retos enormes en la tecnología subyacente, debido y entre otros motivos, a la gran demanda de capacidad de los nuevos servicios inalámbricos. Los sistemas Multiple Input Multiple Output (MIMO) han despertado mucho interés como medio de mejorar el rendimiento global del sistema, satisfaciendo de este modo y en cierta medida los nuevo requisitos exigidos. De hecho, el papel relevante de esta tecnología en los actuales esfuerzos de estandarización internacionales pone de manifiesto esta utilidad. Los sistemas MIMO sacan provecho de los grados de libertad espaciales, disponibles a través del entorno multitrayecto, para mejorar el rendimiento de la comunicación con una destacable eficiencia espectral. Con el fin de alcanzar esta mejora en el rendimiento, la diversidad espacial y por diagrama han sido empleadas tradicionalmente para reducir la correlación entre los elementos radiantes, ya que una correlación baja es condición necesaria, si bien no suficiente, para dicha mejora. Tomando como referencia, o punto de partida, las técnicas empleadas para obtener diversidad por diagrama, esta tesis doctoral surge de la búsqueda de la obtención de diversidad por diagrama y/o multiplexación espacial a través del comportamiento multimodal de la antena microstrip, proponiendo para ello un modelo cuasi analítico original para el análisis y diseño de antenas microstrip multipuerto, multimodo y reconfigurables. Este novedoso enfoque en este campo, en vez de recurrir a simulaciones de onda completa por medio de herramientas comerciales tal y como se emplea en las publicaciones existentes, reduce significativamente el esfuerzo global de análisis y diseño, en este último caso por medio de guías de diseño generales. Con el fin de lograr el objetivo planteado y después de una revisión de los principales conceptos de los sistemas MIMO que se emplearán más adelante, se fija la atención en encontrar, implementar y verificar la corrección y exactitud de un modelo analítico que sirva de base sobre la cual añadir las mejoras necesarias para obtener las características buscadas del modelo cuasi analítico propuesto. Posteriormente y partiendo del modelo analítico base seleccionado, se exploran en profundidad y en diferentes entornos multitrayecto, las posibilidades en cuanto a rendimiento se refiere de diversidad por diagrama y multiplexación espacial, proporcionadas por el comportamiento multimodal de las antenas parche microstrip sin cargar. Puesto que cada modo de la cavidad tiene su propia frecuencia de resonancia, es necesario encontrar formas de desplazar la frecuencia de resonancia de cada modo empleado para ubicarlas en la misma banda de frecuencia, manteniendo cada modo al mismo tiempo tan independiente como sea posible. Este objetivo puede lograrse cargando adecuadamente la cavidad con cargas reactivas, o alterando la geometría del parche radiante. Por consiguiente, la atención en este punto se fija en el diseño, implementación y verificación de un modelo cuasi analítico para el análisis de antenas parche microstrip multipuerto, multimodo y cargadas que permita llevar a cabo la tarea indicada, el cuál es una de las contribuciones principales de esta tesis doctoral. Finalmente y basándose en el conocimiento adquirido a través del modelo cuasi analítico, se proporcionan y aplican guías generales para el diseño de antenas microstrip multipuerto, multimodo y reconfigurables para sistemas MIMO, con el fin de mejorar su diversidad por diagrama y/o su capacidad por medio del comportamiento multimodal de las antenas parche microstrip. Se debe destacar que el trabajo presentado en esta tesis doctoral ha dado lugar a una publicación en una revista técnica internacional de un alto factor de impacto. De igual manera, el trabajo también ha sido presentado en algunas de las más importantes conferencias internacionales en el ámbito de las antenas ABSTRACT Wireless communications have deeply transformed the way people communicate on daily basis and it is undoubtedly one of the most rapidly evolving technologies of our time. This fast growing behaviour involves huge challenges on the bearing technology, due to and among others reasons, the high demanding capacity of new wireless services. MIMO systems have given rise to considerable interest as a means to enhance the overall system performance, thus satisfying somehow the new demanding requirements. Indeed, the significant role of this technology on current international standardization efforts, highlights this usefulness. MIMO systems make profit from the spatial degrees of freedom available through the multipath scenario to improve the communication performance with a remarkable spectral efficiency. In order to achieve this performance improvement, spatial and pattern diversity have been traditionally used to decrease the correlation between antenna elements, as low correlation is a necessary but not sufficient condition. Taking as a reference, or starting point, the techniques used to achieve pattern diversity, this Philosophiae Doctor (Ph.D.) arises from the pursuit of obtaining pattern diversity and/or spatial multiplexing capabilities through the multimode microstrip behaviour, thus proposing a novel quasi analytical model for the analysis and design of reconfigurable multimode multiport microstrip antennas. This innovative approach on this field, instead of resorting to full-wave simulations through commercial tools as done in the available publications, significantly reduces the overall analysis and design effort, in this last case through comprehensive design guidelines. In order to achieve this goal and after a review of the main concepts of MIMO systems which will be followed used, the spotlight is fixed on finding, implementing and verifying the correctness and accuracy of a base quasi analytical model over which add the necessary enhancements to obtain the sought features of the quasi analytical model proposed. Afterwards and starting from the base quasi analytical model selected, the pattern diversity and spatial multiplexing performance capabilities provided by the multimode behaviour of unloaded microstrip patch antennas under different multipath environments are fully explored. As each cavity mode has its own resonant frequency, it is required to find ways to displace the resonant frequency of each used mode to place them at the same frequency band while keeping each mode as independent as possible. This objective can be accomplished with an appropriate loading of the cavity with reactive loads, or through the alteration of the geometry of the radiation patch. Thus, the focus is set at this point on the design, implementation and verification of a quasi analytical model for the analysis of loaded multimode multiport microstrip patch antennas to carry out the aforementioned task, which is one of the main contributions of this Ph.D. Finally and based on the knowledge acquired through the quasi analytical model, comprehensive guidelines to design reconfigurable multimode MIMO microstrip antennas to improve the spatial multiplexing and/or diversity system performance by means of the multimode microstrip patch antenna behaviour are given and applied. It shall be highlighted that the work presented in this Ph.D. has given rise to a publication in an international technical journal of high impact factor. Moreover, the work has also been presented at some of the most important international conferences in antenna area.