Diseño de una antena multibanda basada en fractales para redes móviles inalámbricas de banda ancha en las frecuencias de 0.9, 2.4 y 3.5 GHz

La tesis que se presenta a continuación tiene como objetivo el diseño de una antena multibanda de tipo fractal, capaz de operar en las frecuencias de 0.9, 2.4, y 3.5GHz definidas para los estándares de GSM, Wi-Fi y Wi-Max. Con tal fin, se llevan a cabo los siguientes pasos: Inicialmente se hace un estudio de las propiedades matemáticas de las geometrías empleadas, y del método numérico adecuado para el análisis de este tipo de antenas. Posteriormente se analizan y modelan matemáticamente las características de algunas antenas pre-fractales reportadas en la literatura, para luego proponer un modelo de antena que pueda operar en las frecuencias establecidas. A partir de la nueva antena, se proponen y realizan ciertas mejoras por medio de soluciones numéricas, obtenidas mediante simulación. Para finalizar se corroboran los resultados de forma experimental. Como conclusión, se obtiene una metodología que hace posible obtener una antena multibanda cuyas bandas se adaptan en las frecuencias elegidas por el diseñador. IMaestrí

Multi-antenna 3D pattern design for millimeter-wave vehicular communications

The transformation of the automotive industry towards ubiquitous connection of vehicles with all kind of external agents (V2X) motivates the use of a wide range of frequencies for several applications. Millimeter-wave (mmWave) connectivity represents a paramount research field in which adequate geometries of antenna arrays must be provided to be integrated in modern vehicles, so 5G-V2X can be fully exploited in the Frequency Range 2 (FR2) band. This paper presents an approach to design mmWave vehicular multi-antenna systems with beamforming capabilities considering the practical limitations of their usage in real vehicular environments. The study considers both the influence of the vehicle itself at radiation pattern level and the impact of the urban traffic on physical layer parameters. Connectivity parameters such as Signal-to-Interference-plus-Noise Ratio (SINR) and outage probability are optimized based on the array topology. A shaped beam in the vertical plane based on three preset radiating elements is proven to be robust enough against self-scattering effects on the vehicle body. Regarding the horizontal geometry, four panels on the roof's edges provide good coverage and link quality. The number of horizontal antennas per panel tightly depends on the required values of the link quality metrics, potentially leading to a non-uniform geometry between sides and front or back panels.This work was partly funded by the Spanish Ministerio de Economía y Competitividad under the projects PID2019-107885GB- C31 and MDM2016-0600, the Catalan Research Group 2017 SGR 219, and “Industrial Doctorate” programme (2018-DI-084). The Spanish Ministry of Education contributes via a predoctoral grant to the first author (FPU17/05561).Peer ReviewedPostprint (published version

Reconfigurable dual-polarized beam-steering broadband antenna using a crossed-strips geometry

In this letter, a reconfigurable dual-polarized broadband antenna with beam-steering capabilities using a parasitic layer is proposed for 5G new radio (NR) frequency range 1 (FR-1) applications. The antenna is a dual-port aperture-stacked patch structure with symmetrical orthogonal (horizontal and vertical) currents. The beam-steering is achieved by a pair of reconfigurable cross-shaped parasitic strips, which bestow the antenna three main beam directions θ = { ~ -25 ° ,0 ° , ~ 25 ° }, Ψ = {0 ° } with pointing and gain (7 dB) stability across a 30% impedance bandwidth (S 11 , S 22 <; -10 dB) from 3.2 - 4.3 GHz for both ports/polarizations. A prototype of the antenna is manufactured and measured demonstrating results in accordance with simulation expectations.This work was supported in part by Colombian “Departamento Administrativo de Ciencia, Tecnología e Innovación” Colciencias through convocatoria 727 of 2015 scholarship, and in part by the Spanish “Comision Interministerial de Ciencia y Tecnologia” (CICYT) under Projects TEC2013-47360-C3-1-P/AEI/10.13039/501100011033, TEC2016-78028-C3- 1-P/AEI/10.13039/501100011033, and MDM2016-0600, and Catalan Research Group 2017 SGR 219.Peer ReviewedPostprint (author's final draft

Design of a multiport frequency reconfigurable antenna suitable for IMT-advanced communications systems

This thesis tackles the design, manufacture and validation of multi-port and frequency reconfigurable antennas intended for advanced communications applications. The main accomplishments of this thesis are: Extension of the AMDSR© optimize package to efficiently deal with multiobjective and 3D structures. Broadband and nonlinear switch characterization. Study of novel planar multi-port antennas. Manufacturing of 3D antennas involving validation of a low cost material characterization technique at RF frequencies, techniques to control dielectric permittivity of 3D printed materials, and validation of alternatives for manufacturing 3D antennas. Design, validation, and manufacturing of a 3D pixellated antenna concept. Calculation of the currents on the switches of a parasitic layer antenna, design of a broadband antenna based on parasitic layer concept, development of a low complexity beam-steerable sub-array for millimeter waves, non-linear characterization of a parasitic layer based antenna element. Implementation of software defined radio based tests for antenna validation.Esta tesis aborda el diseño, fabricación y validación de antenas multipuerto reconfigurables en frecuencia para aplicaciones en sistemas de comunicaciones avanzados. Los principales logros de esta tesis son: Extensión del paquete de optimización de AMDSR© para tratar eficientemente con problemas de optimización multiobjetivo y estructuras 3D. Caracterización de interruptores en banda ancha y de sus parámetros no lineales. Estudio de antenas planares multipuerto. Fabricación de antenas 3D incluyendo la validación de una técnica de bajo costo para la caracterización de materiales en RF, estudio de técnicas para controlar la permitividad relativa de materiales impresos en 3D, y la validación de alternativas para la construcción de antenas 3D. Diseño, validación y manufactura de un concepto de antena 3D pixelada. Cálculo de las corrientes en los interruptores de una capa parásita para antenas, diseño de una antena de banda ancha basada en capa parásita, desarrollo de un sub-arreglo con haz dirigible de baja complejidad para ondas milimétricas. Implementación de pruebas de validación de antenas en plataformas de radio definida por software.Universidad Nacional de Colombia, ColcienciasConvocatoria 727 de 2015 - Doctorados nacionalesLínea de Investigación: Computación aplicadaDoctorad

Sistema de Encriptación con Wavelets y Caos

Reconstrucción de la señal f a partir de la matriz de coeficientes que se obtiene cuando se aplica la CWT.PregradoIngeniero Electrónic

X-parameters based characterization of PIN diodes for reconfigurable antenna assessment

This contribution presents the non-linear characterization up to 50 GHz of a PIN diode commonly used as switch for reconfigurable devices at microwave applications. Non-linear models are extracted by means of X-parameter measurements supported on accurate calibration and de-embedding procedures. Results are validated by S-parameter measurements in the low power signal regime and by harmonic measurements in the large signal regime. The use of these models for reconfigurable antennas assessment is discussed.This work was supported by the Spanish “Comisión Interministerial de Ciencia y Tecnología” (CICYT) under projects TEC2013-47360-C3-1-P, TEC2016-78028-C3-1-P and MDM2016-O6OO, and Catalan Research Group 2017 SGR 219, and by the Colombian “Departamento Administrativo de Ciencia, Tecnología e Innovación” (Colciencias) through ”Convocatoria 727 de 2015” scholarship.Peer ReviewedPostprint (published version

Study on beamforming V2I scenarios for sub-6 GHz and mmWave channels

The study of the wireless channel between a hybrid massive MIMO Base Station (BS) and a vehicular platform is proposed. Several multi-antenna geometries and MIMO architectures in both vehicle and BS are numerically modeled and compared. Different metrics are used for the assessment of the system performance, including channel capacity, in two frequency bands, sub-6 GHz (5.9 GHz) and millimeter-wave (mmWave) (26 GHz), under different propagation conditions. The use of beamforming techniques on the vehicle side is compared to conventional SISO and MIMO solutions. In the urban scenario used in the study, a 45° beamwidth circular array is able to enhance the single monopole performance up to 157% in capacity, and outperform MIMO 4×4 in most situations.This work was supported by the Spanish Comision Interministerial de Ciencia y Tecnología (CICYT) under projects TEC2016-78028-C3-1-P, MDM2016-0600, and Catalan Research Group 2017 SGR 219. The Spanish Ministry of Education contributes via a doctoral grant to the first author (FPU17/05561).Peer ReviewedPostprint (author's final draft

Design of minimum nonlinear distortion reconfigurable antennas for next-generation communication systems

Nonlinear effects in the radio front-end can degrade communication quality and system performance. In this paper we present a new design technique for reconfigurable antennas that minimizes the nonlinear distortion and maximizes power efficiency through the minimization of the coupling between the internal switching ports and the external feeding ports. As a nonlinear design and validation instance, we present the nonlinear characterization up to 50 GHz of a PIN diode commonly used as a switch for reconfigurable devices in the microwave band. Nonlinear models are extracted through X-parameter measurements supported by accurate calibration and de-embedding procedures. Nonlinear switch models are validated by S-parameter measurements in the low power signal regime and by harmonic measurements in the large-signal regime and are further used to predict the measured nonlinearities of a reconfigurable antenna. These models have the desired particularity of being integrated straightforwardly in the internal multi-port method formulation, which is used and extended to account for the power induced on the switching elements. A new figure of merit for the design of reconfigurable antennas is introduced—the power margin, that is, the power difference between the fed port and the switching elements, which combined with the nonlinear load models directly translates into nonlinearities and power-efficiency-related metrics. Therefore, beyond traditional antenna aspects such as port match, gain, and beam orientation, switch power criteria are included in the design methodology. Guidelines for the design of reconfigurable antennas and parasitic layers of minimum nonlinearity are provided as well as the inherent trade-offs. A particular antenna design suitable for 5G communications in the 3.5 GHz band is presented according to these guidelines, in which the specific switching states for a set of target performance metrics are obtained via a balancing of the available figures of merit with multi-objective separation criteria, which enables good control of the various design trade-offs. Average Error Vector Magnitude (EVM) and power efficiency improvement of 12 and 6 dB, respectively, are obtained with the application of this design approach. In summary, this paper introduces a new framework for the nonlinear modeling and design of reconfigurable antennas and provides a set of general-purpose tools applicable in cases beyond those used as examples and validation in this work. Additionally, the use of these models and guidelines is presented, demonstrating one of the most appealing advantages of the reconfigurable parasitic layer approach, their low nonlinearityThis research was supported by the Spanish “Comision Interministerial de Ciencia y Tecnologia” (CICYT) under projects TEC2013-47360-C3-1-P/AEI/10.13039/501100011033, TEC2016- 78028-C3-1-P/AEI/10.13039/501100011033, and MDM2016-O6OO, and Catalan Research Group 2017 SGR 219, and by the Colombian “Departamento Administrativo de Ciencia, Tecnología e Innovación” (Colciencias) through convocatoria 727 de 2015Peer ReviewedPostprint (published version

Millimeter-wave MIMO array measurement system for imaging and channel characterization

Millimeter-wave band offer unique characteristicsto obtain good spatial position and resolution of certain type oftargets. The aim of this paper is to study a near-field focusingtechnique applied to the imaging of different geometries, from ananalytical, numerical and experimental point of view. Millimeter-wave band scattering simulations are performed and comparedwith imaging reconstruction of experimental measurements,using a particular set-up and scenario. This work is a first stepto contribute to the growing need of sensing the environment andsurrounding objects of moving devices, such as new generationvehicles, in a clear and robust way with respect to other formsof sensing.This work was supported by the Spanish Ministry of Education and Science under projects 2019-107885GB-C31,TEC2016-78028-C3-1-P, TEC2016-78028-C3-2-P, TEC2016-78028-C3-3-P, MDM2016-0600, the Catalan Research Group 2017 SGR 219 and by the European FEDER funds. The Spanish Ministry of Education contributes via apredoctoral grant to the first author (FPU17/05561).Peer ReviewedPostprint (published version