Robust adaptive beamforming for MIMO monopulse radar

Researchers have recently proposed a widely separated multiple-input multiple-output (MIMO) radar using monopulse angle estimation techniques for target tracking. The widely separated antennas provide improved tracking performance by mitigating complex target radar cross-section fades and angle scintillation. An adaptive array is necessary in this paradigm because the direct path from any transmitter could act as a jammer at a receiver. When the target-free covariance matrix is not available, it is critical to include robustness into the adaptive beamformer weights. This work explores methods of robust adaptive monopulse beamforming techniques for MIMO tracking radar

Adaptive MIMO Radar for Target Detection, Estimation, and Tracking

We develop and analyze signal processing algorithms to detect, estimate, and track targets using multiple-input multiple-output: MIMO) radar systems. MIMO radar systems have attracted much attention in the recent past due to the additional degrees of freedom they offer. They are commonly used in two different antenna configurations: widely-separated: distributed) and colocated. Distributed MIMO radar exploits spatial diversity by utilizing multiple uncorrelated looks at the target. Colocated MIMO radar systems offer performance improvement by exploiting waveform diversity. Each antenna has the freedom to transmit a waveform that is different from the waveforms of the other transmitters. First, we propose a radar system that combines the advantages of distributed MIMO radar and fully polarimetric radar. We develop the signal model for this system and analyze the performance of the optimal Neyman-Pearson detector by obtaining approximate expressions for the probabilities of detection and false alarm. Using these expressions, we adaptively design the transmit waveform polarizations that optimize the target detection performance. Conventional radar design approaches do not consider the goal of the target itself, which always tries to reduce its detectability. We propose to incorporate this knowledge about the goal of the target while solving the polarimetric MIMO radar design problem by formulating it as a game between the target and the radar design engineer. Unlike conventional methods, this game-theoretic design does not require target parameter estimation from large amounts of training data. Our approach is generic and can be applied to other radar design problems also. Next, we propose a distributed MIMO radar system that employs monopulse processing, and develop an algorithm for tracking a moving target using this system. We electronically generate two beams at each receiver and use them for computing the local estimates. Later, we efficiently combine the information present in these local estimates, using the instantaneous signal energies at each receiver to keep track of the target. Finally, we develop multiple-target estimation algorithms for both distributed and colocated MIMO radar by exploiting the inherent sparsity on the delay-Doppler plane. We propose a new performance metric that naturally fits into this multiple target scenario and develop an adaptive optimal energy allocation mechanism. We employ compressive sensing to perform accurate estimation from far fewer samples than the Nyquist rate. For colocated MIMO radar, we transmit frequency-hopping codes to exploit the frequency diversity. We derive an analytical expression for the block coherence measure of the dictionary matrix and design an optimal code matrix using this expression. Additionally, we also transmit ultra wideband noise waveforms that improve the system resolution and provide a low probability of intercept: LPI)

Hybrid analog-digital processing system for amplitude-monopulse RSSI-based MiMo wifi direction-of-arrival estimation

We present a cost-effective hybrid analog digital system to estimate the Direction of Arrival (DoA) of WiFi signals. The processing in the analog domain is based on simple wellknown RADAR amplitude monopulse antenna techniques. Then, using the RSSI (Received Signal Strength Indicator) delivered by commercial MiMo WiFi cards, the DoA is estimated using the socalled digital monopulse function. Due to the hybrid analog digital architecture, the digital processing is extremely simple, so that DoA estimation is performed without using IQ data from specific hardware. The simplicity and robustness of the proposed hybrid analog digital MiMo architecture is demonstrated for the ISM 2.45GHz WiFi band. Also, the limitations with respect to multipath effects are studied in detail. As a proof of concept, an array of two MiMo WiFi DoA monopulse readers are distributed to localize the two-dimensional position of WiFi devices. This costeffective hybrid solution can be applied to all WiFi standards and other IoT narrowband radio protocols, such us Bluetooth Low Energy or Zigbee.This work was supported in part by the Spanish National Projects TEC2016-75934-C4-4-R, TEC2016-76465-C2-1-R and in part by Regional Seneca Project 19494/PI/14

Diseño y aplicaciones de sistemas de antenas inteligentes para redes inalámbricas en el contexto de la internet de las cosas

[SPA] Esta tesis doctoral se presenta bajo la modalidad de compendio de publicaciones. Las antenas de onda de fuga (LWA) consisten en una estructura de guía de onda que permite la fuga de parte de la potencia a lo largo de la estructura. Por esta razón, la radiación de la antena se produce por la fuga de energía. Para producir una radiación coherente, es necesario controlar esta tasa de radiación a lo largo de la estructura radiante. Así, ajustando con precisión la tasa de radiación, se controla la forma del diagrama de radiación. Las LWAs han sido ampliamente estudiadas por la comunidad científica debido a sus ventajas, tales como, red de alimentación simple, alta directividad y escaneo en frecuencia pasivo. Sin embargo, presentan ciertas desventajas entre las cuales, la más importante a destacar es el efecto de beam-squinting. Éste se produce por la propiedad dispersiva inherente a este tipo de antenas. Además, presentan dificultades a la hora de generar radiación coherente en las direcciones broadside y endfire, aumentando la complejidad del diseńo para la radiación en dichas direcciones. Las LWA han sido relativamente poco utilizadas en aplicaciones prácticas hasta la fecha, a pesar de sus ventajas. Las pocas aplicaciones en las que se han utilizado son los radares de onda continua modulada en frecuencia y los sistemas de enfoque controlado en frecuencia de campo cercano. Esta tesis propone el uso de las LWAs en aplicaciones prácticas aprovechando las ventajas mencionadas anteriormente y teniendo en cuenta los inconvenientes de este tipo de antenas para que su uso no sea limitado. Recientemente, las LWAs han sido propuestas para aplicaciones de localización de bajo coste, ya que permiten el diseńo de estructuras planas con haces directivos. Además, debido al aumento exponencial del uso de la tecnología, es necesario encontrar nuevas tecnologías para una transmisión de datos mayor, más rápida y más eficiente, manteniendo bajos costes de fabricación. Por lo tanto las LWAs pueden ser una solución crucial al mezclar bajos costes de fabricación, alta integrabilidad en diferentes sistemas debido a su tecnología impresa planar y alta directividad al mismo tiempo que se aprovecha su característica dispersiva que proporciona un escaneo pasivo en frecuencia. En este contexto, la principal aportación de esta Tesis consiste en el estudio, análisis, diseńo e integración de LWAs en aplicaciones reales y prácticas. Esta Tesis presenta las siguientes tres contribuciones principales, definidas en los tres bloques principales de este documento: • Estudio y análisis de LWAs para su uso en sistemas de estimación de dirección de llegada basados en técnicas de amplitud de monopulso. Comparar las características y prestaciones de las LWAs junto con las antenas comerciales más utilizadas. Para ello, diseńar y fabricar las HWM-LWAs con el fin de comparar sus prestaciones con las antenas de panel adquiridas comercialmente. Dado que cada aplicación requiere el diseńo de una HWM-LWA nueva y diferente, estudiar y proponer una técnica eficiente de análisis y diseńo de antenas para obtener fácilmente diagramas de radiación monopulso escaneados en frecuencia. • Una vez analizado que las HWM-LWA son una solución factible para su uso en aplicaciones reales de localización debido a sus diversas ventajas. Integrar las HWM-LWAs diseńadas en sistemas digitales para estimación del ángulo de llegada en interiores. Por lo tanto, diseńar, desarrollar, configurar e integrar las LWAs en diferentes sistemas basados en las bandas de frecuencia Wi-Fi ISM de 2,4 GHz y 5 GHz. Finalmente, comparar los resultados de estimación obtenidos con otras soluciones propuestas para corroborar que los LWAs pueden ser utilizados en aplicaciones reales. • Asimismo, debido a su bajo coste de fabricación y a su principal propiedad de escaneo en frecuencia. Ampliar el uso de las LWAs para la localización angular en redes de sensores inalámbricas (WSN) utilizando la banda de frecuencias UHF de 900 MHz. Utilizando así etiquetas RFID pasivas. También estudiar su aplicabilidad en WSNs utilizando etiquetas LoRa activas. Este documento se presenta como una Tesis por compendio, por lo que se presentarán y explicarán brevemente los 4 artículos de revistas que se han publicado durante el programa de doctorado. Además, también se presentarán algunos artículos de conferencias y otros trabajos en revisión para exponer algunas de las investigaciones que no han sido publicadas en revistas hasta la fecha de depósito de tesis. El documento está organizado como se indica a continuación: En la Introducción, se presenta una contextualización del estado del arte y una explicación rigurosa sobre las LWAs y las aplicaciones anteriormente mencionadas. Las dos partes siguientes se vi dedican a presentar y explicar brevemente los trabajos publicados que contribuyen a esta Tesis. En la parte II, se presentan los cuatro artículos que conforman el compendio. Esto es, el análisis de las LWAs para la estimación de la dirección del ángulo de llegada y la integración de las LWAs en sistemas de localización digital usando el protocolo Wi-Fi en el Capítulo 1, la banda de frecuencias ISM UHF 900 MHz se utiliza junto con los HWM-LWAs en el Capítulo 2, luego se implementa en un sistema en tiempo real para la estimación de la dirección de llegada de múltiples tags pasivos en el Capítulo 3 y la integración de LoRa en el Capítulo 4. Finalmente, en la Parte III, se discuten las conclusiones generales y las futuras líneas de investigación. [ENG] This doctoral dissertation has been presented in the form of thesis by publication. Leaky-Wave Antennas (LWA) consist on a waveguide structure which allows the leakage of part of the power along the structure. For this reason, the radiation of the antenna is produced by the leakage of power. In order to produce coherent radiation, it is necessary to control this leakage rate along the radiating structure. Thus, precisely adjusting the leakage rate, the shape of the radiation pattern is controlled. LWAs have been widely studied by the scientific community due to their advantages, such as, simple feeding network, high directivity and passive frequency-scanning performance. However, they present certain disadvantages among which, the most important to highlight is the beam-squinting effect. TThis is due to the inherent dispersion property of this type of antenna. In addition, LWAs present difficulties when generating coherent radiation in broadside and endfire directions, increasing the complexity of the design for radiation in these directions. LWAs have been relatively unused in practical applications to date, despite of their benefits. The few applications in which they have been used are frequency modulated continuous wave radars and near-field frequency controlled focusing systems.This thesis proposes the use of LWAs in practical applications by exploiting the advantages mentioned above while taking into account the drawbacks of this type of antennas so that their use is not limited. Recently, LWAs have been proposed for low-cost localization applications, as they allow the design of planar structures with directive beams. In addition, due to the exponential increase in the use of technology, it is necessary to find new technologies for higher, faster and more efficient data transmission while maintaining low manufacturing costs. Therefore, LWAs can be a crucial solution mixing low manufacturing costs, high integrability in different systems due to their planar printed technology and high directivity while taking advantage of their dispersive characteristic that provides passive frequency scanning. In this context, the main contribution of this Thesis consist of the study, analysis, design and integration of LWAs in real and practical applications. This Thesis presents the following three main contributions, defined in the three main blocks of this document: • Study and analysis of LWAs for its use in direction of arrival estimation systems based on monopulse amplitude techniques. Compare the characteristics and performance of LWAs along with widely used commercial antennas. For this purpose, design and manufacture the HWM-LWAs in order to compare their performance with commercially acquired panel antennas. Since each application requires the design of a new and different HWM-LWA, a main objective of this block is to study and propose an efficient antenna analysis and design technique to facilitate obtaining frequency-scanned monopulse patterns. • Once analyzed that LWAs are a feasible solution for its use in real localization applications due to their several advantages, integrate the designed half-width microstrip (HWM-LWAs) in digital indoor angle-of-arrival estimation systems. Therefore, design, develop, configure and integrate LWAs in different systems based on the Wi-Fi ISM 2.4 GHz and 5 GHz frequency bands. Finally, compare the obtained estimation results with other proposed solutions to corroborate that LWAs can be used in real applications. • Extending the use of antennas for angular localization in sensor networks using the 900 MHz UHF frequency band: the main properties of low manufacturing cost and passive frequency beam scanning can be used in other applications. Thus, the localization estimation of passive RFID tags is studied, as well as their application in Wireless Sensor Networks (WSNs) using active tags with LORA technology. This document is presented as a Thesis by compilation, so the 4 journal articles that have been published during the Ph.D program will be presented and briefly explained. Besides, some conference articles and other work under review will be also presented to expose some of the research that has not been published in journals. The document is organized as outlined hereafter: In Part I, a state-of-the-art contextualization, a rigorous explanation about LWAs and the previous applications mentioned above is presented. The next two parts are dedicated to present and briefly explain the published works included in this Thesis and their main contributions. In Part II the explanation of the four papers which compose the compendium are presented. This is, LWAs analysis for direction of arrival estimation and the integration of LWAs in digital Wi-Fi localization systems in chapter 1, the UHF 900 MHz ISM frequency band is used in conjunction with HWM-LWAs in chapter 2, then, it is implemented in a real time system for direction of arrival estimation of multi RFID tags in chapter 3 and LoRa integration in chapter 4. Finally, in Part III, the overall conclusions and the future research lines are discussed.Esta tesis doctoral se presenta bajo la modalidad de compendio de publicaciones. Está formada por un total de cuatro artículos. Article 1.-: A. Gil-Martinez, M. Poveda-Garcia, J. A. Lopez-Pastor, J. C. Sanchez-Aarnoutse and J. L. Gomez-Tornero, Wi-Fi Direction Finding with Frequency-Scanned Antenna and Channel Hopping Scheme IEEE sensors Journal, , vol. 22, no. 6, pp. 5210-5222, 2022. DOI: 10.1109/JSEN.2021.3122232. Article 2.-: A. Gil-Martinez, M. Poveda-Garcia, D. Cañete-Rebenaque, and J. L. Gomez-Tornero, Frequency-Scanned Monopulse Antenna for RSSI-based Direction Finding of UHF RFID tags IEEE Antennas and Wireless Propagation Letters,, vol. 21, no. 1, pp. 158-162, 2022. DOI: 10.1109/LAWP.2021.3122232. Article 3.-: A. Gil-Martinez, M. Poveda-Garcia, J. Garcia-Fernandez, M. Campo-Valera, D. Cañete-Rebenaque, and J. L. Gomez-Tornero, Direction Finding of RFID tags in UHF Band Using a Passive Beam-Scanning Leaky-Wave Antenna IEEE Journal of Radio Frequency Identi cation, doi: 10.1109/JRFID.2021.3122233. Article 4.-: J. L. Gomez-Tornero, A. Gil-Martinez, M. Poveda-Garcia and D. Cañete-Rebenaque, ARIEL: Passive Beam-Scanning Antenna TeRminal for Iridiscent and E cient LEO Satellite Connectivity in IEEE Antennas and Wireless Propagation Letters, doi: 10.1109/LAWP.2022.3193040.Escuela Internacional de Doctorado de la Universidad Politécnica de CartagenaUniversidad Politécnica de CartagenaPrograma Doctorado en Tecnologías de la Información y las Comunicacione

Track-Initiated Beam Spoiling for Improved Tracking with Digital Phased-Array Radars

Radar systems have become highly dynamic with the advancements in all-digital radar architectures. All-digital radar architectures introduce the potential for dynamic beamforming. This thesis will detail the fundamentals that are the foundation of radar signal processing (RSP) and modeling a digital phased array radar. This thesis will detail the techniques used for digital beamspoiling. The intentional beamspoiling is intended to improve the trackers’ ability to track a target continuously. When a high-speed target falls out of a beam due to a maneuver, the radar will spoil the transmit beam illuminating a wider scene. The wider illuminated scene allows for a higher likelihood of accurately detecting the target, allowing the tracker to track the target continuously. This thesis will discuss the theory and application of the trackers used in the simulation. With the beamspoiling and trackers, this thesis will analyze the ability of an all-digital phased array to track a target utilizing dynamic beamforming to improve the tracking performance. Finally, it will detail the improvement of the trackers’ ability to track when utilizing beamspoiling for specific situations, allowing the radar to track targets for a more extended time. The results varied based on the amount a transmit beam was spoiled due to the loss in SNR that naturally occurs from the decrease in power density

Dual-Channel Particle Filter Based Track-Before-Detect for Monopulse Radar

A particle filter based track-before-detect (PF-TBD) algorithm is proposed for the monopulse high pulse repetition frequency (PRF) pulse Doppler radar. The actual measurement model is adopted, in which the range is highly ambiguous and the sum and difference channels exist in parallel. A quantization method is used to approximate the point spread function to reduce the computation load. The detection decisions of the PF-TBD are fed to a binary integrator to further improve the detection performance. Simulation results show that the proposed algorithm can detect and track the low SNR target efficiently. The detection performance is improved significantly for both the single frame and the multiframe detection compared with the classical detector. A performance comparison with the PF-TBD using sum channel only is also supplied

Dynamic Multipath Model of Low Angle Passive Radar Tracking with Experimental Evaluation

The problem of multipath propagation encountered in radar tracking of low elevation targets in the presence of reflections from the sea is addressed. A detailed model of the multipath  propagation considering both the specular and the diffuse reflection components in target tracking using passive radars is established. Based on the geometry of the specular and the diffuse reflections, expressions for the reflection coefficient and the scattering field are derived. Experiments in the outfield indicate that the model proposed agrees with the test data well, which can provide an accurate prediction of the angle measurement errors in the presence of multipath effects.Defence Science Journal, 2012, 62(5), pp.331-337, DOI:http://dx.doi.org/10.14429/dsj.62.100

Nuevos sistemas de Localización INDoor de dispositivos IoT (LINDIOT)

[SPA] Esta tesis doctoral se presenta bajo la modalidad de compendio de publicaciones. Los sistemas de localización de los dispositivos que forman el Internet de las Cosas (loT) se basan, habitualmente, en sistemas satelitales (GNSS). Sin embargo, debido a la dificultad que tienen las ondas electromagnéticas de atravesar las paredes y techos de los edificios, los sistemas satelitales no ofrecen una precisión adecuada en interiores de edificios. Por lo tanto, no pueden ser empleados en aplicaciones como localización, navegación o guiado de personas en estos entornos. Al no poder emplearse los sistemas de localización satelitales, se han desarrollado diversas propuestas, algunas propietarias y otras de ámbito científico, que permiten la localización de dispositivos loT en entornos indoor. Estas propuestas emplean tecnologías tan diversas como imagen, radiofrecuencia, sensores inerciales, sensores de campo magnético, e incluso señales acústicas. En esta tesis nos centraremos en los sistemas basados en radiofrecuencia, dado que se trata de los más ampliamente utilizados. Dentro de los sistemas basados en radiofrecuencia, dependiendo de la infraestructura empleada y del propósito del mismo, se pueden emplear diferentes tecnologías para su funcionamiento, entre ellas destacan: WiFi, Zigbee, UWB o Blueetooth Low Energy. La tecnología WiFi ha sido una de las predominantes a la hora de implementar los sistemas de localización en interiores, sobre todo en grandes edificios con gran número de visitantes como son aeropuertos, centros comerciales, museos, etc. Esto se debe a que en este tipo de instalaciones suele existir una amplia red WiFi desplegada para dotar de conectividad a los visitantes. Esta red puede ser empleada a su vez para la generación de sistemas de localización, ahorrando así el despliegue de nueva infraestructura. Se ha de tener cuenta que el coste del despliegue de infraestructura, incluyendo equipos, cableado, ingeniería, etc., suele ser una de las tareas más costosas dentro de cualquier proyecto de ingeniería. Es por ello que se tiende a reutilizar las redes WiFi-existentes dotándolas de otras funcionalidades, además de la propia de conectividad. Una de las principales clasificaciones de los sistemas de localización suele dividir a los mismos entre sistemas activos y pasivos. Los sistemas activos requieren la intervención del dispositivo a localizar mediante una aplicación y/o proceso que recoge información del espectro RF a su alcance, mientras que los sistemas pasivos recogen la señal RF de los dispositivos loT que detectan, pero no requieren de su participación. Durante el desarrollo de esta tesis se ha trabajado en los dos tipos de sistemas, estando dividida la investigación en dos partes claramente diferenciadas. En la primera parte de la tesis se ha trabajado en los sistemas de localización pasivos, concretamente en sistemas de localización mediante la técnica conocida como radar monopulso empleando el estándar WiFi 802.11. Posteriormente se trabajó en la técnica radar monopulso en campo cercano y, a continuación, se combinó con sistemas de ranging basados en el estándar 802.llmc. Mediante la combinación de ambas tecnologías se generó un sistema de localización empleando un único punto de acceso (AP). Por último, el trabajo final de este bloque empleó antenas de haz con escaneo en frecuencia, técnicas de channel-hopping y el algoritmo MUSIC para ampliar el FoV de los dispositivos pasivos implementados en el trabajo anteriore. En la segunda parte de la tesis se ha trabajado en la implementación de un IPS (lndoor Positioning System) de smartphones para grandes superficies, empleando únicamente los APs que ya se encuentran instalados y con una precisión zonal a nivel tienda/pasillo. El IPS es una de las piezas fundamentales de un mecanismo mayor conocido como Sistema de Marketing Contextual. Junto con la descripción detallada del IPS, se explican todos los componentes e intercambios de información entre los diferentes bloques que forman el Sistema de Marketing Contextual. [ENG] This doctoral dissertation has been presented in the form of thesis by publication. the location and positioning systems involved in the Internet of the Things (IoT) paradigm are generally based on satellite systems (GNSS). However, because the electromagnetic waves have difficulties getting through the walls and roof of the buildings, the satellite systems do not have enough accuracy indoors. Therefore, this kind of system cannot be employed in the location and navigation of IoT devices or people indoor. Because satellite tracking systems cannot be employed, several proposals are focused on overcoming the indoor location of IoT devices. Some proposals are from the scientific area, and some other proposals are proprietary. These proposals employ different technologies like image-based, radiofrequency, inertial sensors, magnetic field sensors, and acoustic signals. This Ph.D. thesis will focus on radio frequency-based systems because they are the most frequently used. Among the radio frequency-based systems, several technologies can be employed according to the infrastructure employed and the purpose of the project. These technologies are WiFi, Zigbee, UWB, or Bluetooth Low Energy. WiFi technology has been one of the most employed in indoor location systems, particularly in large infrastructures with a high number of visitors such as airports, malls, museums, etc. This is mainly because there is often a wide WiFi network already deployed to provide connectivity to visitors in this kind of infrastructure. This network could also be employed to implement the location system, saving savings in deploying the system. It should be taken into consideration that the main cost of any project is the infrastructure deployment phase, where the wiring and the new equipment acquisition are carried out. Because of the aforementioned cots, the WiFi networks are often reused with other applications than the data connectivity. One of the main classifications of the indoor location system usually divides them into active and passive. The active systems require the participation of the device to be located by using an app that collects the data from the RF within the range. However, the passive systems collect the RF signal of the IoT devices within the range but do not require their involvement. In this thesis, we have worked on the two kinds of systems. In the first chapters, we have worked in the passive location systems, mainly in the WiFi RADAR monopulse function-based systems based on the 802.11 standard. Next, we focused on the near-field monopulse technique, and later we merged this technique with a ranging system based on the 802.11mc standard. The last work of this section employed a frequency beam antenna with channelhopping techniques and the MUSIC algorithm to increase the FoV of the previously implemented devices. In the following chapters, we work on implementing a smartphone Indoor Positioning System (IPS) for large infrastructures. One of the main premises of our IPS is the use of the already deployed APs with zonal accuracy. The IPS is one of the key enabling technologies of a Marketing Contextual System. Moreover, the component and information flows between the different blocks that make up the Contextual Marketing System are explained.[ENG] This doctoral dissertation has been presented in the form of thesis by publication. The location and positioning systems involved in the Internet of the Things (IoT) paradigm are generally based on satellite systems (GNSS). However, because the electromagnetic waves have difficulties getting through the walls and roof of the buildings, the satellite systems do not have enough accuracy indoors. Therefore, this kind of system cannot be employed in the location and navigation of IoT devices or people indoor. Because satellite tracking systems cannot be employed, several proposals are focused on overcoming the indoor location of IoT devices. Some proposals are from the scientific area, and some other proposals are proprietary. These proposals employ different technologies like image-based, radiofrequency, inertial sensors, magnetic field sensors, and acoustic signals. This Ph.D. thesis will focus on radio frequency-based systems because they are the most frequently used. Among the radio frequency-based systems, several technologies can be employed according to the infrastructure employed and the purpose of the project. These technologies are WiFi, Zigbee, UWB, or Bluetooth Low Energy. WiFi technology has been one of the most employed in indoor location systems, particularly in large infrastructures with a high number of visitors such as airports, malls, museums, etc. This is mainly because there is often a wide WiFi network already deployed to provide connectivity to visitors in this kind of infrastructure. This network could also be employed to implement the location system, saving savings in deploying the system. It should be taken into consideration that the main cost of any project is the infrastructure deployment phase, where the wiring and the new equipment acquisition are carried out. Because of the aforementioned cots, the WiFi networks are often reused with other applications than the data connectivity. One of the main classifications of the indoor location system usually divides them into active and passive. The active systems require the participation of the device to be located by using an app that collects the data from the RF within the range. However, the passive systems collect the RF signal of the IoT devices within the range but do not require their involvement. In this thesis, we have worked on the two kinds of systems. In the first chapters, we have worked in the passive location systems, mainly in the WiFi RADAR monopulse function-based systems based on the 802.11 standard. Next, we focused on the near-field monopulse technique, and later we merged this technique with a ranging system based on the 802.11mc standard. The last work of this section employed a frequency beam antenna with channelhopping techniques and the MUSIC algorithm to increase the FoV of the previously implemented devices. In the following chapters, we work on implementing a smartphone Indoor Positioning System (IPS) for large infrastructures. One of the main premises of our IPS is the use of the already deployed APs with zonal accuracy. The IPS is one of the key enabling technologies of a Marketing Contextual System. Moreover, the component and information flows between the different blocks that make up the Contextual Marketing System are explained.Esta tesis doctoral se presenta bajo la modalidad de compendio de publicaciones. Está formada por estos seis artículos: 1. J. L. Gómez-Tornero, D. Cañete-Rebenaque, J. A. López-Pastor and A. S. Martínez-Sala, "Hybrid Analog-Digital Processing System for Amplitude-Monopulse RSSI-Based MiMo WiFi Direction-of-Arrival Estimation," in IEEE Journal of Selected Topics in Signal Processing, vol. 12, no. 3, pp. 529-540, June 2018, doi: 10.1109/JSTSP.2018.2827701. 2. J. A. López-Pastor, A. Gómez-Alcaraz, D. Cañete-Rebenaque, A. S. Martinez-Sala and J. L. Gómez-Tornero, "Near-Field Monopulse DoA Estimation for Angle-Sensitive Proximity WiFi Readers," in IEEE Access, vol. 7, pp. 88450-88460, 2019, doi: 10.1109/ACCESS.2019.2925739. 3. J. A. López-Pastor, P. Arques-Lara, J. J. Franco-Peñaranda, A. J. García-Sánchez and J. L. Gómez-Tornero, "Wi-Fi RTT-Based Active Monopulse RADAR for Single Access Point Localization," in IEEE Access, vol. 9, pp. 34755-34766, 2021, doi: 10.1109/ACCESS.2021.3062085. 4. J. A. López-Pastor, A. J. Ruiz-Ruiz, A. J. García-Sánchez, and J. L. Gómez-Tornero, “An automatized contextual marketing system based on a wi-fi indoor positioning system,” Sensors, vol. 21, no. 10, pp. 1–26, 2021 5. J. A. Lopez-Pastor, A. J. Ruiz-Ruiz, A. S. Martinez-Sala, and J. Luis Gomez-Tornero, “Evaluation of an indoor positioning system for added-value services in a mall,” in 2019 International Conference on Indoor Positioning and Indoor Navigation (IPIN), 2019, pp. 1–8 6. A. Gil-martínez, M. Poveda-garcía, J. A. López-pastor, J. C. Sánchez-aarnoutse, and J. L. Gómez-tornero, “Wi-Fi Direction Finding with Frequency-Scanned Antenna and Channel-Hopping Scheme,” IEEE Sens. J., vol. XX, no. Xx, pp. 1–9, 2021.Escuela Internacional de Doctorado de la Universidad Politécnica de CartagenaUniversidad Politécnica de CartagenaPrograma de Doctorado en Tecnologías de la Información y las Comunicacione

Antenna array design for retrodirective wireless power transmission and radar

This thesis presents antenna array design and the integration of microwave circuit systems for retrodirective wireless power transmission and radar. Wireless power transmission (WPT) and automotive radar are emerging topics which have attracted a lot of interest in the past few years. The development of these systems usually brings high associated costs if competitive performance is required. The first part of the thesis is concerned with the development of a new retrodirective antenna array (RDA) system for WPT which uses sub-arrays in transmit to save costs, however, losing tracking in one plane. Nevertheless, depending on the application, the proposed system might be an alternative solution to existing approaches as similar performances are achieved, but at generally a lower cost for the proposed RDA design as compared to the conventional solution. The proposed system has been designed to work in the ISM band (2.5 GHz for receiving and 2.4 GHz for transmitting) which exhibits an 80◦ 3-dB half-power beamwidth for the monostatic pattern. Additionally, it has been demonstrated that the system is able to work in the near-field region, being able to achieve wireless charging of a handeld electronic device at a 50 cm distance. The power for the beacon signal sent by the device to be charged by the system (for tracking purposes) is 6.6 dBm, whereas the received RF power from the RDA is in excess of 27 dBm, which means that the device is receiving a hundred times the power sent for battery charging. On the other hand, the second part of the thesis relates to the development of two important elements within a frequency-modulated-continuous-wave (FMCW) auto motive radar working at 24 GHz: a substrate integrated waveguide (SIW) butler matrix antenna array as the transmitter and a new post-processing technique called Pwr+. These two in combination bring some interesting advantages in terms of angular resolution improvements when compared to conventional single-input-multiple output (SIMO) radars. For example, the proposed system is able to distinguish two targets which are 2 degrees apart as well as a higher field-of-view (FOV) thanks to the beamforming network that generates 4 individual beams covering a wide FOV. The newly developed radar system is also comparable to multiple-input-multiple output (MIMO) radars but with the added value of having a shorter processing time, which for automotive radar applications is a crucial characteristic to be minimized, and could, therefore, avoid potential road accidents. It should also be mentioned that this thesis was supported by the Samsung Advanced Institute of Technology