Real-Time Electromagnetic Signal Processing: Principles and Illustrations

Real-time electromagnetic signal processing has recently appeared as a novel signal-processing paradigm to manipulate and control electromagnetic signals in real time directly in the analog domain. This has led to attractive alternatives to conventional digital techniques, which typically suffer from poor performances and high cost at microwave and millimeter wave frequencies. This novel paradigm is based on dispersion-engineered electromagnetic structures, and in this review chapter, two types of structures are presented and discussed in details: phasers and metasurfaces. While phasers are typically group delay engineered to manipulate and rearrange spectral components in the time domain, metasurfaces enhances these functionalities by providing spatial processing in addition to temporal processing. Two kinds of phasers are presented here: static and dynamic all-pass C-section phasers, and all-dielectric metasurface-based spatial phasers. Finally, two applications illustrating real-time signal processing are discussed: 2D beam scanning leaky-wave antenna for high-resolution spectrum analysis and a dispersion code multiple access (DCMA) system

Compact Two-position Phase Shifter

The paper proposes and investigates the topology of a phase shifter based on a directional coupler. The dimensions of such a device are reduced by using artificial transmission lines instead of quarter-wave sections. By connecting several pairs of phase-shifting cells instead of the usual one, it was possible to obtain a phase shifter design with two phase shifts (instead of one) © 2022. Telfor Journal.All Rights Reserved

Microwave Hilbert Transformer and its Applications in Real-time Analog Processing (RAP)

A microwave Hilbert transformer is introduced as a new component for Real-time Analog Processing (RAP). In contrast to its optical counterpart, that resort to optical fiber gratings, this Hilbert transformer is based on the combination of a branch-line coupler and a loop resonator. The transfer function of the transformer is derived using signal flow graphs, and two figures of merits are introduced to effectively characterize the device: the rotated phase and the transition bandwidth. Moreover, a detailed physical explanation of its physical operation is given, using both a steady-state regime perspective and a transient regime perspective. The microwave RAP Hilbert transformer is demonstrated experimentally, and demonstrated in three applications: edge detection, peak suppression and single sideband modulation

Dispersion Based Real-Time Analog Signal Processing (R-ASP) and Application to Wireless Communications

RÉSUMÉ Nous sommes confrontés à une demande explosive de systèmes radio plus rapides, plus fiables et plus écoénergétiques, pour la communication sans fil 5G par exemple. On s’attend à ce que la capacité des données mobiles dépasse 1000 fois ce qu’elle est actuellement dans la prochaine décennie. Un tel volume de données nécessite un grand spectre de bande passante. Aux fréquences radio-fréquences (RF) faibles, le spectre est congestionné par des milliards d’appareils radio. Dans les hautes fréquences, le spectre de bande passante ultra large (UWB) est moins congestionné. Cependant, le traitement d’un tel signal UWB RF pose de grands défis au niveau du traitement du signal (DSP) numérique, qui est habituellement utilisé pour les basses fréquences et les bandes passantes étroites. Les problèmes dont souffre le DSP pour les signaux hautes fréquences sont la limitation de la vitesse, le coût élevé et la forte consommation d’énergie pour la conversion analogique / numérique (ADC). Par conséquent, une technique de traitement en temps réel et purement analogique est souhaitable. En optique, les gens ont traité des signaux RF UWB avec des approches photoniques hyperfréquences en temps réel, mais cela impliquait une conversion électrique / optique coûteuse. Le traitement de signal analogique d’une onde radio en temps réel (R-ASP) est une alternative attrayante et moins exploitée. Le premier chapitre présente l’état de l’art de la technologie R-ASP ainsi que la contribution de la thèse. Le composant au coeur du traitement R-ASP s’appelle "phaseur", un composant qui fournit un retard de groupe spécifié � (!) à une onde radio. Un phaseur, en réponse à un signal d’excitation large bande, réorganise les composants spectraux dans le temps. La façon dont un phaseur réorganise le spectre dépend de la fonction de retard de groupe, � (!). Différentes applications R-ASP peuvent nécessiter des profils de retard de groupe différents. Le chapitre 2 introduit le concept de retard de groupe, présente différentes technologies phaseur, et présente une méthode pour augmenter la quantité de délai de groupe en utilisant des phaseurs réfléchissants passifs. Un phaseur passif et passe-tout (qui ne filtre aucune fréquence) affiche une perte qui est proportionnelle au retard de groupe, ce qui entraîne une distorsion du signal. Le chapitre trois présente une solution à ce problème, qui consiste en une mise en cascade d’un phaseur ayant du gain et un phaseur ayant des pertes.---------- ABSTRACT We are facing exploding demands for faster, more reliable, more energy-efficient radio systems, such as for instance 5G wireless communication. It is expected that for the next decade the mobile data capacity would exceed 1000 times higher than it is right now. Such high data volume requires large bandwidth spectrum resources. In low RF frequencies, the precious spectrum have been congested by zillions of radio devices. In high frequencies, such as millimeter wave, ultra wideband (UWB) spectrum is much easier available. However, processing UWB RF signal poses great difficulties on conventional digital signal processing (DSP) technique that has prevailed for low frequency and small bandwidth processing. For instance, DSP suffers limited speed, high cost and high power consumption for analog/digital conversion (ADC). Therefore, real-time and purely analog processing technique is desirable. In optics, people have been processing UWB RF signal with microwave photonics approaches, which is real-time, but involves expensive and lossy electrical/optical conversion. The direct radio Real-time Analog Signal Processing (R-ASP) is thus tractive but less exploited. Chapter 1 presents the advancements of R-ASP along with the contributions of the thesis. The core of R-ASP is “phaser”, which is a group delay engineered component that provides specified group delay function � (!). A phaser, in response to a wideband signal excitation, rearranges spectral components in time. The way a phaser arranges spectral components is controlled by the group delay function, � (!). Different R-ASP applications may require different group delay profiles. Chapter 2 introduces the concept of group delay engineering, different phaser technologies, and presents an R-ASP resolution (group delay swing) enhancement example using passive reflective phaser units. Passive phaser exhibits loss that is proportional to the group delay, i.e. imbalance amplitude, which typically results in undesired processing distortion. It is found that a phaser unit loaded with gain (G) and another loaded with equalized loss (L = 1/G) provide symmetric amplitudes (about 0 dB) and identical group delays. Cascading such gain and loss pair yields real all-pass amplitude. Moreover, the group delay can be tuned by the gain and loss. Chapter 3 introduces the gain-loss equalization concept, mathematically presents the device modeling, and experimentally demonstrated the prototype

Land vehicle antennas for satellite mobile communications

The RF performance, size, pointing system, and cost were investigated concepts are: for a mechanically steered 1 x 4 tilted microstrip array, a mechanically steered fixed-beam conformal array, and an electronically steered conformal phased array. Emphasis is on the RF performance of the tilted 1 x 4 antenna array and methods for pointing the various antennas studied to a geosynchronous satellite. An updated version of satellite isolations in a two-satellite system is presented. Cost estimates for the antennas in quantities of 10,000 and 100,000 unites are summarized

System-Level Integrated Circuit (SLIC) Technology Development for Phased Array Antenna Applications

This report documents the efforts and progress in developing a 'system-level' integrated circuit, or SLIC, for application in advanced phased array antenna systems. The SLIC combines radio-frequency (RF) microelectronics, digital and analog support circuitry, and photonic interfaces into a single micro-hybrid assembly. Together, these technologies provide not only the amplitude and phase control necessary for electronic beam steering in the phased array, but also add thermally-compensated automatic gain control, health and status feedback, bias regulation, and reduced interconnect complexity. All circuitry is integrated into a compact, multilayer structure configured for use as a two-by-four element phased array module, operating at 20 Gigahertz, using a Microwave High-Density Interconnect (MHDI) process. The resultant hardware is constructed without conventional wirebonds, maintains tight inter-element spacing, and leads toward low-cost mass production. The measured performances and development issues associated with both the two-by-four element module and the constituent elements are presented. Additionally, a section of the report describes alternative architectures and applications supported by the SLIC electronics. Test results show excellent yield and performance of RF circuitry and full automatic gain control for multiple, independent channels. Digital control function, while suffering from lower manufacturing yield, also proved successful

Improving the performance of wireless sensor networks using directional antennas

Over the last decades, lots of new applications have emerged thanks to the availability of small devices capable of wireless communications that form Wireless Sensor Networks (WSNs). These devices allow sensing, processing, and communication of multiple physical variables while keeping a low power consumption. During the last years, most of the research efforts were spent on the development and optimization of wireless communication protocols, aiming to maximize the reliability of the network while achieving the lowest possible power consumption. In this thesis, we study how to improve the performance of these WSNs by using directional antennas. Directional antennas can provide a higher gain and reduce the interference with other nodes by concentrating the radiated power in a certain direction. We present the different kinds of directional antennas available for WSNs, and we select the 6-element SPIDA antenna as a case of study. We present an electromagnetic model of this antenna, and we incorporate it into the COOJA network simulator. We report the first complete characterization of this antenna, including the radiation pattern and S11 parameters. The characterization shows that the antenna has a maximum gain of 6.8 dBi, a Half-Power Beamwidth (HPBW) of 113° and a module of S11 parameter of -7.5 dB at the central frequency (fc = 2.4525 GHz). We also present a novel way to optimize the antenna without changing its design by isolating multiple director elements. We show that with this technique, the performance of the antenna can be improved in terms of maximum gain, narrower HPBW, and a lower module of the S11 parameter without making any changes in the antenna itself. We evaluate the impact of supporting directional communications in the different layers of the network stack. We analyze the different challenges that arise and propose optimizations to overcome them in order to take advantage of the benefits of directional communication. We present an analysis of the state-of-the-art in neighbor discovery protocols for WSNs with directional antennas, and we propose, implement end evaluate two novel fully directional protocols: Q-SAND and DANDi. We compare both of them with SAND, a fully directional neighbor discovery protocol. DANDi is a fully directional asynchronous and dynamic neighbor discovery protocol where the contention resolution relies on a collision detection mechanism. To the best of our knowledge, DANDi is the fastest neighbor discovery protocol for WSN with directional antennas, with the additional advantage of being able to discover every reliable communication link in a network without requiring any prior information of the network topology. We combine the directional neighbor discovery protocol with MAC and routing optimizations in order fully take advantage of the benefits of using directional antennas. We focus on convergecast, a typical data collection application where every node sends packets periodically to a sink node. We present DirMAC, a novel MAC protocol that fully supports directional communication, together with four different heuristics to optimize the performance of the protocols. One of these heuristics has the added major benefit of being completely distributed and with no need for offline processing. Our evaluation shows that optimizations at both the MAC and routing layers are needed in order to reap the benefits of using directional antennas for convergecast. Our results show that the performance of the network can be greatly improved in terms of packet delivery rate, energy consumption, and energy per received packet, and that we obtain the largest performance improvements in networks with dense traffic. Simulations with different node densities show that when using directional antennas the PDR increases up to 29%, while energy consumption and energy per received packet decreases by up to 55% and 46% respectively. Experiments with real nodes validate these results showing a significant performance increase when using directional antennas in our scenarios, with a reduction in the RDC and EPRP of 25% and 15% respectively, while maintaining a PDR of 100%.Durante las últimas décadas, la disponibilidad de pequeños dispositivos con comunicación inalámbrica ha permitido el desarrollo de muchas nuevas aplicaciones. Estos dispositivos forman Redes de Sensores Inalámbricos (RSI, o WSN por sus siglas en inglés) que permiten sensar, procesar y comunicar datos provenientes de variables físicas, mientras que mantienen un bajo consumo energético. En los últimos años, la mayor parte de los esfuerzos de la comunidad científica estuvieron concentrados en el desarrollo y optimización de los protocolos de comunicación inalámbricos, buscando maximizar la confiabilidad de la red y minimizar el consumo energético. En esta tesis estudiamos cómo mejorar el rendimiento de las RSI usando antenas direccionales. Las antenas direccionales pueden proporcionar una mayor ganancia y reducir la interferencia con otros nodos al concentrar la potencia radiada en una cierta dirección. Comenzamos presentando los distintos tipos de antenas direccionales disponibles para las RSI, y seleccionamos la antena SPIDA de 6 elementos como caso de estudio. Luego presentamos un modelo electromagnético de la antena, que incorporamos al simulador de red COOJA. Construimos un primer prototipo con el que realizamos la primera caracterización completa de ésta antena, incluyendo el patrón de radiación y el parámetro S11. La caracterización muestra que la antena tiene una ganancia máxima de 6,8 dBi, un ancho de haz a mitad de potencia (HPBW por sus siglas en inglés) de 113° y un módulo del parámetro S11 de -7,5 dB en la frecuencia central (fc = 2,4525 GHz). También mostramos una forma innovadora de optimizar la antena sin cambiar su diseño utilizando varios elementos directores al mismo tiempo. Mostramos que con esta técnica se puede mejorar el rendimiento de la antena en términos de ganancia máxima, ancho de haz a mitad de potencia, y módulo del parámetro S11. Luego evaluamos el impacto de usar comunicaciones direccionales en las diferentes capas del stack de red. Analizamos los diferentes desafíos que surgen y proponemos optimizaciones para sortearlos. Presentamos un análisis del estado del arte en protocolos de descubrimiento de vecinos en RSI con antenas direccionales, y proponemos, implementamos y evaluamos dos protocolos direccionales : Q-SAND y DANDi. DANDi es un protocolo de descubrimiento de vecinos direccional, asíncrono y dinámico, donde la contienda por el canal se resuelve con un mecanismo basado en la detección de colisiones. Hasta donde sabemos, DANDi es el protocolo de descubrimiento de vecinos más rápido para RSI con antenas direccionales, con la ventaja adicional de que permite descubrir todos los enlaces de comunicación confiables de una red sin requerir ningún conocimiento previo de la topología. Luego combinamos los protocolos de descubrimiento de vecinos con optimizaciones en las capas de ruteo y acceso al medio para construir una aplicación de recolección de datos, donde cada nodo envía paquetes periódicamente a un nodo centralizador. Presentamos DirMAC, un protocolo de acceso al medio innovador que soporta comunicaciones direccionales, junto con cuatro heurísticas que permiten optimizar el rendimiento de los protocolos (una de ellas con la ventaja adicional que es totalmente distribuida). Los resultados muestran que usar antenas direccionales en este tipo de aplicaciones permite mejorar sustancialmente el rendimiento de la red, mostrando las mayores mejoras en redes con alto tráfico. Las simulaciones con diferentes densidades de nodos muestran que al usar antenas direccionales se puede aumentar el ratio de entrega de paquetes en hasta 29%, mientras que el consumo energético y la energía por paquete recibido bajan en hasta 55% y 46% respectivamente. Los experimentos en nodos reales validan estos resultados, mostrando una reducción en el consumo energético y en la energía por paquete recibido de 25% y 15% respectivamente, mientras que mantienen un ratio de entrega de paquetes de 100%

Miniaturized Microwave Devices and Antennas for Wearable, Implantable and Wireless Applications

This thesis presents a number of microwave devices and antennas that maintain high operational efficiency and are compact in size at the same time. One goal of this thesis is to address several miniaturization challenges of antennas and microwave components by using the theoretical principles of metamaterials, Metasurface coupling resonators and stacked radiators, in combination with the elementary antenna and transmission line theory. While innovating novel solutions, standards and specifications of next generation wireless and bio-medical applications were considered to ensure advancement in the respective scientific fields. Compact reconfigurable phase-shifter and a microwave cross-over based on negative-refractive-index transmission-line (NRI-TL) materialist unit cells is presented. A Metasurface based wearable sensor architecture is proposed, containing an electromagnetic band-gap (EBG) structure backed monopole antenna for off-body communication and a fork shaped antenna for efficient radiation towards the human body. A fully parametrized solution for an implantable antenna is proposed using metallic coated stacked substrate layers. Challenges and possible solutions for off-body, on-body, through-body and across-body communication have been investigated with an aid of computationally extensive simulations and experimental verification. Next, miniaturization and implementation of a UWB antenna along with an analytical model to predict the resonance is presented. Lastly, several miniaturized rectifiers designed specifically for efficient wireless power transfer are proposed, experimentally verified, and discussed. The study answered several research questions of applied electromagnetic in the field of bio-medicine and wireless communication.Comment: A thesis submitted for the degree of Ph

Real-Time Microwave Signal Processing: Dispersion Engineering and Time Modulation

RÉSUMÉ Il y a aujourd’hui une demande pour des systèmes radiofréquences ayant une large bande passante, une faible latence, des bas coûts, une grande fiabilité et une faible consommation d’énergie. Par exemple, la prochaine génération de systèmes sans fil mobiles devrait avoir une capacité mille fois plus élevée qu’aujourd’hui pour répondre aux exigences de diverses applications telles que les véhicules sans pilote et la télémédecine. Bien que la technolo-gie dominante actuelle, le traitement de signal numérique (DSP en anglais), soit compacte, flexible et précise, elle sou˙re de problèmes fondamentaux, notamment une consommation d’énergie élevée, une conversion analogique-numérique coûteuse, une bande passante limitée, un stockage en mémoire faible et une mauvaise performance aux hautes fréquences. Par con-séquent, nous proposons ici d’e˙ectuer le traitement du signal micro-ondes analogiquement et en temps réel. Cette technique attrayante a été peu explorée jusqu’à présent, et pourrait remplacer ou complémenter le traitement numérique. Le chapitre 1 présente la motivation du traitement du signal micro-ondes analogique en temps réel (R-MSP), deux solutions R-MSP complémentaires basées respectivement sur l’ingénierie de la dispersion et la modulation du temps, ainsi que les contributions de cette thèse. Les chapitres 2 et 3 proposent deux applications basées sur l’ingénierie de dispersion pour le traitement des signaux micro-ondes. Cette technologie est inspirée de l’optique ultra-rapide, où les signaux électromagnétiques sont traités en temps réel à l’aide de composants optiques dispersifs. Dans le domaine des micro-ondes, ces composants conçus pour la dispersion ont reçu le nom de "phaseurs" et, comme leurs homologues optiques, manipulent la phase ou le retard de groupe des signaux d’entrée. En concevant les caractères de dispersion des composants, diverses fonctions peuvent être réalisées. Le chapitre 2 présente un transformateur de Hilbert hyperfréquence. Ce transformateur de Hilbert est basé sur la combinaison d’un coupleur et d’un résonateur en boucle. La fonction de transfert du transformateur est dérivée à l’aide de graphiques de flux de signaux, et deux chi˙res de mérite sont introduits pour caractériser eÿcacement le dispositif. De plus, une explication détaillée de son fonctionnement physique est fournie. Le transformateur micro-ondes de Hilbert est démontré expérimentalement dans trois applications: pour la détection d’un front d’onde, pour la suppression de la crête et pour la modulation à bande latérale unique.----------ABSTRACT Today’s exploding demands for wider bandwidth, lower latency, lower cost and more reliable and power-efficient radio systems bring more challenges for signal processing technologies. For example, the next generation mobile wireless systems in the coming decade is expected to have thousand times higher capacity than it is right now to meet the requirements of various applications, for instance, unmanned vehicles and telemedicines. Although current dominant technology, digital signal processing (DSP), offers the benefits of device compactness and processing flexibility and preciseness, it also suffers fundamental issues, including high power consumption, high-cost analog-digital conversion, limited operating bandwidth, low memory storage, and poor performance at high frequencies. Therefore, processing microwave signal in real time and purely analog domain as an alternative or complementary technique is desired, which is attractive but less explored till now. Chapter 1 introduces the motivation of real-time microwave signal processing (R-MSP) and two complementary R-MSP solutions based on dispersion engineering and time modulation, respectively, along with the contributions of this thesis. Dispersion engineering based microwave signal processing is a signal processing technology inspired from ultra-fast optics, where electromagnetic signals are processed in real-time using dispersive optical components. In microwave domain, these dispersion-engineered components have been given the name "phasers" and, similar to its optical counterpart, manipulates the phase or the group delay of input signals. By engineering the dispersion characters of the components, various functions may be realized. In chapters 2 and 3, two applications based on dispersion engineering for microwave signal processing are proposed. Chapter 2 presents a microwave Hilbert transformer as a new component for R-MSP. This Hilbert transformer is based on the combination of a branch-line coupler and a loop resonator. The transfer function of the transformer is derived using signal flow graphs, and two figures of merits are introduced to effectively characterize the device. Moreover, a detailed physical explanation of its physical operation is provided. The microwave Hilbert transformer is demonstrated experimentally in three applications: edge detection, peak suppression and single sideband modulation. Chapter 3 presents a design of dispersion engineering based a planar Rotman lens spectrum decomposer (RL-SD) with the features resolution flexibility, input port position arbitrariness and frequency range and resolution tunability. The resolution flexibility consists in allowing diffrent frequency sampling functions by properly distributing the output port locations

Formulation and Synthesis of Hexagonal Prism Array Using Nature Inspired Algorithm

In this dissertation a new architecture of antenna array is proposed in which antenna elements are placed on a Hexagonal Prism in order to obtain split beam radiation pattern.The Hexagonal Prism Array(HPA) is synthesized for amplitude excitation ,complex excitation and relative distance using a novel optimisation technique.As a performance criteria the split beam radiation pattern is evaluated for side lobe level(SLL) and half power beam width(HPBW).The optimisation technique is experimented on conventional arrays like Linear and Planar and a comparative study with the published literature is also performed.An attempt to model the HPA on a commercial software in which radiator is a patch elements