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In this paper, we examine the potential for a reconfigurable intelligent surface (RIS) to be powered by energy harvested from information signals. This feature might be key to reap the benefits of RIS technology's lower power consumption compared to active relays. We first identify the main RIS power-consuming components and then propose an energy harvesting and power consumption model. Furthermore, we formulate and solve the problem of the optimal RIS placement together with the amplitude and phase response adjustment of its elements in order to maximize the signal-to-noise ratio (SNR) while harvesting sufficient energy for its operation. Finally, numerical results validate the autonomous operation potential and reveal the range of power consumption values that enables it., This work was supported by the European Commission’s Horizon 2020 research and innovation programme ARIADNE (No. 871464), the Luxembourg National Research Fund (FNR) under the CORE project RISOTTI (ref. 14773976), and the Digital Futures Center., Peer Reviewed, Postprint (author's final draft)

Next-generation cellular networks, i.e., beyond fifth generation (B5G) and sixth generation (6G) networks, aim at significantly increasing capacity by deploying a massive number of small cells (SCs) and leveraging millimeter wave (mmWave) links that have large bandwidth availability. However, as optical connections to a large number of base stations (BSs) are not cost effective, wireless backhaul (BH) links may be used to connect SCs to the core network using mmWave frequencies and forming multihop mesh BH paths. While very flexible in deployment, the uncertainty in user demand, which varies over time and place, makes network planning and management challenging. In this work, we propose novel algorithms to solve the joint problem of energy-efficient user association, BH traffic routing and BS/BH link on/off switching. We first formulate an exact model assuming user traffic demand uncertainty leveraging -robustness theory. As the model is intractable for large-scale instances, we develop a novel greedy robust heuristic (P-HEUR), which includes a robustifying step to effectively cope with demand uncertainty. Our evaluation demonstrates that P-HEUR provides robust and energy-efficient solutions quickly for different scenarios and traffic demand uncertainty levels, and it significantly outperforms state-of-the-art approaches while achieving up to 83% of the optimal capacity, even in the most demanding scenarios in terms of traffic load and demand uncertainty, with up to 200k times lower complexity., This research was supported by MCIN/AEI/10.13039/501100011033 and ERDF “A way of making Europe” under grant PGC2018-099945-BI00 (also responsible for the Article Processing Charges) and H2020-5G PPP 5G-COMPLETE (grant agreement 871900). All authors approved the version of the manuscript to be published., Postprint (published version)

The millimeter waves (mmWave) bands, considered to support the forthcoming generation of mobile communications technologies, have a well-known vulnerability to blockages. Recentworks in the literature analyze the blockage probability considering independence or correlation among the blocking elements of the different links. In this letter, we characterize the effect of blockages and their correlation on the ergodic capacity. We carry out the analysis for urban scenarios, where the considered blocking elements are buildings that are primarily parallel to the streets.We also present numerical simulations based on actual building features of the city of Chicago to validate the obtained expressions., This work was supported by Agencia Estatal De Investigación, Ministerio De Ciencia e Innovación, MCIN / AEI / 10.13039/501100011033 through the Project ROUTE56 - PID2019-104945GB-I00., Peer Reviewed, Postprint (author's final draft)

The mobile communications sector has seen tremendous growth in recent years which has led to a huge demand for mobile data. This demand will require new technologies that can offer the sufficient capacity that the sector will need. One of these technologies is 5G that will improve positioning, with centimeter precision. First of all, the channel in the millimeter wave band is explained as the channel model used. The algorithm used to position and how it makes use of the channel sparsity is also explained. Afterwards, it is shown that the performance of the algorithm is good and comparing with the results obtained in the studied algorithm, it is observed that the effect of the reflections does not improve the positioning error. Likewise, it can be seen that the use of a more "realistic" simulator makes the error somewhat greater than for the case studied. Finally, the conclusions we have reached and some fields or improvements that can be implemented or investigated in the near future are explained., El sector de les comunicacions mòbils ha tingut un gran creixement durante els darrers anys que ha portat a una gran demanda de dades mòbils. Aquesta demanda requerirà de noves tecnologies que oferiran la capacitat suficient que el sector necessitarà. Una d'aquestes tecnologies és el 5G que millorarà el posicionament, amb 1 precisions de centímetres. Per començar, s'explica el canal a la banda de les ones mil·limètriques com el model de canal utilitzat. També s'explica l'algoritme utilitzat per a posicionar i com fa ús de la sparsity del canal. Després és demostra que el rendiment de l'algoritme és bo i comparant amb els resultats obtinguts en l'algoritme estudiat s'observa que l'efecte de les reflexions no millora l'error de posicionament. També es pot veure que l'ús d'un simulador més "realista" fa que l'error que es comet és més gran que pel cas estudiat Per acabar s'explica les conclusions a les que hem arribat i uns quants camps o millores que es poden implementar o investigar en un futur proper., El sector de las comunicaciones móviles ha tenido un gran crecimiento durante los últimos años que ha llevado a una gran demanda de datos móviles. Esta demanda requerirá de nuevas tecnologías que puedan ofrecer la capacidad suficiente que el sector necesitará. Una de estas tecnologías es el 5G que mejorará el posicionamiento, con una precisión de centímetros. Para empezar, se explica el canal en la banda de las ondas milimétricas como el modelo de canal utilizado. También se explica el algoritmo utilizado para posicionar y como hace uso de la sparsity del canal. Después se demuestra que el rendimiento del algoritmo es bueno y comparando con los resultados obtenidos en el algoritmo estudiado se observa que el efecto de las reflexiones no mejora el error de posicionamiento. Asimismo, se puede ver que el uso de un simulador más "realista" hace que el error cometido sea algo mayor que para el caso estudiado. Para acabar se explica las conclusiones a las que hemos llegado y algunos campos o mejoras que se pueden implementar o investigar en un futuro próximo.

La banda de frecuencias de ondas milimétricas (MMW), caracterizada por una elevada atenuación atmosférica y un gran ancho de banda disponible, se ha convertido de gran interés para aplicaciones de imágenes de radar de alta precisión. El desarrollo continuo de la tecnología de circuitos de microondas monolíticos integrados (MMIC) da lugar a la aparición de diferentes transceptores de radar comerciales (COTS) en esta banda de frecuencia, donde las antenas están totalmente integradas en el chip para evitar pérdidas en el sustrato. Las lentes se utilizan para corregir el frente de fase de estos chips mejorando la directividad y, por tanto, el rango de funcionamiento. Las lentes geodésicas, que pueden ser construidas utilizando sólo metales, ofrecen las propiedades atractivas de las lentes dieléctricas comunes sin sus pérdidas en el metarial. En este trabajo de fin de máster se ha diseñado una antena del tipo lente geodésica específica con propiedades de enfoque para mejorar las capacidades de imagen de radar del transceptor TRA-120-002 que trabaja en la banda ISM de 120 GHz. Se ha hecho un estudio de diferentes transiciones para los puntos singulares de la antena, minimizando reflexiones sin aumentar las aberraciones en la lente. En el trabajo se muestra un diseño optimizado de la apertura de la antena donde se utilizan corrugacions para mejorar el diagrama de radiación. Se ha diseñado también una pequeña antena de apertura con una metasuperfície de pines periódicos para maximizar la transmisión de energía entre el transceptor COTS y la lente. Finalmente, se ha añadido una metasuperfície basada en agujeros con simetría deslizada para evitar fugas entre las placas de la antena debido a posibles limitaciones en su fabricación. Los resultados muestran que se puede conseguir una antena de tipo lente de 5l de radio totalmente metálica con directividad superior a 19,5 dB y niveles de lóbulos secundários (SLL) entre -10,5 dB y -9,2 dB dentro de la banda de 119 GHz - 125,5 GHz, La banda de freqüències d'ones mil·limètriques (mmW), caracteritzada per una elevada atenuació atmosfèrica i un gran ample de banda disponible, ha esdevingut de gran interès per a aplicacions d'imatges de radar d'alta precisió. El desenvolupament continu de la tecnologia de circuits de microones monolítics integrats (MMIC) dona lloc a l'aparició de diferents transceptors de radar comercials (COTS) en aquesta banda de freqüència, on les antenes estan totalment integrades al xip per evitar pèrdues en el substrat. Les lents s'utilitzen per corregir el front de fase d'aquests xips millorant la directivitat i, per tant, el rang de funcionament. Les lents geodèsiques, que poden ser construïdes utilitzant només metalls, ofereixen les propietats atractives de les lents dielèctriques comuns sense les seves pèrdues en el material. En aquest treball de fi de màster s'ha dissenyat una antena del tipus lent geodèsica específica amb propietats d'enfocament per millorar les capacitats d'imatge de radar del transceptor TRA-120-002 que treballa a la banda ISM de 120 GHz. S'ha fet un estudi de diferents transicions per als punts singulars de l'antena, minimitzant reflexions sense augmentar les aberracions a la lent. En el treball es mostra un disseny optimitzat de l'obertura de la antena on s'utilitzen corrugacions per millorar el diagrama de radiació. S'ha dissenyat també una petita antena d'obertura amb una metasuperfície de pins periòdics per maximitzar la transmissió d'energia entre el transceptor COTS i la lent. Finalment, s'ha afegit una metasuperfície basada en forats amb simetria lliscada per evitar pèrdues entre les plaques de l'antena a causa de possibles limitacions en la seva fabricació. Els resultats mostren que es pot aconseguir una antena de tipus lent de 5l de radi totalment metàl·lica amb directivitat superior a 19,5 dB i nivells de lòbuls secundaris (SLL) entre -10,5 dB i -9,2 dB dins de la banda de 119 GHz - 125,5 GHz mentre que l'antena focalitza a 30 cm., The Millimiter Wave (mmW) frequency band, characterized by a high atmospheric attenuation and wide available bandwidth has become of big interest for high accuracy radar imaging applications. The continuous development of the Monolithic Microwave Integrated Circuit (MMIC) technology yields to the appearance of different commercial-off-the-shelf (COTS) radar transceivers at that frequency band, where the antennas are fully integrated into the chip. Lenses are being used to correct the phase front of those MMIC improving the directivity and therefore the operating range. Fully metallic geodesic lenses offer the attractive properties of common dielectric lenses without their material losses. In this master thesis, a specific water-drop geodesic lens antenna with focusing properties has been designed to enhance the radar imaging capabilities of the theTRA-120-002 transceiver working at the 120 GHz Industrial, Scientific and Medical (ISM) band. Different transitions for the antenna singular points have been studied to minimize reflections without increasing aberrations in the lens. An optimized design of a radiating flare is shown where corrugations are used to improve the antenna radiation pattern. A small feeding horn antenna with a bed-of-nails Electromagnetic Band-Gap (EBG) metasurface has been designed to maximize the energy transmission between the COTS transceiver and the lens. Finally, a glide-symmetric holey metasurface has been added to prevent leakage between the antenna plates due to manufacturing limitations. The results show that a fully metallic folded lens antenna with 5l radius can achieve directivities higher than 19.5 dB and side-lobe levels (SLL) between -10.5 dB and -9.2dB within the 119 GHz - 125.5 GHz band while having an image point located at 30cm from the antenna.

Within the framework of 5G, blockage effects occurring in the mmWave band are critical. Previous works describe the effects of blockages in isolated and multiple links for simple blocking objects, modeled with mathematical tools such as stochastic geometry and random shape theory. Our study uses these tools to characterize a scenario with N links, including the possible correlation among them in terms of blocking for several models of blocking objects. We include numerical evaluations highlighting that assuming independence among the links’ blocking elements is a too-brief simplification and does not accurately describe the real scenario. This paper also applies the formulation developed for the case of N links to optimize the relay positioning in mmWave cells for coverage enhancement, that is, to minimize the communication failure probability. We also show that both link budget and blockages affect the optimum positioning of the relays as they are both essential for successful transmission., The work presented in this paper has been funded through the projects 5G&B-RUNNER-UPC (Agencia Estatal de Investigación and Fondo Europeo de Desarrollo Regional, TEC2016-77148-C2-1-R / AEI/FEDER, UE) and ROUTE56 (Agencia Estatal de Investigación, PID2019- 104945GB-I00 / AEI / 10.13039/501100011033); and the grant 2017 SGR 578 (Catalan Government—Secretaria d’Universitats i Recerca, Departament d’Empresa i Coneixement, Generalitat de Catalunya, AGAUR)., Peer Reviewed, Postprint (published version)

In the millimeter waves (mmWave) bands considered for 5G and beyond, the use of very high frequencies results in the interruption of communication whenever there is no line of sight between the transmitter and the receiver. Blockages have been modeled in the literature so far using tools such as stochastic geometry and random shape theory. Using these tools, in this paper, we characterize the lengths of the segments in line-of-sight (LOS) and in non-line-of-sight (NLOS) statistically in an urban scenario where buildings (with random positions, lengths, and heights) are deployed in parallel directions configuring streets., This work has been funded through the projects 5G&B-RUNNER-UPC (Agencia Estatal de Investigacion and Fondo Europeo de Desarrollo Regional, TEC2016-77148-C2-1-R / AEI/FEDER, UE) and ROUTE56 (Agencia Estatal de Investigacion, PID2019-104945GB-I00 / AEI / 10.13039/501100011033); and the grant 2017 SGR 578 (AGAUR, Generalitat de Catalunya)., Peer Reviewed, Postprint (published version)

©2018 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works., Recently, a receive spatial modulation (RSM) for massive multiple-input-multiple-output operating in millimeter wave (mmWave) was introduced with the purpose of simplifying user terminal circuit by employing only one radio-frequency chain and attaining high spectral efficiency by exploiting the receive spatial dimension. However, when RSM is applied in a mmWave channel, it demands a challenging receive antenna selection (RAS) procedure. On the other hand, the power consumption at the transmitter side is high when a full digital (FD) precoder is envisioned. We consider the joint problem of RAS and precoder designs based low complexity hybrid architecture. For the sake of simplicity, we divide this problem into two subproblems. First, we design the RAS assuming FD precoder, and then, we design the hybrid precoder. We propose two novel and efficient RAS methods. First, we formulate the RAS as non-convex optimization problem. Then, we convert it into a convex optimization problem by introducing novel lower bounds and relaxing non-convex constraints. Second, we provide sequential algorithms that approach the optimal selection where we (add/remove) one (good/poor) antenna per iteration. We propose novel zero forcing hybrid precoder based convex optimization that maximizes the received power. We prove that the proposed precoder is optimal when the channel is highly spatially sparse. The proposed designs have been compared with the best known methods in terms of average mutual information and energy efficiency showing significant improvements., Peer Reviewed, Postprint (author's final draft)

©2017 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works., Macrocells are expected to be densely overlaid by small cells (SCs) to meet increasing capacity demands. Due to their dense deployment, some SCs will not be connected directly to the core network, and thus, they may forward their traffic to the neighboring SCs until they reach it, thereby forming a multihop backhaul (BH) network. This is a promising solution, since the expected short length of BH links enables the use of millimeter-wave (mmWave) frequencies to provide high-capacity BH. In this context, user association becomes challenging due to the multihop BH architecture, and therefore, new optimal solutions should be developed. Thus, in this paper, we study the user association problem aiming at the joint maximization of network energy efficiency (EE) and spectrum efficiency (SE), without compromising the user quality of service (QoS). The problem is formulated as an e-constraint problem, which considers the transmit energy consumption both in the access network, i.e., the links between the users and their serving cells, and the BH links. The optimal Pareto-front solutions of the problem are analytically derived for different BH technologies, and insights are gained into the EE and SE tradeoff. The proposed optimal solutions, despite their high complexity, can be used as a benchmark for the performance evaluation of user association algorithms. We also propose a heuristic algorithm, which is compared with reference solutions under different traffic scenarios and BH technologies. Our results motivate the use of mmWave BH, whereas the proposed algorithm achieves near-optimal performance., Peer Reviewed, Postprint (author's final draft)

Due to the dense small cell deployment to cope with the increased data traffic of fifth generation (5G) networks, the direct backhaul (BH) connection of all small cells to the core network becomes challenging. To that end, millimeter wave (mmWave) technology is a promising solution for cost-efficient high capacity small cell BH links. However, due to the severe signal attenuation at high frequencies, mmWave can provide good coverage only for short distances, thus favoring a multihop 5G BH architecture. In this context, where BH is expected to play a key role, traditional problems such as user association that impact both the network and user performance call for BH-aware strategies. Hence, in this paper, we study the user association problem aiming at the joint energy and spectrum efficiency maximization of the network, without compromising the user quality of service. The problem is formulated as a generalized assignment problem, which considers the capacity and energy consumption both in the access network and BH links. Provided that the considered problem is shown to be NP-hard, we employ optimization techniques to obtain an upper bound on system performance. We also propose a low complexity algorithm, which is shown to outperform the state-of-the-art while achieving near-optimal performance., Peer Reviewed, Postprint (published version)

©2014 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works., In this letter, a practical fabrication of a novel inhomogeneous gradient-index dielectric flat lens for millimeter-wave applications is presented. A previous theoretical design of a dielectric flat lens composed of different permittivity materials is now modeled and analyzed for a practical prototype fabrication and performance evaluation at 60 and 77 GHz. The measurement results at 60 GHz show that with the novel gradient-index dielectric flat lens antenna prototype, we can achieve up to 18.3 dB of broadside gain, beam-steering capabilities in both planes from -30 degrees to +30 degrees with around 15 dB of gain, and up to +/- 45 degrees with around 14 dB of gain, with low sidelobe levels. At 77 GHz, the performance evaluation shows that we can obtain up to 18.9 dB of broadside gain, beam-steering capabilities in both planes from -30 degrees to +30 degrees with around 17 dB of gain and low sidelobe levels, and up to +/- 45 degrees with around 15 dB of gain. This novel design leads to a low-cost, low-profile, and lightweight antenna solution, easy to integrate in a compact millimeter-wave wireless communication system., Peer Reviewed, Postprint (author's final draft)

This paper deals with mobility robustness in a context of ultra-dense deployments operating at the millimeter wave (mmW) band. In order to increase the threshold speed of user equipments (UEs) allowed at the small cell layer, we propose the use of selective Control/User-plane split combined with a noncoherent cooperative multi-point (CoMP) joint transmission (JT). This way, users at moderate speeds can also benefit from the new cell layer and improve their performance with respect to a pure macrocellular operation. The combination of this strategy with a fine tuning of the measurement gap interval allows reducing handover failure rates, which eventually translates into a throughput improvement. On the other hand, increasing the number of measurements leads to a higher UE power consumption, fact that has also been quantified and evaluated., Peer Reviewed, Postprint (published version)

[ANGLÈS] Currently, the usage of wireless devices and broadband communications is growing. As a consequence the research in how to implement high data rates in Radio over Fiber (RoF) links is becoming an interesting field to investigate. This Master Thesis examines two proposals for developing high capacity millimetre wave RoF systems. The first proposal is the Integrated Photonic Broadband Radio Access Units for Next Generation Optical Access Networks (IPHOBAC-NG) project. It proposes novel photonic radio access for Wavelength Division Multiple Access (WDMA) networks. The proposed Radio Access Unit (RAU) enables connections between optical fiber and E-band (60-90 GHz) wireless communications, avoiding the re/demodulation latencies due to the coherent heterodyne detection and optical up/down conversion using 90º optical Hybrids for Wavelength Division Multiplexing Passive Optical Networks (WDM-PON). This proposal presents an alternative to allocate wavelengths in optical fibers without needing to implement multiplexers and demultiplexers for separating each wavelength channel. The second proposal consists of an Adaptive and Cognitive RoF System (ACRoFS) using an Optically Controlled Reconfigurable Antenna (OCRA) and a broadband horn antenna for 28-38 GHz frequency band. The novel OCRA, which is examined in this thesis, enables to reconfigure the antenna properties for three different frequency bands; 28, 34 and 38 GHz bands. Moreover, this Master Thesis explains different blocks for implementing a digital coherent optical receiver in order to understand how a coherent receiver is able to recover the received signal. This Master Thesis also examines the experimental setup and the results obtained for testing and characterizing two bidirectional V-band (57-63 GHz) transceivers., [CASTELLÀ] Actualmente, el uso de dispositivos móviles y la necesidad de comunicaciones que requieren de gran ancho de banda están creciendo continuamente. Como consecuencia, la investigación sobre cómo implementar enlaces Radio over Fiber (RoF) de alta capacidad se está convirtiendo en un campo interesante a investigar. En esta Master Thesis se examinan dos propuestas para desarrollar sistemas de alta capacidad para enlaces de RoF transmitiendo a frecuencias de ondas milimétricas (30-300 GHz). La primera propuesta es el proyecto “Integrated Photonic Broadband Radio Access Units for Next Generation Optical Access Networks” (IPHOBAC-NG). Este proyecto propone una nueva solución para implementar accesos de radio fotónicos para redes con Wavelength Division Multiple Access (WDMA). La novedosa propuesta Radio Access Unit (RAU) permite conexiones entre fibra óptica y comunicaciones inalámbricas, en la banda de frecuencia E-band (60-90 GHz), evitando los retardos de la de/re-modulación de la señal ya que usa detección coherente heterodino y realiza la conversión up/down utilizando un hibrido óptico de 90º para Wavelength Division Multiplexing Passive Optical Networks (WDM-PON). Esta propuesta es una alternativa para asignar las longitudes de onda en la fibra óptica sin necesidad de implementar multiplexores y de-multiplexores para asignar/separar cada longitud de onda. La segunda propuesta consiste en un sistema adaptativo y cognitivo para RoF, “Adaptive and Cognitive RoF System” (ACRoFS), utilizando una Antena Reconfigurable Controlada Ópticamente (OCRA) y una antena de gran ancho de banda (Broadband horn antenna) para la banda de frecuencia entre 28-38 GHz. La novedosa OCRA, la cual se examina en esta thesis, permite reconfigurar las propiedades de la antena para tres frecuencias distintas; 28, 34 y 38 GHz. Además, en esta Master Thesis se presentan los diferentes bloques para implementar un receptor óptico coherente digital, los cuales nos dan una visión de cómo un rec, [CATALÀ] Actualment, l’ús de dispositius mòbils i la necessitat de comunicacions que requereixen gran ample de banda estan creixent contínuament. Com a conseqüència, la investigació sobre com implementar enllaços Radio over Fiber (RoF) d’ alta capacitat s’ està convertint en un camp interessant a investigar. En aquesta Master Thesis s’examinen dos propostes per desenvolupar sistemes d’alta capacitat per RoF transmeten a freqüències d’ones mil·limètriques (30-300 GHz). La primera proposta és el projecte “Integrated Photonic Broadband Radio Access Units for Next Generation Optical Access Networks” (IPHOBAC-NG). Aquest projecte proposa una nova solució per implementar accessos de radio fotònics per a xarxes amb Wavelength Division Multiple Access (WDMA). La novadora proposta Radio Access Unit (RAU) permet connexions entre fibra òptica i comunicacions wireless, a la banda de freqüència E-band (60-90 GHz), evitant els retards de la de/re modulació de la senyal ja que utilitza detecció coherent heterodina i realitza la conversió up/down utilitzant un híbrid òptic de 90º per a Wavelength Division Multiplexing Passive Optical Networks (WDM-PON). Aquesta proposta és una alternativa per assignar longituds d’ona a la fibra òptica sense necessitat d’implementar multiplexors i de-multiplexors per assignar/separar cada longitud d’ona. La segona proposta consisteix en un sistema adaptatiu i cognitiu per a RoF, “Adaptive and Cognitive RoF System” (ACRoFS), utilitzant una Antena Reconfigurable Controlada Òpticament (OCRA) i una antena de gran ample de banda (Broadband horn antenna) per a la banda de freqüències entre 28-38 GHz. La novadora OCRA, la qual s’ examina en aquesta thesis, permet reconfigurar les propietats de l’antena per a tres freqüències diferents; 28, 34 y 38 GHz. A més a més, en aquesta thesis es presenten els diferents blocs per implementar un receptor òptic coherent digital, els quals ens donen una visió de com un receptor coherent és capaç de recuperar la informac

In this paper, a practical fabrication of a dielectric flat lens for millimeter-wave applications is presented. A previous theoretical dielectric flat lens antenna design, consisting of a set of concentric rings with different permittivity values for each, is now modeled and analyzed for a practical prototype fabrication and preliminary performance evaluation at 75 GHz. Preliminary measurements show that with the dielectric flat lens antenna prototype we can achieve beam-steering capabilities from -30 to +30 with around 17 dB of gain, and up to ±45 beam-steering capabilities with around 15 dB of gain, with low side-lobe levels. This design also leads to a low-profile antenna configuration, easy to manufacture and low-cost, in order to integrate the whole structure in a compact millimeter-wave commercial wireless system., Peer Reviewed, Postprint (published version)

Silicon micromachined RF passive components such as washers, waveguide with 90 degree bends for 325-500 GHz band, and silicon-stacked blocks for W-band (75-110 GHz) GaAs power amplifiers have been designed, microfabricated, and characterized. Based on these results, we have successfully stacked several silicon micromachined wafers in order to build a Receiver-On-a-Chip (ROC) at 560 GHz. To the authors' knowledge, this is the first demonstration of an all integrated silicon micromachined receiver front-end at submillimeter wavelengths. In addition, we have developed silicon microlens antenna which is compatible with the current silicon micromachined ROC. We have also developed wafer-level microlens microfabrication technique., Peer Reviewed, Postprint (published version)

En esta tesis se han desarrollado los siguientes métodos numéricos para el análisis de estructuras planares, especialmente finline, en la banda de microondas y ondas milimétricas: -el método de las líneas con discretizacion uniforme y no uniforme. -el método de los elementos finitos aplicado al análisis de guías homogéneas e inhomogeneas. -el método de la matriz de lineas de transmisión tridimensional. -el método de la matriz se generalizada para el análisis de estructuras uniformes y discontinuidades planares. -el método del dominio espectral para el análisis de estructuras planares uniformes. -el método del circuito planar con corrección de la dispersión. Se ha elegido el método de la resonancia transversal generalizado como el mas idóneo para el análisis preciso y rápido de discontinuidades finline con un mínimo de recursos informáticos. Se ha desarrollado incluyendo el carácter singular de los campos en las aristas de la estructura, consiguiéndose minimizar el fenómeno de la convergencia relativa y obteniéndose resultados precisos con expansiones reducidas de las funciones modales que representan los campos, validándose los resultados obtenidos al analizar diversas estructuras con medidas experimentales., Postprint (published version)

There is an interest for climatology and meteorology to map hydrometeors, and in particular precipitation, both over the entire globe and across large defined regions. To achieve this goal at the proper spatial and temporal resolution which are required to satisfy the end users needs it has been proposed to use satellite based observations. This paper presents the results of a theoretical study aiming to the research of new concepts for the remote sensing of hydrometeors with emphasis on precipitation. The concept proposed is a Focused Wide band millimeter wave INTERferometer (WINTER-F) comprising a constellation of two small satellites, flying close to each other. The two satellites, which are phase synchronized by the GNSS (Global Navigation Satellite System) signals, perform near field interferometry by passive (radiometer) and active (radar) means. The study comprises the realization of laboratory experiments to check the validity of the theoretical models, Peer Reviewed, Postprint (published version)