Two experiments were conducted to investigate Adaptive Noise Cancelling and Cepstrum echo removal post-processing techniques on acoustic data from a linear microphone array in an anechoic chamber. A point source speaker driven with white noise was used as the primary signal. The first experiment included a background speaker to provide interference noise at three different Signal-to-Noise Ratios to simulate noise propagating down a wind tunnel circuit. The second experiment contained only the primary source and the wedges were removed from the floor to simulate reflections found in a wind tunnel environment. The techniques were applicable to both signal microphone and array analysis. The Adaptive Noise Cancellation proved successful in its task of removing the background noise from the microphone signals at SNRs as low as -20 dB. The recovered signals were then used for array processing. A simulation reflection case was analyzed with the Cepstral technique. Accurate removal of the reflection effects was achieved in recovering both magnitude and phase of the direct signal. Experimental data resulted in Cepstral features that caused errors in phase accuracy. A simple phase correction procedure was proposed for this data, but in general it appears that the Cepstral technique is and would be not well suited for all experimental data. / Master of Science

As multimedia devices advance, current high-speed wireless standards may soon struggleto support their growing demand for data speeds. This results in limitations in bandwidthfor applications, notably affecting activities like streaming high-definition television andultra-high-definition video. The proposed solution is to go up in frequency (millimeterwaves) allowing for use of greater bandwidths, in new bands. A problem is, however,that the path loss at mmWave frequencies is substantially greater than at frequencies below6GHz, currently the main frequency range used by both cellular and Wi-Fi. In order tocompensate for the increase in pathloss, wireless systems operating at mmWave frequenciesneed to use high gain antennas e.g. antenna arrays. Such arrays operate using digital oranalog beamforming. In this thesis the design, fabrication and verification of an analogbeamforming network connected to a four-antenna element patch array implemented at26GHz on a four-layer printed circuit board is presented. The components of the structuresof the Butler matrix beamforming network were designed and evaluated in simulationsusing CST. The stack up is a four-layer PCB-board with antenna elements and feedingnetwork on opposite outer layers. All structures in the Butler matrix were constructedin micro strip line with characteristic impedance of 50 ohm on Rogers RT-duroid 5880substrate to reduce dielectric losses. The designed 4x4 Butler matrix aimed at four set stateswith progressive phase differences ±45 and ±135 resulting in main lobes with direction -40,-15, 14 and 39 degrees. In the simulation, a progressive phase difference up to a deviationof up to 8.6 degrees was observed for all states. The fabricated Butler matrix was verified onan antenna measurement range to have main lobe directions of -45, -15, 15 and 40 degreesand with half power beam widths (HPBW) of 27.5, 25, 25 and 27.5 degrees respectively.The nulls between each lobe in the radiation pattern had a relative gain compared to peakvalue of -12.2 dBi resulting in similar magnitude as noise floor. The side lobe suppressionwere evaluated to minimum of 6.3 dB. The high directivity and well-defined nulls confirmthe hybrid couplers properties of equal power division as well as phase difference betweenoutput ports. The patch antennas were verified to have a dominant linear polarization butthe peak value for all lobes shows a deviation of -4.1 dB for all measurements comparedto simulation. In conclusion the final patch antenna array and Butler matrix performed asexpected from the simulation. Indicating that the proposed analog beam forming antennadesign is robust and well suited to be used in e.g. Open RAN applications.

Deployment of antenna arrays is a very promising solution to reduce the Multiple Access Interference (MAI) from high data rate users in the Wideband Code Division Multiple Access (W-CDMA) system. Combining the antenna array with a RAKE receiver, both of which exploits multipath diversity, can significantly improve the system performance. In this research, we investigate the performance of these beamformer-RAKE receivers, also known as two-dimensional (2-D) RAKE receiver, for the reverse link of the W-CDMA system. We consider three different Pilot Symbol Assisted (PSA) beamforming techniques, Direct Matrix Inversion (DMI), Least-Mean Square (LMS) and Recursive Least Square (RLS) adaptive algorithms. Two different Geometrically Based Single Bounce (GBSB) statistical channel models are considered, one, which is more suitable for array processing, and the other is conductive to RAKE combining. The performances of the 2-D RAKE receivers are evaluated in these two channel models as a function of the number of antenna elements and RAKE fingers. It is shown that, in both the cases, the 2-D RAKE receiver outperforms the conventional RAKE receiver and the conventional beamformer by a significant margin. Also, the output SINR expression of a 2-D RAKE receiver with the general optimum beamformer is derived. / Master of Science

Esta tesis doctoral aborda el estudio y análisis de la acústica de salas mediante un proceso de descomposición del campo sonoro muestreado con arrays circulares de micrófonos. El comportamiento acústico de una sala teniendo en cuenta todos los factores espaciales no es algo trivial. Este problema es conocido desde la antigüedad: griegos y romanos comenzaron a cuidar las cualidades acústicas en sus construcciones arquitectónicas basándose principalmente en diseños puramente prácticos. Más tarde sería el físico Sabine y su modelo estadístico para la medida del tiempo de reverberación de salas en que daría lugar al análisis moderno de la acústica arquitectónica. En la actualidad existen múltiples y avanzados métodos de análisis basados en el estudio de las respuestas al impulso de las salas capturadas mediante la utilización de fuentes de sonido y micrófonos de precisión que han contribuido a nuevos avances y mejoras dentro de este campo de la acústica. Los métodos mas modernos propuestos recientemente utlizan arrays de micrófonos para intentar capturar el campo de forma más precisa y con todas sus características espaciales, sin embargo todavía no han sido explotados convenientemente para obtener conclusiones significativas y relevantes sobre la acústica final de salas y sus aspectos geométricos. En esta tesis se lleva a cabo una metodología de análisis de salas basada en técnicas de descomposición de onda plana y de beamforming modal. Mediante la construcción de un array circular con micrófonos cardioides, así como de la implementación de un algoritmo de deteccion de máximos locales en ecogramas basado en morfología de imagen, se obtienen, analizan y comparan la acústica de las salas (reflexiones, absorciones, etc) permitiendo extrapolar una serie de conclusiones sobre sus características, comportamiento y calidad. Los resultados obtenidos por ambos métodos de análisis se comparan para identificar las reflexiones más significativas de las salas extrayendo informaci / Torres Aranda, AM. (2012). ANÁLISIS DE LA ACÚSTICA DE SALAS MEDIANTE LA UTILIZACIÓN DE ARRAYS DE MICRÓFONOS CIRCULARES [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/18221

In this work we propose the apodization or windowing of the coupling coefficients of the unit cells conforming a coupled resonator device as a mean to reduce the level of secondary sidelobes in the case of SCISSOR configuration [7] or reducing the passband ripples in the case of CROW configuration [8]. This technique is regularly employed in the design of digital filters [18] and has been applied as well in the design of other photonic devices such as corrugated waveguide filters [9] and fiber Bragg gratings [19]. We also propose a novel technique for the apodization of coupled resonator structures by applying a longitudinal offset between resonators in order to modify the power coupling constant, which alleviates the technical requirements required for the production of these devices. We will demonstrate the design, fabrication and characterization of CROW structures employing the apodization through the aforementioned technique. / Doménech Gómez, JD. (2013). Apodized Coupled Resonator Optical Waveguides: Theory, design and characterization [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/32278

[ES] La tecnologia en fases de paquets es va convertir en dècades enrere en la indústria del radar. Avui en dia, la matriu de fases o la formació de bigues s'està convertint en una necessitat per a la comunicació digital. L'explotació d'un sistema de transmissió de feixos ajudarà a reduir el consum total d'energia de les estacions base i dels equips d'usuaris. També permetrà al servei oferir dades molt més elevades i millorar la qualitat del servei. La investigació sobre la comunicació digital i la comunicació requereix una antena i un maquinari compatible. El maquinari hauria de ser capaç de gestionar diferents escenaris i enfocaments per a problemes de comunicació mòbil. Hi ha diversos sistemes utilitzats per a la investigació de la formació de bigues, especialment per a la comunicació mòbil. Aquests sistemes pateixen de diverses deficiències. Són cares d'implementar, no adaptatives i fixades a una arquitectura relacionada amb determinat algorisme de generació de feixos o amb un nombre d'elements d'array fix. En aquesta tesi es proposa un nou sistema de matrius per fases. Aquest sistema es podria explotar per a la investigació en problemes de comunicació mòbil o radar. Està compost per una xarxa d'antenes planes de 8x1, canals de conversió de RF a banda base i processador de banda base. Es fa una estimació de la transformació de fases i de la DOA en mostres digitals de banda base. Això proporciona al sistema dinàmica quant als algorismes provats. Amb aquesta finalitat, es fan servir juntes SDR àgils per adquirir senyals de la matriu d'antenes i convertir-les en fluxos de dades digitals. Els fluxos de dades es processen després en un processador de banda base basat en FPGA. A més de ser baixos en costos i assequibles per part de petits instituts d'investigació i investigacions independents, el sistema es pot ajustar per portar més elements de matriu d'antenes. La matriu monopola plana de 8x1 està dissenyada, simulada i mesurada. Es combinen i descriuen les característiques d'impedància i de radiació. Els SDR s'introdueixen i es calibren per al funcionament de diversos elements i s'introdueixen els mètodes de calibratge per incerteses de fase i amplitud. El rendiment global del sistema es prova mitjançant diferents algorismes de formulació de feixos i algorismes de direcció d'estimació d'arribada. Els resultats de la mesura mostren que el sistema és fiable. S'aconsegueix un model de beamformació amb bona resolució i un rebuig elevat de la interferència. La estimació de la direcció d'arribada és precisa. / [CA] La tecnología de matriz en fase hizo una rotación en la industria del radar hace décadas. Hoy en día, la matriz en fase, o formación de haz, se está convirtiendo en una necesidad para la comunicación digital. La explotación de la formación de haz ayudaría a reducir el consumo de energía general de las estaciones base y el equipo del usuario. También permitirá que el servicio brinde datos mucho más altos y mejore la calidad del servicio. La investigación sobre la formación y comunicación de haces digitales requiere un conjunto de antenas y hardware compatible. El hardware debe ser capaz de manejar diferentes escenarios y enfoques para problemas de comunicación móvil. Hay varios sistemas utilizados para la investigación de conformación de haz, especialmente para la comunicación móvil. Estos sistemas sufren de varias deficiencias. Son costosos de implementar, no adaptativos y fijos a una arquitectura relacionada con cierto algoritmo de conformación de haz o con un número de elementos de arreglo fijo. En esta tesis, se propone un nuevo sistema matricial por fases. Este sistema podría ser explotado para la investigación en comunicaciones móviles o problemas de radar. Está compuesto por un conjunto de antenas planas de 8x1, canales de conversión de RF a banda base y procesador de banda base. La formación de haz y la estimación de DOA se realizan en muestras digitales de banda base. Esto proporciona al sistema dinamismo con respecto a los algoritmos probados. Para ese propósito, las tarjetas SDR ágiles se utilizan para adquirir señales de la red de antenas y convertirlas en flujos de datos digitales. Los flujos de datos se procesan en un procesador de banda base basado en FPGA. Además de ser de bajo costo y asequible para los pequeños institutos de investigación e investigaciones independientes, el sistema se puede ajustar para llevar más elementos de la red de antenas. El conjunto monopolo plano 8x1 está diseñado, simulado y medido. La correspondencia de impedancia y las características de radiación se representan y describen. Los SDR se introducen y se calibran para la operación de elementos múltiples y se introducen los métodos de calibración para las incertidumbres de fase y amplitud. El rendimiento general del sistema se prueba mediante diferentes algoritmos de conformación de haz y algoritmos de estimación de la dirección de llegada. Los resultados de las mediciones muestran que el sistema es confiable. Se logra una conformación de haz con buena resolución y alto rechazo de interferencia. Dirección de estimación de la llegada es precisa. / [EN] Phased array technology made a turnover in radar industry decades ago. Nowadays, phased array, or beamforming, is becoming a necessity for digital communication. Exploiting beamforming would help in reducing the overall power consumption of base stations and user equipment. It will also enables the service to provide much higher datarates and enhance the quality of service. Research on digital beamforming and communication requires antenna array and compatible hardware. The hardware should be capable of handling different scenarios and approaches for mobile communication problems. There are several systems used for beamforming research especially for mobile communication. These systems suffer from several deficiencies. They are either expensive to implement, not adaptive and fixed to an architecture related to certain beamforming algorithm or with fixed array elements number. In this thesis, a new phased array system is proposed. This system could be exploited for research in mobile communication or radar problems. It is composed of 8x1 planar antenna array, RF to baseband conversion channels and base band processor. Beamforming and DOA estimation is done on base band digital samples. This provides the system with dynamicity regarding tested algorithms. For that purpose, agile SDR boards are used to acquire signals from antenna array and convert them to digital data streams. Data streams are then processed in an FPGA based base band processor. In addition to being low in cost and affordable by small research institutes and freelancing researches, the system can be adjusted to carry more antenna array elements. The 8x1 planar monopole array is designed, simulated and measured. Impedance matching and radiation characteristics are plotted and described. SDRs are introduced and calibrated for multi-element operation and calibration method for phase and amplitude uncertainties are introduced. Overall system performance is tested by different beamforming algorithms and direction of arrival estimation algorithms. Measurement results show that the system is reliable. Beamforming with good resolution and high interference rejection is achieved. Direction of arrival estimation is accurate. / Haroun, MH. (2019). 8×1 Antenna Array System for Uplink Beamforming in LTE-A and 5G NR [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/129852

Phased microphone arrays are valuable tools for aeroacoustic measurements that can measure the directivity of multiple acoustic sources. However, when deployed in closed test-section wind tunnels, the acoustics suffer due to intense pressure fluctuations contained in the wall-bound turbulent boundary layer. Furthermore, phased microphone arrays require many sensors distributed over a large aperture to ensure good spatial resolution over a wide frequency range. Microphone arrays of such large count are not always feasible due to constraints in space and cost. This thesis describes an alternative approach for measuring single broadband acoustic sources that uses an acoustic metasurface. The metasurface is comprised of a meandering channel of quarter-wave cavities and an array of equally spaced half-wave open through-cavities. A series of tests were conducted in Virginia Tech's Anechoic Wall-Jet Tunnel where combinations of a wall-bound turbulent jet-flow and a single broadband acoustic source were used to excite the metasurface and produce acoustic surface waves. Measurements of the acoustic surface waves were performed using two methods: a pair of traversing microphones scanning the pressure field along the length of the metasurface 0.25 mm beneath its bottom face, and an array of unequally spaced microphones embedded inside the metasurface. Spectral analysis on the measurements revealed that the inclusion of multiple through-cavities leads to constructive reinforcement of select acoustic surface waves as a function of the acoustic source location. In the case of the embedded microphones, acoustic beamforming was applied in order to extract spatial information. This reinforcement was observed during measurements made with both flow and acoustic excitation, up to Wall-Jet Tunnel nozzle exit speeds of 40 m/s beyond which it was no longer seen. A series of quiescent measurements made with a range of speaker locations constituted a calibration for the metasurface which was used to locate an unknown broadband acoustic source within an The Root-Mean-Square (RMS) error of 1.06 degrees. / Master of Science / Phased microphone arrays are valuable tools for aeroacoustic measurements that can measure the directivity of multiple acoustic sources within a sound field. When used in conjunction with signal processing techniques, such as delay-and-sum beamforming, a researcher or engineer can obtain an intuitive view of the sound field and distinguish between multiple sources over a wide frequency range. However, these microphone arrays often utilize dozens of microphones which raises the array's complexity and cost. Furthermore, when a phased microphone array is mounted flush to the wall of a wind tunnel test section, it is submerged under a turbulent boundary layer which imposes intense pressure fluctuations on the microphones making it difficult to identify acoustic sources. Boundary layers form at the interface between a fluid and solid interface. This thesis describes experimentation performed in the Virginia Tech Anechoic Wall-Jet Tunnel on a new type of pressure sensing microphone array that leverage acoustic metamaterial technology. The acoustic metamaterial shields the microphones from the flow, lessening the influence of the turbulent boundary layer on the measurement. The focus in this thesis is on the novel array's ability to locate a single broadband acoustic source using as few as six microphones. The metasurface was installed in the Wall-Jet Tunnel test plate such that an array of evenly spaced through-cavities are flush to the surface. The through-cavities communicate the pressure field on top of the test surface to a meandering channel of interconnected closed cavities below. Near the resonant depth frequencies of the closed cavities, acoustic surface waves form which are evanescent pressure waves that are bound to the surface or structure that support them. The interference between the acoustic surface waves generated at each through-cavity leads to reinforced acoustic surface waves which are sensitive to the direction of a broadband source. In all, an acoustic metamaterial was tested under a variety of conditions such as: Wall-Jet Tunnel flow speed, speaker location, and the number of through-cavities open. The performance of the novel array and future plans are discussed.

The recent years have witnessed an unprecedented growth in the number of connected devices and amount of bandwidth required by the multiple services offered by wireless devices. The current 5G standard addresses such issues by adopting higher carrier frequencies and antennas with a large number of radiating elements. The former solution enables to exploit larger bandwidths in the millimeter-wave (mmWave) portion of the spectrum, while the latter one allows access points to serve an increasingly higher number of users. Both find realization in the Multiple-Input-Multiple-Output (MIMO) antenna systems with their enhanced beamforming capabilities. While the adoption of the hybrid digital-analog beamforming architecture lightens the overall system complexity, the need of miniaturized, high-performance and broadband hardware components is still an open issue. Passive Radio Frequency (RF) components in MicroElectroMechanical-Systems technology (RF-MEMS) offer notable and broadband electrical performances, while maintaining the marked miniaturization required for the hardware to be employed in the MIMO antennas, characterizing the current and future telecommunications scenario. Whilst numerous examples of single RF-MEMS switches, attenuators and phase shifters are available in the literature since about two decades, still limited attention is dedicated to the development of MEMS-based multi-device monolithic networks embedding such devices. High-performance RF-MEMS networks of this kind could represent the base of future MIMO beamforming architectures. Given such a context, the fundamental core of this thesis is the design and the realization of ad hoc RF-MEMS devices to be integrated in a reconfigurable monolithic module, operating in the realistic scenario of the mm-Wave portion of the spectrum allocated to 5G in Europe (24.25–27.5 GHz). The resulting devices consist in a 3-bit attenuator, three 1-bit phase-shifting cells and a Single-Pole-Double-Throw (SPDT) switch, each relying on membranes featuring a reduced actuation voltage, in the 5–9 V range, for an easier interfacing with electronics based on Complementary Metal–Oxide–Semiconductor (CMOS). To this purpose, the ad hoc designed MEMS switching membranes, along with prototypes of the building blocks to be embedded in the final module, are designed, optimized and fabricated. The experimental measurements performed on the prototypes of membranes (i.e. micro-switches), attenuation cells, optimized resistors and a phase shifter are compared to FEM-based (Finite Element Method) simulated results. Such comparison validates the simulation approach, in both the electromagnetic and the electro-mechanical domains, by which the proposed module is then designed and optimized in its final layout. To the best of our knowledge, this project is among the first to investigate the development of a monolithic module, entirely based on RF-MEMS passives, implementing both the attenuation and the phase shifting functionalities that can be employed in hybrid beamforming architectures at each antenna element. More in detail, the module features at least 25 attenuation and phase shifting states, from -5.39 dB to -13.51 dB by variable steps, and from 10.59° to 158.46°, respectively. Concerning the SPDT switch, satisfying electrical performances have been demonstrated in terms of return loss (<-10 dB), insertion loss (<-1.2 dB) and isolation (<-25 dB) over the 0–30 GHz interval. Despite their increased complexity, appealing results have marked the proposed attenuator and the phase-shifting cells, whose return and insertion losses are always better than -10 dB and -3 dB, respectively, along the frequency interval of interest. With an overall footprint not exceeding 9.51x3.35 mm2, the designed module effectively combines the miniaturization, broadband, and linear electrical behavior of RF-MEMS, making it a suitable candidate for the MIMO antennas of the current and future telecommunications scenario.

Milieu où les ultrasons se propagent environ 10% plus rapidement qu’au sein des tissus environnants, le cristallin est connu pour être la source majeure d’aberrations de phase du milieu oculaire. De fait, l’échographie ophtalmique trans cornéenne est affectée par ses effets qui se manifestent sur les B-scans par une dégradation marquée de la résolution spatiale et du contraste, accompagnée de plus, d’importantes distorsions, particulièrement notables au niveau du fond de l’œil. Face à ce problème et en vue de l’arrivée prochaine de barrettes US HF dans la pratique ophtalmologique, un beamforming adapté a été développé au cours de cette thèse. Basé sur un lancer de rayon à 2 points fixes, il permet le calcul de délais de focalisation qui compensent les aberrations induites par le cristallin, en prenant en compte les effets réfractifs à son interface avec les humeurs. Les résultats obtenus in vitro et ex vivo avec une barrette 20MHz et un échographe de recherche (ECODERM) sont rapportés. / In ophthalmic ultrasonography the crystalline lens is known to be the main source of phase aberration, as ultrasounds (US) propagate about 10% faster than in the surrounding intra-ocular medium. Hence, it impairs significantly both spatial and contrast resolution of axial B-scans, and in addition causes important distortion, especially on the ocular fundus. To deal with this issue and in view of the next coming of US arrays in ophthalmologic practice, we developed in this thesis an adapted beamforming (BF) free from crystalline lens aberrations. It lies on a two point ray tracing approach to compute focusing delays that take into account crystalline lens aberrations including refraction at the interface. Initially developed considering a uniform US velocity in the lens, the adapted BF has been extended to consider the velocity gradient that exists in the real lens. In vitro and ex vivo results obtained with a 20 MHz linear array driven by a US research scanner (the ECODERM) are reported.

This thesis contains design of beamforming network designed for passive radar antennas. The first part contains theory of passive radars and beamforming networks. The next part implies design of beamforming network at the block digram level. Then are choosed circuits for amplitude and phase control, including the design of control communication. It follows by realization of IQ phase shifter and his automatic measurement. Based on this results is phase shifter adjusted and PCB of 2x2 beamforming network is designed. Last part includes design of control application (Matlab) and control program for STM32F407VG microcontroller.