Near field imaging using microwaves in medical applications is of great current interest for its capability and accuracy in identifying features of interest, in comparison with other known screening tools. Many imaging methods have been developed over the past two decades showing the potential of microwave imaging in medical applications such as early breast cancer detection, analysis of cardiac tissues, soft tissues and bones. Microwave imaging uses non-ionizing ultra wideband (UWB) electromagnetic signals and utilises tissue-dependent dielectric contrast to reconstruct signals and images using radar-based or tomographic imaging techniques. Microwave imaging offers low health risk, low operational cost, ease of use and user-friendliness. This study documents microwave imaging experiments for early breast cancer detection and bone fracture detection using radar approach. An actively tuned UWB patch antenna and a UWB Vivaldi antenna are designed and utilised as sensing elements in the aforementioned applications. Both UWB antennas were developed over a range of frequency spectrum, and then characteristics were tested against their ability for microwave imaging applications by reconstructing the 3D Inversion Algorithm. An experiment was conducted using patch antenna to test the detection of variable sizes of cancer tissues based on a simple phantom consisting of a plastic container with a low dielectric material emulating fatty tissue and high dielectric constant object emulating a tumour, is scanned between 4 to 8 GHz with the patch antenna. A 2-D image of the tumour is constructed using the reflected signal response to visualize the location and size of the tumour. A Vivaldi antenna is designed covering 3.1 to 10.6 GHz. The antenna is tested via simulation for detecting bone fractures of various sizes and 2-D images are generated using reflected pulses to show the size of fracture. The Vivaldi antenna is optimised for early breast cancer detection and detailed simulated study is carried out using different breast phantoms and tumour sizes. Simulations are backed with the experimental investigation with the test setup used for patch antenna. Generated images for simulations and experimental investigation show good agreement, and show the presence of tumour with good location accuracy. Measurements indicate that both prototype microwave sensors are good candidates for tested imaging applications.

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Yes / A novel dual-polarized patch antenna for ultra-wideband (UWB) applications is presented. The antenna consists of a square patch and four capacitively coupled feeds to enhance the impedance bandwidth. Each feed is formed by a vertical isosceles trapezoidal patch and a horizontal isosceles triangular patch. The four feeds are connected to the microstrip lines that are printed on the bottom layer of the grounded FR4 substrate. Two tapered baluns are utilized to excite the antenna to achieve high isolation between the ports and reduce the cross-polarization levels. In order to increase the antenna gain and reduce the backward radiation, a compact surface mounted cavity is integrated with the antenna. The antenna prototype has achieved an impedance bandwidth of 112% at (|S11| ≤ -10 dB) whereas the coupling between the two ports is below -28 dB across the operating frequency range. The measured antenna gain varies from 3.91 to 10.2 dBi for port 1 and from 3.38 to 9.21 dBi for port 2, with a 3-dB gain bandwidth of 107%. / IEEE Antennas and Propagation Society

No / To mitigate potential interferences with coexisting wireless systems operating over 3.3-3.6 GHz, 5.15-5.35 GHz, or 5.725-5.825 GHz bands, four novel band-notched antennas suitable for ultra-wideband (UWB) applications are proposed. These include UWB antennas with a single wide notched band, a single narrow notched band, dual notched bands, and triple notched bands. Each antenna comprises a half-circle shaped patch with an open rectangular slot and a half-circle shaped ground plane. Good band-notched performance is achieved by using high permittivity and low dielectric loss substrate, and inserting quarter-wavelength horizontal/vertical stubs or alternatively embedding quarter-wavelength open-ended slots within the feed line. The results of both simulation and measurement confirm that the gain suppression of the single and multiple band-notched antennas in each desired notched band are over 15 dB and 10 dB, respectively. The radiation pattern of the proposed triple band-notched design is relatively stable across the operating frequency band.

Dielectric resonator antenna (DRA) technologies are applicable to a wide variety of mobile wireless communication systems. The principal energy loss mechanism for this type of antenna is the dielectric loss, and then using modern ceramic materials, this may be very low. These antennas are typically of small size, with a high radiation efficiency, often above 95%; they deliver wide bandwidths, and possess a high power handling capability. The principal objectives of this thesis are to investigate and design DRA for low profile personal and nomadic communications applications for a wide variety of spectrum requirements: including DCS, PCS, UMTS, WLAN, UWB applications. X-band and part of Ku band applications are also considered. General and specific techniques for bandwidth expansion, diversity performance and balanced operation have been investigated through detailed simulation models, and physical prototyping. The first major design to be realized is a new broadband DRA operating from 1.15GHz to 6GHz, which has the potential to cover most of the existing mobile service bands. This antenna design employs a printed crescent shaped monopole, and a defected cylindrical DRA. The broad impedance bandwidth of this antenna is achieved by loading the crescent shaped radiator of the monopole with a ceramic material with a permittivity of 81. The antenna volume is 57.0  37.5  5.8 mm3, which in conjunction with the general performance parameters makes this antenna a potential candidate for mobile handset applications. The next class of antenna to be discussed is a novel offset slot-fed broadband DRA assembly. The optimised structure consists of two asymmetrically located cylindrical DRA, with a rectangular slot feed mechanism. Initially, designed for the frequency range from 9GHz to 12GHz, it was found that further spectral improvements were possible, leading to coverage from 8.5GHz to 17GHz. Finally, a new low cost dual-segmented S-slot coupled dielectric resonator antenna design is proposed for wideband applications in the X-band region, covering 7.66GHz to 11.2GHz bandwidth. The effective antenna volume is 30.0 x 25.0 x 0.8 mm3. The DR segments may be located on the same side, or on opposite sides, of the substrate. The end of these configurations results in an improved diversity performance. / General Secretariat of Education and Scientific Research Libya

[ES] La cápsula inalámbrica de endoscopia (WCE) es una tecnología notable y atractiva adoptada en el sector biomédico hace varios años. WCE proporciona una tecnología de imagen inalámbrica no invasiva que permite a los especialistas reconocer y diagnosticar enfermedades que afectan todo el tracto gastrointestinal. Aunque los médicos pueden recibir imágenes claras de anomalías en el tracto gastrointestinal, no tienen información sobre sus exacta ubicación. La localización precisa de los trastornos detectados es crucial para el posterior procedimiento de extracción mediante cirugía. Actualmente, la banda de frecuencia asignada para aplicaciones de cápsula endoscópica es la banda MICS (402-405 MHz) que ofrece una velocidad de datos de hasta 500 kbps, insuciente para transmitir imágenes de alta calidad. Recientemente, la tecnología de banda ultra ancha (UWB) ha estado atrayendo atención como posible candidato para la próxima generación de cápsula endoscópica. Las ventajas de UWB incluyen arquitecturas de transceptor simples que permiten bajo consumo de potencia, baja interferencia a otros sistemas y amplio ancho de banda que resulta en comunicaciones a una velocidad de datos más alta. En esta disertación, el rendimiento de las técnicas de localización de WCE basadas en radiofrecuencia (RF) se investiga a través de simulaciones software, medidas experimentales de laboratorio que involucran fantomas homogéneos y heterogéneos y a través de experimentos in vivo que constituyen el escenario de prueba más realista. La tecnología UWB (3.1-10.6 GHz) se considera como interfaz de comunicación para aplicaciones de cápsula endoscópica. En tal escenario, el transmisor inalámbrico está ubicado en el tracto gastrointestinal, mientras que uno o más receptores inalámbricos están ubicados sobre la supercie del cuerpo. El enfoque basado en la potencia recibida (RSS) se investiga principalmente debido a su simplicidad de implementación y menos sensibilidad a las limitaciones de ancho de banda. Se analiza el impacto de la posición y del número de receptores seleccionados en la precisión de la localización. Finalmente, se desarrolla una interfaz gráfica de usuario (GUI) para visualizar los resultados de la localización en tres dimensiones (3D) obtenidos mediante las medidas in vivo. / [CA] La càpsula sense fil d'endoscòpia (WCE) és una tecnologia notable i atractiva adoptada en el sector biomèdic fa diversos anys. La WCE proporciona una tecnologia d'imatge sense fil no invasiva que permet als especialistes reconéixer i diagnosticar malalties que afecten tot el tracte gastrointestinal. Encara que els metges poden rebre imatges clares d'anomalies en el tracte gastrointestinal, no tenen informació sobre les seues exacta ubicació. La localització precisa dels trastorns detectats és crucial per al posterior procediment d'extracció mitjançant cirurgia. Actualment, la banda de freqüència assignada per a aplicacions de càpsula endoscòpica és la banda MICS (402-405 MHz) que ofereix una velocitat de dades de fins a 500 kbps, insucient per a transmetre imatges d'alta qualitat. Recentment, la tecnologia de banda ultra ampla (UWB) ha estat atraient atenció com a possible candidata per a la pròxima generació de càpsula endoscòpica. Els avantatges d' UWB inclouen arquitectures de transceptor simples que permeten un baix consum de potència, baixa interferència amb altres sistemes i una gran amplada de banda que resulta en comunicacions a una velocitat de dades més alta. En aquesta dissertació, el rendiment de les tècniques de localització de WCE basades en radiofrequència (RF) s'investiga a través de simulacions amb programari, mesures experimentals de laboratori que involucren fantomes homogenis i heterogenis i a través d'experiments in vivo que constitueixen l'escenari de prova més realista. La tecnologia UWB (3.1-10.6 GHz) es considera com a interfície de comunicació per a aplicacions de càpsula endoscòpica. En tal escenari, el transmissor sense fil està situat en el tracte gastrointestinal, mentre que un o més receptors sense fils estan situats sobre la superfície del cos. L'enfocament basat en la potència rebuda (RSS) s'investiga principalment a causa de la seua simplicitat d'implementació i menys sensibilitat a les limitacions d'amplada de banda. S'analitza l'impacte de la posició i del numere de receptors seleccionats en la precisió de la localització. Finalment, es desenvolupa una interfície gràca d'usuari (GUI) per a visualitzar els resultats de la localització en tres dimensions (3D) obtinguts mitjançant les mesures in vivo. / [EN] Wireless Capsule Endoscopy (WCE) is a remarkable and attractive technology adopted in the biomedical sector several years ago. It provides a non-invasive wireless imaging technology for the entire gastrointestinal (GI) tract. WCE allows specialists to recognize and diagnose diseases affecting the whole GI tract. Although physicians can receive clear pictures of abnormalities in the GI tract, they have no information about their exact location. Precise localization of the detected disorders is crucial for the subsequent removal procedure by surgery. Currently, the frequency band allocated for capsule endoscopy applications is the MICS band (402-405 MHz). This band offers data rate up to 500 kbps, which is insufficient to transmit high quality images. Recently, Ultrawideband (UWB) technology has been attracting attention as potential candidate for next-generation WCE systems. The advantages of UWB include simple transceiver architectures enabling low power consumption, low interference to other systems and wide bandwidth resulting in communications at higher data rate. In this dissertation, performance of WCE localization techniques based on Radio Frequency (RF) information are investigated through software simulations, experimental laboratory measurements involving homogeneous and heterogeneous phantom models and in vivo experiments which constitute the most realistic testing scenario. Ultra-Wideband technology (3.1-10.6 GHz) is considered as communication interface in Wireless Capsule Endoscopy. In such scenario, the wireless transmitter is located in the gastrointestinal track while one or more wireless receivers are located over the surface of the body. Received Signal Strength (RSS)-based approach is mainly explored due to its implementation simplicity and less sensitivity to bandwidth limitations. Impact of the position and the number of selected receivers on the localization accuracy is analyzed. Finally, a graphical user interface (GUI) is developed to visualize the three-dimensional (3D) localization results obtained through in vivo measurements. / Barbi, M. (2019). Location and Tracking for Ultra-WideBand In-Body Communications in Medical Applications [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/132874

The recent progress in electronics and communication technologies has driven the unprecedented demand for multi-functional wireless communication in most single wireless devices. However, employing the limited spectrum effectively on communication equipment poses a key design challenge, as most antennas often suffer from bandwidth limitations and restricted frequency rarge. Onekey approach to overcome this problem without significantly affecting the antenna size is to apply antenna tuneability and reconfigurability. This is achieved by electronically changing some properties of the antenna usually by loading the reactive loading of the resonator by means of active electronic elements including varactor diode or PIN diode with extra circuitry. The main objective of this research is to design and investigate low-profile antennas for heterogeneous wireless systems using the antenna reconfigurability concept through tuning and/or using the MIMO antenna techniques. The research focuses on antenna design and implementation to cover various wireless standards and applications within the electromagnetic spectrum including UMTS (1.92-2.17 GHz), Cognitive Radio such as WLAN and WiMAX (2.4GHz), Wi-Fi (5.2GHz), 5G (600MHz - 6GHz) and MBAN applications. A family of compact microstrip printed reconfigurable antennas for various cognitive radio applications is presented. Effects of various slots on the antenna performance are also investigated, and the final version was reconfigured across a broad frequency range (1.5 - 2.4 GHz) Furthermore, four new variants of the miniaturised hexagonal-shaped monopole printed antennas for different UWB applications are proposed. Prototypes of the four versions are fabricated and compared to establish their results. Two reconfigurable rejection bands are introduced to avoid anticipated interference with other systems working within the UWB range. Finally, a novel low-profile four-element MIMO antenna was designed and fabricated to operate at the 2.4 GHz ISM band. both measurements and simulation results revealed strong agreement. Furthermore, the designed antenna was also tested on human tissues, with acceptable results when compared to its performance in free space. it is proved to be a good fit for wireless, mobile communications, medical systems and WBAN applications. / Libyan Ministry of Higher Education. / Subtitle: Simulation and Measurement of Reconfigurable Antennas for Cognitive Radio, UWB Applications, Investigation of Antenna Gain and Efficiency, Frequency Tuneable Range, Antenna Radiation Performance and Antenna Design Optimization using Parametric Studies as well as using MIMO antenna for wireless body area networks

Les circuits de récupération d'horloge et de données sont nécessaires au bon fonctionnement de plusieurs systèmes de communication sans fil. Les travaux effectués dans le cadre de cette thèse concernent le développement de ces circuits avec d'une part la réalisation, en technologie HCMOS9 0,13 μm de STMICROELECTRONICS, de circuits CDR analogiques à 1 et 54 Mbit/s, et d'autre part, la mise en œuvre de fonctions CDR numériques programmables à bas débit. Un circuit CDR fonctionnant à plus bas débit (1 Mbit/s) a été conçu dans le cadre de la gestion d'énergie d'un récepteur ULB impulsionnel non cohérent. Ces deux structures ont été réalisées à l'aide de PLL analogiques du 3ème ordre. Un comparateur de phase adapté aux impulsions issues du détecteur d'énergie a été proposé dans cette étude. Les circuits ont ensuite été dimensionnés dans le but d'obtenir de très bonnes performances en termes de jitter et de consommation. En particulier, les performances mesurées (sous pointes) du circuit CDR à 1 Mbit/s permettent d'envisager une gestion d'énergie efficace (réduction de plus de 97% de la consommation du récepteur). Dans le cadre d'une chaîne de télémesure avion vers sol, deux circuits CDR numériques ont également été réalisés durant cette thèse. Une PLL numérique du second degré a été implémentée en vue de fournir des données et une horloge synchrone de celles-ci afin de piloter une chaîne SOQPSK entièrement numérique. Un circuit ELGS a également mis au point pour fonctionner au sein d'un récepteur PCM/FM. / Clock and data recovery circuits are required in many wireless communication systems. This thesis is about development of such circuits with: firstly, the realization, in HCMOS9 0.13 μm of STMICROELECTRONICS technology, of 1 and 54 Mb/s analog CDR circuits, and secondly, the implementation of programmable digital circuits at low rates. In the aim of an impulse UWB transceiver dealing with video transmission, a CDR circuit at 54 Mb/s rate has been realized to provide clock signal synchronously with narrow pulses (their duration is about a few nanoseconds) from the energy detector. Another CDR circuit has been built at 1 Mb/s rate in a non-coherent IR- UWB receiver power management context. Both circuits have been implemented as 3rd order analog PLL. In this work, a phase comparator suitable for “RZ low duty cycle” data from the energy detector has been proposed. Circuits have been sized to obtain very good performances in terms of jitter and power consumption. Particularly, measured performances of the 1 Mb/s CDR circuit allow to plan an efficient power management (a decrease of more than 97% of the receiver total power consumption). In the context of a telemetry system from aircraft to ground, two digital CDR circuits have also been implemented. A second order digital PLL has been adopted in order to provide synchronous clock and data to an SOQPSK digital transmitter. Also, a digital ELGS circuit has been proposed to work in a PCM/FM receiver. For both CDR structures, the input signal rate is programmable and varies globally from 1 to 30 Mb/s.

La radio impulsionnelle UWB (IR-UWB) est une technologie de communication relativement récente, qui apporte une solution intéressante au problème de l’encombrement du spectre RF, et qui répond aux exigences de haut débit et localisation précise d’un nombre croissant d’applications, telles que les communications indoor, les réseaux de capteurs personnels et corporels, l’IoT, etc. Ses caractéristiques uniques sont obtenues par la transmission d’impulsions de très courte durée (inférieure à 1 ns), occupant une largeur de bande allant jusqu’à 7,5 GHz, et ayant une densité spectrale de puissance extrêmement faible (inférieure à -43 dBm/MHz). Les meilleures performances d’un système IR-UWB sont obtenues avec des récepteurs cohérents de type Rake, au prix d’une complexité accrue, due notamment à l’étape d’estimation du canal UWB, caractérisé par de nombreux trajets multiples. Cette étape de traitement nécessite l’estimation d’un ensemble de composantes spectrales du signal reçu, sans pouvoir faire appel aux techniques d’échantillonnage usuelles, en raison d’une limite de Nyquist particulièrement élevée (plusieurs GHz).Dans le cadre de cette thèse, nous proposons de nouvelles approches, à faible complexité, pour l’estimation du canal UWB, basées sur la représentation parcimonieuse du signal reçu, la théorie de l’acquisition compressée, et les méthodes de reconstruction des signaux à taux d’innovation fini. La réduction de complexité ainsi obtenue permet de diminuer de manière significative le coût d’implémentation du récepteur IR-UWB et sa consommation. D’abord, deux schémas d’échantillonnage compressé, monovoie (filtre SoS) et multivoie (MCMW) identifiés dans la littérature sont étendus au cas des signaux UWB ayant un spectre de type passe-bande, en tenant compte de leur implémentation réelle dans le circuit. Ces schémas permettent l’acquisition des coefficients spectraux du signal reçu et l’échantillonnage à des fréquences très réduites ne dépendant pas de la bande passante des signaux, mais seulement du nombre des trajets multiples du canal UWB. L’efficacité des approches proposées est démontrée au travers de deux applications : l’estimation du canal UWB pour un récepteur Rake cohérent à faible complexité, et la localisation précise en environnement intérieur dans un contexte d’aide à la dépendance.En outre, afin de réduire la complexité de l’approche multivoie en termes de nombre de voies nécessaires pour l’estimation du canal UWB, nous proposons une architecture à nombre de voies réduit, en augmentant le nombre d’impulsions pilotes émises.Cette même approche permet aussi la réduction de la fréquence d’échantillonnage associée au schéma MCMW. Un autre objectif important de la thèse est constitué par l’optimisation des performances des approches proposées. Ainsi, bien que l’acquisition des coefficients spectraux consécutifs permette une mise en oeuvre simple des schémas multivoie, nous montrons que les coefficients ainsi choisis, ne donnent pas les performances optimales des algorithmes de reconstruction. Ainsi, nous proposons une méthode basée sur la cohérence des matrices de mesure qui permet de trouver l’ensemble optimal des coefficients spectraux, ainsi qu’un ensemble sous-optimal contraint où les positions des coefficients spectraux sont structurées de façon à faciliter la conception du schéma MCMW. Enfin, les approches proposées dans le cadre de cette thèse sont validées expérimentalement à l’aide d’une plateforme expérimentale UWB du laboratoire Lab-STICC CNRS UMR 6285. / Ultra-wideband impulse radio (IR-UWB) is a relatively new communication technology that provides an interesting solution to the problem of RF spectrum scarcity and meets the high data rate and precise localization requirements of an increasing number of applications, such as indoor communications, personal and body sensor networks, IoT, etc. Its unique characteristics are obtained by transmitting pulses of very short duration (less than 1 ns), occupying a bandwidth up to 7.5 GHz, and having an extremely low power spectral density (less than -43 dBm / MHz). The best performances of an IR-UWB system are obtained with Rake coherent receivers, at the expense of increased complexity, mainly due to the estimation of UWB channel, which is characterized by a large number of multipath components. This processing step requires the estimation of a set of spectral components for the received signal, without being able to adopt usual sampling techniques, because of the extremely high Nyquist limit (several GHz).In this thesis, we propose new low-complexity approaches for the UWB channel estimation, relying on the sparse representation of the received signal, the compressed sampling theory, and the reconstruction of the signals with finite rate of innovation. The complexity reduction thus obtained makes it possible to significantly reduce the IR-UWB receiver cost and consumption. First, two existent compressed sampling schemes, single-channel (SoS) and multi-channel (MCMW), are extended to the case of UWB signals having a bandpass spectrum, by taking into account realistic implementation constraints. These schemes allow the acquisition of the spectral coefficients of the received signal at very low sampling frequencies, which are not related anymore to the signal bandwidth, but only to the number of UWB channel multipath components. The efficiency of the proposed approaches is demonstrated through two applications: UWB channel estimation for low complexity coherent Rake receivers, and precise indoor localization for personal assistance and home care.Furthermore, in order to reduce the complexity of the MCMW approach in terms of the number of channels required for UWB channel estimation, we propose a reduced number of channel architecture by increasing the number of transmitted pilot pulses. The same approach is proven to be also useful for reducing the sampling frequency associated to the MCMW scheme.Another important objective of this thesis is the performance optimization for the proposed approaches. Although the acquisition of consecutive spectral coefficients allows a simple implementation of the MCMW scheme, we demonstrate that it not results in the best performance of the reconstruction algorithms. We then propose to rely on the coherence of the measurement matrix to find the optimal set of spectral coefficients maximizing the signal reconstruction performance, as well as a constrained suboptimal set, where the positions of the spectral coefficients are structured so as to facilitate the design of the MCMW scheme. Finally, the approaches proposed in this thesis are experimentally validated using the UWB equipment of Lab-STICC CNRS UMR 6285.