Analysis and synthesis of leaky-wave devices in planar technology

[ESP] ] El trabajo llevado a cabo durante la realización de esta tesis doctoral, se ha centrado en el análisis y síntesis de dispositivos de microondas en tecnología planar. En concreto, se han estudiado diferentes tipos de dispositivos basados en radiación por ondas de fuga "leaky waves", en los cuales las propiedades de radiación están determinadas por la constante de fase del modo "leaky" que es el que determina el ángulo de apuntamiento y por la tasa de radiación que es la que determina la intensidad de los campos radiados. De esta manera, controlando en amplitud y fase el modo "leaky" se puede obtener un control efectivo sobre el diagrama de radiación del dispositivo. Además, con el objetivo de poder obtener de una manera más eficiente las características de propagación de los modos de fuga "leaky" en función de los principales parámetros geométricos de la estructura, se han desarrollado diversas herramientas de análisis modal basadas en la técnica de resonancia transversa de la estructura. La capacidad para obtener un control simultáneo de la constante de propagación compleja del modo "leaky", ha sido demostrada mediante el diseño y fabricación de varios tipos de antena "leaky wave" (LWA) y de otros dispositivos como multiplexores y sistemas de enfoque en campo cercano. Para ello, se ha utilizado la tecnología planar de guía de onda integrada en sustrato (susbstrate integrated waveguide, SIW). Esta recientemente desarrollada tecnología, permite diseñar dispositivos de microondas basados en tecnología clásica de guía de ondas con sistemas de fabricación estándar usados en tecnología de circuitos impresos (printed circuit board, PCB). De esta forma, se pueden integrar en un mismo sustrato muchas de las diferentes partes que forman un sistema de comunicaciones, mejorando así su robustez y compactibilidad, además de reducir el coste y de contar con menores pérdidas que otras tecnologías planares como la microstrip. [ENG] The work developed along this doctoral thesis has been focused on the analysis and synthesis of microwave devices in planar technology. In particular, several types of devices based on the radiation mechanism of leaky waves have been studied. Typically, the radiation properties in leaky-wave devices are determined by the complex propagation constant of the leaky mode, wherein the phase constant is responsible for the pointing angle and the leakage rate for the intensity of the radiated fields. In this manner, by controlling both amplitude and phase of the leaky mode, an effective control over the device's radiation diagram can be obtained. Moreover, with the purpose of efficiently obtaining the leaky mode's radiation properties as function of the main geometrical parameters of the structure, several modal tools based on the transverse resonance analysis of the structure have been performed. In order to demonstrate this simultaneous control over the complex propagation constant in planar technology, several types of leaky-wave devices, including antennas (LWAs), multiplexors and near-field focusing systems, have been designed and manufactured in the technology of substrate integrated waveguide (SIW). This recently proposed technology, allows the design of devices based on classical waveguide technology with standard manufacturing techniques used for printed circuit board (PCB) designs. In this way, most of the parts that form a communication system can be integrated into a single substrate, thus reducing its cost and providing a more robust and compact device, which has less losses compared to other planar technologies such as the microstrip.Universidad Politécnica de Cartagen

Analytical Design Procedures for the Odd Mode of Ridge Gap Waveguide Devices and Antennas

The millimeter-wave (mm-wave) band has attracted attention due to its wideband characteristics that make it able to support multi-gigabit per second data rate. Nevertheless, the performance of mm-wave wireless communication systems is restricted due to attenuation loss. Design of mm-wave components and antennas is rapidly growing with the current evolution in the wireless communication systems. However, the traditional waveguide structures such as microstrip, coplanar, substrate integrated waveguide, and rectangular waveguide either suffer from high losses or difficulty in manufacturing at mm-wave band. The ridge gap waveguide (RGW) technology is considered as a promising waveguide technology for the mm-wave band. RGW technology overcomes the conventional guiding structure problems as the wave propagates in an air gap region which eliminates the dielectric loss. Moreover, RGW does not need any electrical contacts, unlike traditional rectangular waveguides. Also, the RGW can be implemented in the printed form (PRGW) for easy integration with other planer system components. In this thesis, the use of the odd mode (TE10 (RGW)) RGW to design mm-wave components and antennas is presented. First, a systematic design methodology for the RGW using hybrid PEC/PMC waveguide approximation is presented. This reduces the design time using full wave simulators. The concept has been verified by simulation and experimental measurements. Second, two different methods to excite the odd mode in RGW are studied and investigated. In the first method, a planar L-shape RGW is used where less than -10 dB reflection coefficient is achieved, from 28 to 36 GHz, and more than 93% of the input power has been converted into the odd mode at the output port. The second method uses a magic tee with a shorted sum port and provides a wideband pure odd mode at the output port with reflection coefficient less than -10 dB from 28 GHz to 39 GHz. Other mm-wave components based on odd mode TE10 RGW are designed and presented including a Y-junction power divider and 3 dB forward coupler are designed for the first time in RGW technology. The Y-junction has a wideband matching from 28 to 34 GHz with a reflection coefficient less than -15 dB and the transmission output levels are about -3.3 dB. The usefulness of the odd mode RGW lies in the ability to increase the channel bandwidth that has been achieved by designing a dual-mode RGW. A magic tee is used to simultaneously excite the fundamental mode Q-TEM and the odd mode TE10 (RGW) on the ridgeline. The proposed dual-mode RGW performance is verified through simulation and measurement of a back-to-back configuration. The proposed design achieves a matching level less than -10 dB for the two modes over the frequency range from 29 GHz to 34.5 GHz with isolation better than 23 dB. The dual-mode RGW is then used to feed a reconfigurable Vivaldi horn antenna where two different radiation patterns can be obtained depending on the excited mode. The Q-TEM generates a single beam pattern, while the odd mode TE10 (RGW) generates a dual-beam pattern. The maximum gain for the single beam radiation is 12.1 dBi, while it is 10.43 dBi for the dual-beam pattern. The bandwidth of the dual-mode antenna is 25% at 32 GHz with impedance matching less than -10 dB and isolation better than 20 dB. Finally, several antennas are presented in this thesis based on the odd mode RGW. A novel differential feeding cavity antenna using the odd mode of RGW is presented. The measured results show good performance in terms of gain, bandwidth, sidelobe level, and cross-polarization. The maximum gain is 16.5 dBi, and the sidelobe level is -17 dB and -13.8 dB, for the E-plane and H-plane, respectively. Moreover, the proposed antenna has low cross-polarization levels of -35 dB in the E-plane and -27 dB in the H-plane. In addition, two 2x1 linear frequency scanning array antennas are designed and implemented using the proposed Y-junction to generate single beam and dual-beam patterns. The beam scan is from -11(degree) to -40(degree) at 28 GHz and 32 GHz, respectively

Analysis and design of hybrid leaky-wave antennas loaded with frequency selective surfaces

[SPA] En esta tesis se propone una nueva antena de tipo Leaky-Wave (Leaky Wave Antenna, LWA). Estas antenas han recibido mucha atención en las últimas décadas por ser altamente directivas. En concreto, constituyen una solución especialmente atractiva para aplicaciones que requieran altas prestaciones y precisión, como en sistemas de comunicación por satélite y radar. Concretamente, las LWAs consideradas en esta tesis se basan en la radiación producida por una onda de fuga que se propaga por una cavidad resonante. Estas LWAs se denominan de tipo Fabry-Perot, por su analogía con los interferómetros. En concreto, se propone una nueva antena donde la cavidad Fabry-Perot se crea entre dos superficies selectivas en frecuencia (Frequency Selective Surface, FSS), una situada en la parte superior y que actúa como superficie parcialmente reflectante (Partially Reflective Surface, PRS) y otra situada en la parte inferior actuando como superficie de alta impedancia (High Impedance Surface, HIS). Debido a esta composición, denominamos la antena como PRS-HIS-LWA. Las dos FSS consisten en un sustrato dieléctrico impreso con parches metálicos. La principal ventaja de la nueva antena es que permite controlar las características de su diagrama de radiación de una forma flexible y precisa no conocida hasta la fecha. En el primer capítulo se describe la motivación de esta tesis, los objetivos planteados y se clarifican sus principales contribuciones originales. El segundo capítulo se centra en la caracterización eficiente de las superficies periódicas (FSS) que formarán parte de la PRS-HIS-LWA. Se trata de un paso clave, que permitirá el análisis y diseño de forma eficiente de la antena en su totalidad. Se proponen diversos métodos originales para la caracterización de FSSs, y se demuestra su alta eficiencia y utilidad no sólo en el marco de esta tesis, sino en el estudio de muchos otros dispositivos. En el tercer y cuarto capítulos se realiza el análisis y diseño de PRS-HIS-LWAs, comenzando por el caso de una estructura unidimensional (1D) y pasando después al bidimensional (2D). Ambas estructuras son interesantes desde el punto de vista práctico. Las antenas 1D son útiles para aplicaciones donde sea necesario escanear el punto del espacio hacia el que se dirige la radiación (escaneo del haz). Por otro lado, las 2D poseen la capacidad de apuntar hacia el cenit (broadside) con un lóbulo de radiación tipo lápiz muy directivo. El tercer capítulo de la tesis se centra en el análisis y diseño de PRS-HIS-LWAs 1D y 2D uniformes, es decir, en ellas la geometría de la PRS y la HIS permanece constante a lo largo de toda la antena. Se lleva a cabo el análisis de la PRS-HIS-LWA mediante el uso de una red equivalente transversa (Transverse Equivalent Network, TEN) en la que se incluyen las expresiones presentadas en el capítulo 2. Este análisis posibilita el estudio de la influencia de la geometría de la PRS y la HIS en el comportamiento de la antena. En concreto, se concluye que la PRS controla principalmente la tasa de radiación de la antena (y por lo tanto su ancho de haz) y que la HIS proporciona el control sobre ángulo de apuntamiento. En el capítulo cuarto se realiza la síntesis del diagrama de radiación de la PRS-HIS-LWAs tanto en el caso 1D como 2D. A partir de unos requerimientos del diagrama de radiación (ángulo de apuntamiento, ancho de haz, nivel de lóbulo principal a secundario, eficiencia de radiación, eficiencia de iluminación) se obtiene la tasa de radiación y ángulo de apuntamiento que debe presentar la antena en cada punto de su apertura radiante. Para obtener estas características es necesario utilizar los resultados obtenidos en el capítulo anterior y modular la geometría de la PRS y la HIS a lo largo de la estructura. De este modo se diseñan antenas no uniformes, o también llamadas “taper” donde la geometría de las superficies periódicas se ha modulado para sintetizar un determinado diagrama de radiación. Se propone una técnica sistemática totalmente novedosa para realizar esta síntesis, y se aplica en concreto en el caso de reducción de nivel de lóbulo principal a secundario en una antena 1D y en el caso de optimizar las eficiencias de radiación e iluminación en antenas 2D. En el quinto y último capítulo de esta tesis se presentan las conclusiones obtenidas del trabajo realizado así como las líneas futuras de investigación que sugiere. [ENG] This thesis proposes a new type antenna Leaky-Wave (Leaky Wave Antenna, LWA). These antennas have received much attention in the past decades to be highly directives. In particular, constitute an especially attractive solution for applications requiring high performance and precision, as in satellite communication systems and radar. Specifically, the Lwas considered in this thesis are based on the radiation produced by a leakage wave that propagates through a resonant cavity. These are referred Lwas Fabry-Perot type, by analogy with the interferometers. Specifically, it proposes a new antenna where Fabry-Perot cavity is created between two frequency selective surfaces (Frequency Selective Surface, HSS), one located at the top surface and serving as partially reflective (partially reflective surface, PRS) and one located on the bottom surface acting as a high impedance (High Impedance Surface, HIS). Because of this composition, called the antenna as PRS-HIS-LWA. The two FSS consist of a dielectric substrate with printed metallic patches. The main advantage of the new antenna is that it allows the characteristics of the radiation pattern of a flexible and precise unknown to date. The first chapter describes the motivation of this thesis, the objectives and clarified its main original contributions. The second chapter focuses on the efficient characterization of regular surfaces (FSS) that form part of the PRS-HIS-LWA. This is a key step that will allow the analysis and design of the antenna efficiently as a whole. Several methods are proposed to characterize original FSSS, and demonstrated its high efficiency and usefulness not only in the context of this thesis, but in the study of many other devices. In the third and fourth chapters of the study design and analysis of PRS-HIS-lwas, starting with the case of a one-dimensional structure (1D) and then moving to two-dimensional (2D). Both structures are interesting from a practical standpoint. 1D antennas are useful for applications where it is necessary to scan the space to the point that directs radiation (beam scanning). On the other hand, possess the ability 2D point toward the zenith (broadside) with a radiation lobe of highly directive pencil type. The third chapter of the thesis focuses on the analysis and design of PRS-HIS-1D and 2D Lwas uniform, ie, including the geometry of the PRS and HIS remains constant throughout the antenna. It carries out the analysis of the PRS-HIS-LWA using a network equivalent transverse (transverse Equivalent Network, TEN) which includes expressions presented in chapter 2. This analysis allows the study of the influence of the geometry of the PRS and the HIS antenna behavior. Specifically, it is concluded that the PRS mainly controls the rate of radiation of the antenna (and therefore its beamwidth) and which provides control over HIS pointing angle. The fourth chapter synthesis is performed radiation diagram of the PRS-HIS-Lwas both 1D and 2D case. From a radiation pattern requirements (pointing angle, beam width, main lobe level of secondary radiation efficiency, illumination efficiency) is obtained radiation rate and pointing angle of the antenna to be present in each radiant opening point. To obtain these characteristics it is necessary to use the results obtained in the previous chapter modular geometry HIS PRS and along the structure. Thus antennas are designed uniform, or so-called "taper" where the periodic surface geometry has been modulated to synthesize a particular radiation pattern. It proposes a completely novel technique for performing systematic this synthesis, and in particular applies in the case of reduction of main lobe level at an antenna side and in the case 1D optimize efficiencies in radiation and illumination 2D antennas. In the fifth and final chapter of this thesis presents the conclusions of the work and future lines of research that suggests.Universidad Politécnica de Cartagen

Hybrid integration of synthesized dielectric image waveguides in substrate integrated circuit technology and its millimeter wave applications

Analysis, design, and fabrication of the SIIG -- Mode excitation in the SIIG -- Integrated dielectric antennas -- SIIG bends and power splitting/combining -- The SIIG in the context of substrate integrated circuits

Design of Square Patch Microstrip Antenna for Circular Polarization Using IE3D Software

Communication between humans was first by sound through voice. With the desire for slightly more distance communication came, devices such as drums, then, visual methods such as signal flags and smoke signals were used. These optical communication devices, of course, utilized the light portion of the electromagnetic spectrum. It has been only very recent in human history that the electromagnetic spectrum, outside the visible region, has been employed for communication, through the use of radio. One of humankind’s greatest natural resources is the electromagnetic spectrum and the antenna has been instrumental in harnessing this resource.The thesis provides a detailed study of how to design and fabricate a probe-fed Square Microstrip Patch Antenna using IE3D software and study the effect of antenna dimensions Length (L), and substrate parameters relative Dielectric constant (εr), substrate thickness (t) on the Radiation parameters of Bandwidth and Beam-width

Printed circuit metasurfaces for millimeter wave applications

Metasurfaces are artificial composite materials with subwavelength inclusions which have been shown to enable very versatile manipulation of electromagnetic waves. Especially at microwave frequencies, the concept is widely explored and the scope of previous methods of wavefront manipulation such as frequency selective surfaces and leaky-wave antennas has been largely extended. Emerging applications like next generation wireless communication and radar sensing could benefit from novel metasurface-based antennas which have been recently proposed. Although most of these emerging applications use frequencies of operation in the millimeter wave (mm-wave) band, research on metasurfaces in this band is still scarce. Many secondary effects known in the microwave community such as fabrication constraints and material losses are more severe using mm-waves and they significantly hamper the development of efficient devices. The aim of this thesis is to explore design and characterization methods for mm-wave metasurfaces. In particular, this thesis concentrates on planar metasurface architectures that are compatible with established printed circuit board fabrication, which is a requirement for many consumer applications. Causes for significant performance degradation in printed circuit metasurfaces for mm-waves are identified and synthesis techniques with which they can be minimized are proposed. The effectiveness of the proposed synthesis techniques is verified by comprehensive experimental works. Building on these synthesis approaches, two kinds of antenna systems are experimentally demonstrated, based on transmissive metasurfaces and on leaky-wave antennas

Review of Radiation Pattern Control Characteristics for The Microstrip Antenna Based On Electromagnetic Band Gap (EBG)

Radiation Pattern of the antennas is necessary for many applications in the telecommunication field, such as wireless communications and radar. They lessen the interference by channelling the radiation of antenna to the interested direction to achieve the enhancement of spectrum efficiency and multipath propagation reduction that results in the saving of radiation power and the increase in gain. Various techniques have been used to implement beam steering for several years. Electromagnetic band gap (EBG) with unique features helps to prevent/assist the electromagnetic waves propagates in a specific band of frequency for all polarisation states and all incident angles. In this paper, the advantages of the EBG surface wave band gap feature were identified, if it is inserted with microstrip antennas design, which helps to rise the gain of antenna, reduce the back lobe and lessen the mutual coupling in array components. Additionally, more advantages due to the surface waves suppression and the stopping band and passing band of the EBG have been achieved in the beam steering by integrating the single patch microstrip antenna with EBG. Additionally, the new antenna structure based on the combination of the concept of a reconfigurable planar array antenna with the EBG elements requires further research to produce a new radiation pattern control technique

Dielectric Filled Printed Gap Waveguide for Millimeter Wave Applications

As the communication system goes up to millimeter-wave frequencies for high data rate demands, the conventional microstrip line no longer meets the requirements due to its excessive radiation and harmful surface waves, causing unacceptable insertion loss and interference issues. The radiation and surface waves are absent in the stripline. However, its conductor loss becomes worse due to the narrower strip causing by the implemented two ground planes. In addition, any vertical asymmetry in the stripline can generate unwanted higher order waveguide modes that will be able to propagate wherever the ground planes exist. The standard waveguide technology is not suitable for millimeter-wave bands because of the small dimension of the hole, which causes fabrication challenging and high cost. The new technology of gap waveguide (GW) offers a solution to the above problems in current guiding structures. Considerable effort is being made to miniaturize it using the printed circuit technology for low-cost and low-profile applications. The microstrip-ridge GW and the inverted microstrip GW are the two candidates reported previously. However, they come with their own drawbacks. The tiny air gap makes it very sensitive to the outside pressure or the environmental factors. The plated vias in the copper strip and the electroless nickel immersion gold (ENIG) coating on the strip cause substantial attenuation and a frequency shift. In addition, it is challenging to connect to other transmission lines or conventional rectangular waveguides for the integration and measurements. Therefore, one major part of this thesis is to develop innovative GW structures without the formerly mentioned issues to be suitable for millimeter-wave frequencies and easier implementation. Another major part is developing passive components, such as antenna arrays, using the proposed new GW structures. The third part is studying the GW-based PMC packaging for the irregular ground/PEC plane. This will help extend this new packaging technology from the microstrip line circuits to the substrate integrated waveguide (SIW)- or grounded coplanar waveguide (GCPW)-based circuits

Design of Linearly Polarized Rectangular Microstrip Patch Antenna Using IE3D/PSO

In this project, a novel particle swarm optimization method based on IE3D is used to design an Inset Feed Linearly Polarized Rectangular Microstrip Patch Antenna. The aim of the thesis is to Design and fabricate an inset fed rectangular Microstrip Antenna and study the effect of antenna dimensions Length (L) , Width (W) and substrate parameters relative Dielectric constant (εr) , substrate thickness on Radiation parameters of Band width. Low dielectric constant substrates are generally preferred for maximum radiation. The conducting patch can take any shape but rectangular and circular configurations are the most commonly used configuration. Other configurations are complex to analyze and require heavy numerical computations. The length of the antenna is nearly half wavelength in the dielectric; it is a very critical parameter, which governs the resonant frequency of the antenna. In view of design, selection of the patch width and length are the major parameters along with the feed line depth. Desired Patch antenna design is initially simulated by using IE3D simulator. And Patch antenna is realized as per design requirements

Wideband two-dimensional and multiple beam phased arrays and microwave applications using piezoelectric transducers

Modern satellite, wireless communication, and radar systems often demand wideband performance for multi-channel operation and the ability to steer multiple beams for multiple moving targets. This dissertation covers a variety of topics to design low-cost and wideband antenna systems. The main areas of study are microwave devices controlled piezoelectric transducers (PETs) and wideband baluns and balanced microwave circuits using parallel-strip lines. Some focus has also been given to the design of Rotman lens for multiple beam generation and Vivaldi antenna arrays for wideband two-dimensional scanning. The dielectric perturbation technique controlled by PET is introduced to design a wideband phase shifter and a QPSK modulator, and to tune the resonant frequency of a slot dipole. The designed PET-controlled phase shifters are used for beam steering in a dual beam phased array using a bidirectional feeding scheme and a five-beam phased array using a microstrip Rotman lens. Vivaldi-type antennas are commonly used to achieve wideband performance. Very wideband performance can be achieved using an antipodal tapered slot antenna because of its inherent simple wideband transition from microstrip line to parallel-strip line. An antipodal tapered slot antenna and a phased array are designed to span 10 to 35 GHz. In addition, a 4??4 two-dimensional antenna array is designed using wideband antipodal tapered slot antennas, and two sets of PET-controlled phase shifters for E- and H-plane scanning are fabricated to steer the beam. As a microwave system using wideband antenna array, a new low-cost and wideband phased array radar is developed using a modulated pulse over 8 to 20 GHz band. The double-sided parallel-strip line as a balanced line is presented. The parallelstrip line offers much flexibility for microwave circuit designs. This transmission line makes it possible to realize a low impedance line and allows the design of a compact wideband balun and junction. Wideband transitions (or baluns) from parallel-strip line to microstrip line, a typical unbalanced transmission line, are realized to cover several octave bandwidth. Balanced microwave filters and a hybrid coupler are developed using the parallel-strip line