Programa del congreso

This paper demonstrates for the first time a dual polarization reconfigurable reflectarray antenna based on Liquid Crystal (LC) that operates at W-band. The antenna is electrically large and is capable of independently steering the beam of two orthogonal polarizations. Two different implementations of single-layer unit cells (single resonant and multi-resonant) capable of providing suitable phase range to independently control the two RF polarizations with enough isolation have been investigated. The single resonant cell was finally used to design a complete reflectarray antenna made of 55X55 elements, for which an accurate and efficient modeling of the cells was implemented. The antenna shows 35º of 1D scanning range with 25dBi gain and a maximum SLL of -9dB in the entire range for both polarizations at 98 GHz.

This paper presents an electrically large multi-faceted aperture that can be folded and deployed onboard an aerospace vehicle. Following a single-offset configuration, the aperture comprises five low-profile panels assembled edge-to-edge, arranged following a parabolic curvature. The entire antenna structure is designed to generate a directive beam in Ka-band, working in dual-linear polarization. An electromagnetic characterization of this topology has been carried out, compared the results to the performance of an equivalent single facet reflector and a multi-faceted reflectarray composed of nine panels. The five panel multi-faceted structure features a directive pattern stable in-band, and a 1dB-gain bandwidth of 10%, significantly higher than in an equivalent single facet aperture. Compared with the nine-panel structure, it exhibits lower gain bandwidth but higher peak gain, similar beamwidth in-band and easier integrability with the vehicle platform.

En el contexto de transmitarrays de doble banda, el diseño de celdas unitarias presenta grandes desafíos debido a la necesidad de cumplir con especificaciones de fase simultáneas e interrelacionadas en ambas bandas de frecuencia, esenciales para funcionalidades como el direccionamiento de haz a través del desplazamiento mecánico de la alimentación. Este estudio introduce un enfoque efectivo para el diseño de celdas unitarias, aprovechando una implementación personalizada del método de los momentos en el dominio espectral (SD-MoM, por sus siglas en inglés). Este método permite calcular la respuesta de onda completa de las celdas unitarias a un coste computacional significativamente menor en comparación con el software comercial de propósito general (de dos a cuatro órdenes de magnitud). La metodología emplea una estrategia novedosa que implica un algoritmo genético para ayudar en la búsqueda de soluciones óptimas de celdas unitarias. Esta estrategia es factible debido a la eficiencia y precisión del SD-MoM en la evaluación de cada función de fortaleza. Como demostración práctica, se diseña un conjunto de celdas unitarias para operar en comunicaciones satelitales de banda Ka, específicamente en las bandas de frecuencias de 19.7-20,2 GHz y 29.5-30 GHz. Las celdas unitarias resultantes muestran un grosor sustancialmente reducido en comparación con diseños anteriores destinados a las mismas bandas de frecuencia.

This paper presents a guide to design unit cells for reflectarrays and transmitarrays based on unit cells with 3-D geometry. To explain the design process, a metal-only unit cell with basic 3-D geometry in a periodic environment is considered. The parts to be considered in the 3-D unit cell structure as well as their importance in the electromagnetic behavior in reflection are described. The inclusion of an impedance transformer at the interface between the 3-D unit cell and the free space is analyzed. Based on the design of the 3-D unit cell in reflection (for reflectarray design), its modification for transmitarray design is introduced. Finally, design strategies to modify the phase in transmission in 3-D unit cells are described and one of them based on meandered lines is assessed and discussed.

El sistema expuesto en este trabajo propone un cambio de paradigma en la tecnología utilizada comercialmente en la implementación de sistemas de seguridad inalámbricos. La principal diferencia radica en el uso de técnicas de retrodispersión juntamente con señales de espectro ensanchado. Este cambio de tecnología permite reducir por debajo del miliamperio el consumo de los nodos inalámbricos, lo que permite prescindir de las baterías, y consecuentemente, eliminar el mantenimiento periódico necesario de los sistemas comerciales. Esta comunicación aborda los diferentes retos y soluciones para la implementación del sistema (protocolo de comunicación, implementación del hardware, etc.), centrándose principalmente en el diseño del sensor inalámbrico.

The fusion of Augmented, Mixed and Virtual reality known as Extended Reality (XR) is revolutionizing how we interact with digital environments. This paper explores the concept of dark patterns and their implications in the design of XR applications. We examine how such patterns impact user experience, raise ethical concerns, and are relevant in the near-future Metaverse applications. In addition, we introduce a classification system consisting of five types of dark patterns, underscoring the importance of educating users and enforcing ethical guidelines to protect privacy and data in XR scenarios. The described approach provides a comprehensive understanding of the practical hurdles posed by dark patterns in this domain, encompassing issues like user well-being, ethical design in Extended Reality, and the influence of dark patterns on user perceptions and behaviors within the rapidly advancing technological landscape.

El artículo presenta la implementación de una red de prueba Wi-Fi con múltiples puntos de acceso, facilitando la evaluación de diversos algoritmos de selección de canal. Compuesto por múltiples puntos de acceso, un controlador central y un conjunto de dispositivos clientes, la arquitectura de la red refleja un escenario realista similar a un ISP que gestiona varios puntos de acceso en áreas urbanas densamente pobladas. Aprovechando los protocolos MQTT y HTTP para la comunicación, junto con Docker para implementación de software simplificada, la red permite la evaluación de algoritmos de selección de canal, ya sea basados en aprendizaje automático o reglas heurísticas.

This paper presents the development and evaluation of a novel indoor localization device that integrates Ultra-Wideband (UWB), WiFi, and WiFi Fine Timing Measurement (FTM) technologies. By combining these technologies, our work aims to enhance localization accuracy and reliability compared to systems reliant on a single technology. A hardware prototype is developed, and the necessary infrastructure for its operation is described, along with a specialized localization algorithm that adapts to the characteristics of the combined signals. Measurement results from a test environment demonstrate significant improvements in precision and reliability. This integrated approach also contributes to cost reduction by opportunistically utilizing existing reference points within a scenario.

Empty substrate integrated waveguide (ESIW) is a transmission line that appeared to improve the well-known substrate integrated waveguide (SIW). This improvement consists of removing the dielectric substrate that does not allow the SIW performance to be good at high frequency. As it is a relatively new technology, not all the devices that have been presented based on SIW technology have been designed in ESIW. One of the devices that has not been designed yet in ESIW is a circulator. Thus, a ferrite-based Y-junction circulator designed and fabricated in ESIW technology to operate at a central frequency of 30 GHz is presented. The results obtained by the full wave simulations and the experimental measurements exhibit the correct operation of the circulator at Ka band.

In this work, we present a new compact topology of interdigital bandpass filters implemented in coaxial waveguide technology. Compared to classical coaxial resonators, which are typically loaded with cylindrical metallic posts, the resonators that we propose are based on rectangular cavities loaded with flat metallic strips of a finite thickness. The main advantages of the proposed topology are compactness and

low-cost practical realization. The design process, which is based on the calculation of the input/output and the inter-resonator couplings, employs the well-known Aggressive Space Mapping technique, with the aim of reducing the overall computation effort. In order to validate the new proposed topology and the design procedure, interdigital filters of orders 3 and 5 operating in the S-band have been designed. For validation purposes, the obtained results have been successfully compared to data provided by two different full-wave software tools (Ansys HFSS and CST Studio Suite).

Este artículo muestra la solución adoptada para suprimir una interferencia generada por un potente radar de basura espacial a 1,75 Km de la estación RAEGE Santa María.Dada la alta sensibilidad requerida en los receptores radioastronómicos, los filtros superconductores de alta temperatura (HTS) son la mejor solución a adoptar para degradar en la menor medida de lo posible los receptores ultra sensibles utilizados. Por ello, un filtro HTS basado en resonadores espirales ha sido diseñado, fabricado e instalado en la estación.

El rechazo de este filtro ha permitido al radiotelescopio RAEGE Santa María observar en presencia de este radar.

This paper presents the practical implementation of a diplexer, for satellite applications designed using Empty Substrate Integrated Waveguide (ESIW) technology. The proposed diplexer comprises two bandpass ESIW filters based on inductive windows and a resonant T-junction. The filters are centered at 11.575 GHz and 11.825 GHz, both with bandwidths of 155 MHz. The proposed diplexer demonstrates return and insertion losses better than 23 dB and lower than 0.30 dB, respectively, as well as an isolation level better than 30 dB. This technology enables the creation of a high-performance diplexer with a focus on Size, Weight, Power, and Cost (SWaP-C) as crucial indexes.

This work presents an in-vehicle monitoring system based on a PCR (Pulsed Coherent Radar) at the 60 GHz ISM unlicensed band. Since the radar can measure distances and displacements with sub-millimeter resolution, a system for seat occupancy detection and vehicle occupants’ gesture recognition and breathing monitoring is proposed. The measured results of breathing agree with those obtained by another system whose measurements are based on the airflow, which allows for its validation.

According to the OMS, the highest rate of death among non-communicable diseases is caused by cardiovascular disorders (CVDs), killing approximately 18 million people yearly. Early detection of arrhythmias or CVDs is critical. For this reason, new portable acquisition devices have made it possible the recording of electrocardiograms (ECGs) for extended periods of time. This is the most common method for identifying arrhythmias with a random nature. However, the acquisition environment may cause distortions or even destroy the ECG recordings, making difficult to diagnose CVDs accurately. As a result, the evaluation of the ECG signal quality is required. The suggested method is based on feature and meta-feature extraction capabilities from 5-second ECG segments, allowing machine learning classifiers to identify between ECG segments of high and low-quality. Results showed that the utilization of meta-features increases the accuracy of the methodology, compared with the utilization of the original hand-crafted feature set.

This article presents a broadband rectangular-shaped patch antenna with coplanar feed. The antenna is composed of a ground plane and a step-shaped radiating patch. The final size of the proposed antenna is 30 x 30 mm², and it is manufactured onto a low-cost FR4 substrate. The measured results of the antenna indicate that its operating range is between 2.5 and 24.9 GHz, the gain is between 2.1 and 5.4 dBi, and it presents omnidirectional radiation patterns. The results of the antenna in the time domain are also evaluated, with a very high similarity between transmitted and received broadband pulses and high integrity of the transmitted signals. After the evaluation of the results obtained with the proposed antenna, it is shown that it is a good candidate to be used in a medical imaging system.

Cardiovascular data provides valuable information into daily health, and the increasing adoption of wearable devices, such as photoplethysmography (PPG), promises extensive diagnosis and analysis capabilities. However, validation through established clinical standards like electrocardiogram (ECG), either simultaneously or closely aligned with PPG, remains essential for validating cardiac disease diagnosis. This paper introduces a novel approach to synchronize ECG and PPG recordings based on the cardiac variability dynamics and non-linear techniques. Through a ``proof of concept" analysis on a controlled dataset of 13 patients, the efficacy of mutual information (MI) versus linear correlation (LC) is compared. The findings underscore the superior performance of MI over the traditional LC method, thereby highlighting immediate opportunities for further research on signal synchronization, particularly in scenarios involving the physical collection of cardiovascular data from different devices.

This keynote speech explores the significance of Galileo, Europe’s Global Navigation Satellite System (GNSS) in shaping modern society. Using a constellation of 24 satellites in Medium Earth Orbit (MEO), Galileo delivers unparalleled worldwide position, navigation and timing services using state-of-the-art technology. We will focus on how GNSS systems work, including the fundamental technological aspects and scientific principles underpinning these systems. Furthermore, we will present both existing and upcoming Galileo services and applications that hold tremendous benefits for European society.

In this context, the European Commission’s Joint Research Center (JRC) has an instrumental role in supporting the evolution of European satellite navigation programs. As the European Union’s GNSS Test and Demonstration Hub, JRC fosters the development of Galileo applications, provides technical support to European industry and policymakers, and shapes the evolution of Galileo’s Second Generation. We will showcase some of the unique research facilities at JRC, and their significance in advancing satellite navigation and driving innovation for a more efficient and prosperous society.

This article presents the theoretical study and numerical simulation for the implementation of a stub resonator in the microstrip ridge gap waveguide (MGCW) transmission line. The resonator is filled with liquid crystal (LC) and, thanks to LC’s dielectric anisotropy properties, the resonance can be easily controlled using an external electric or magnetic bias field. The resonance was designed to operate in the range of 7.8 to 8.8 GHz. Its frequency response, associated to both parallel and perpendicular LC’s permittivity, as well as intermediate state were computed. Finally, the results are discussed.

In this paper, we describe the design of a periodically air-filled substrate integrated waveguide (SIW) bandpass filter in which part of the dielectric substrate is removed to reduce insertion losses. The unit cell parameters of the structure, which are directly related to the center frequency (fc) and bandwidth (BW) of the first passband, and also to the first stopband or bandgap (BG) of the structure, have been appropriately selected for filtering purposes, thus providing some useful design rules. Furthermore, we apply the concept of glide symmetry for achieving a much larger fractional bandwidth (FBW). Additionally, a microstrip-to-SIW transition including a novel coupling iris is proposed. A prototype of the periodic SIW filter with glide symmetry has been manufactured and measured for validating purposes. The proposed filter proves to be a good candidate for millimeter wave applications.

This paper introduces a theoretical framework for deriving fully analytical and multi-modal equivalent circuits for periodic structures and metasurfaces in general. By introducing time as a new variable, classical versions of circuits for purely spatial scenarios are expanded to account for spacetime-varying ones. Throughout the document, various periodic structures are examined from a circuit perspective, exhibiting periodicity in space, time, and spacetime. The efficiency of the analytical circuits is confirmed through external full-wave solvers, affirming the models as valuable tools for investigating innovative and advanced spacetime scenarios.

A design methodology to realize Fabry-Pérot cavity antennas with very high aperture efficiency and improved bandwidth is presented. The antenna is based on a tapered Partially Reflective Surface, and its characteristics are determined through a combination of criteria from the simplified ray-model and the 2D leaky-wave approaches. Therefore, through a transmission line modelling of the PRS, its cells can be chosen to follow the required leakage factor function while satisfying the resonance condition and the positive phase-slope technique. Two different designs are carried out to present a quasi-uniform aperture field distribution. Their simulated behaviours are compared with the best design of a previous work, clearly showing the improvement achieved from incorporating the leaky-wave theory into these antennas.

In the last weeks, a major attack on the supply chain of a large base of Free Software was uncovered. The attack was carefully executed on the time frame of several years, where technical expertise and psychological operations were deployed by a malicious party with the objective of opening a backdoor in Linux-based systems. The backdoor was, allegedly, targeted towrds SSH, one of the most important services running over the Internet, and was executed by including malicious code in one of the dependencies, the XZ utils compression library. This paper will describe the attack, what would be its consequences, especially in the telecommunications sector, and what cautions can be taken to prevent future similar attacks.

Time-Sensitive Networking (TSN) en aviónica es un área en desarrollo que busca aprovechar las capacidades delos estándares TSN para mejorar la comunicación en tiempo real y la interoperabilidad en sistemas aeroespaciales. Por lo tanto, esta investigación describe la implementación de un banco de pruebas destinado a validar redes TSN, asegurando que cumplan con los estrictos requisitos de sincronización y latencia de las aplicaciones de aviónica. Al proporcionar una plataforma integral para pruebas y validación, el banco de pruebas contribuirá al avance de la tecnología TSN en aplicaciones aeroespaciales, mejorando en última instancia la seguridad y eficiencia de las operaciones aéreas.

This paper presents the development of a bidirectional communication interface between two devices whose sole link is through the use of QR Codes. In this way, the original QR functionality is extended with a file transfer service, while a new secure link, save from radiofrequency interference and eavesdropping, is provided for an easy and secure personal device synchronization. The implemented communication system has been designed to connect devices equipped with screens and cameras. Two versions have been developed. One, as a proof of concept, on two Raspberry Pi units, and the other, focused on the end user, on Android smartphones, that can be download and installed from the official Store site.

El progreso en las tecnologías inalámbricas y la creciente demanda de la sociedad de mantenerse permanentemente conectada han elevado la importancia de las comunicaciones inalámbricas hasta convertirlas en un aspecto esencial de la vida cotidiana. Además, el mayor impacto en el crecimiento del tráfico de red se atribuye a la aparición de servicios de video streaming. Por lo tanto, el objetivo de este trabajo es investigar el impacto que tienen las condiciones de una red Wi-Fi en la calidad de experiencia (Quality of Experience, QoE) de video streaming del usuario. Para ello, este artículo presenta un sistema basado en modelos de clasificación y regresión de aprendizaje automático (Machine Learning, ML) para la estimación de Key Quality Indicators (KQIs) basados en las métricas y los parámetros de configuración a bajo nivel de la red Wi-Fi.

We introduce a novel reflectarray unit cell based on a SIW cavity resonator, designed for operation at 18.7 GHz. It can achieve a full phase cycle of phase shifting and low losses, while keeping manufacturing requirements simple. Furthermore, by relying on a resonant cavity instead of open elements, inter-cell coupling effects are reduced. This can lower the approximation errors resulting from using the cell response under a fully periodic environment during the design process.

This contribution describes a dual-band polarizing reflectarray antenna for small-satellite communications. The proposed an-tenna has been designed to convert the incident dual-linearly polarized field into dual-circular polarization in K and Ka bands, generating a high gain beam as well. The unit-cell is composed of two layers of metallization, where each layer has orthogonal groups of dipoles and is designed to independently operate at a different frequency. The polarization conversion process has been generalized to operate with non-stacked dual polarization elements, which allows to use a single dielectric layer per operating frequency. Simulated results of a 20 cm polarizing reflectarray antenna with a dual-layer configuration show a maximum gain larger than 30 dBi and an axial ratio below 1.5 dB at both design frequencies (19.7 and 29.5 GHz).

In this contribution, two designs of dual-band reflectarray surfaces are proposed for coverage-enhancing applications in millimeter-wave 5G networks. The first design is based on a two-layer reflectarray panel with simultaneous operation at 28 and 39 GHz, which is able to generate two independent collimated beams in dual polarization (one beam at each frequency). The second design is based on a single-layer reflectarray that operates at 28 and 60 GHz. In this case, a beamforming technique has been applied to broaden the beams in the azimuth plane, in order to cover a wider angular range. The proposed reflectarrays can be used to enable wireless communications in millimeter-wave networks, providing coverage of blind zones in both indoor and outdoor scenarios.

Cost-effective multibeam millimeter wave antenna solutions are required to enable the deployment of 5G NR . The complex trade-off between system complexity and RF requirements (such as high gain, number of beams, beam scanning capability, ) needs to be carefully optimzed. Transmit-arrays (TAs) can provide a low-cost solution for multibeam operation by having aN feeding array placed at a given focal distance. However, the maximum number of feeds and cross-over levels are constrained by the focal distance to aperture diameter ratio (F/D). On the one hand, reducing the F/D allows designing more compact feeding array elements, on the other hand, it limits the maximum angle coverage due to scanning aberrations. In this work, we show that a TA optimized for operating simultaneously with low F/D and wide-angle coverage can improve the performance of this classical configuration. We design a Ka-band multibeam antenna with a TA fed by a 19x5 array of standard WR38 waveguide operating with F/D=0.34. It provides 25 dBi of gain with scan losses below 3 dB when scanning in a zenith plane up to -55 degrees, covering 80 degrees (-55 to 25 degrees) with cross-over levels around 3 dB.

Este trabajo se presenta en el contexto del estudio, desde una perspectiva bioeléctrica, de las enfermedades neurodegenerativas relacionadas con los efectos de la demielinización sobre la transmisión de impulsos nerviosos. Mediante una sencilla ecuación de línea de transmisión unidimensional para modelar la membrana pasiva, acoplada con la bomba de regeneración activa de los nódulos de Ranvier, se calcula el umbral de densidad de corriente de despolarización, junto con los niveles de atenuación y velocidad de propagación. Aunque los resultados son comparables con niveles fisiológicos, la revisión de la transmisión en el axón es necesaria para justificar los comportamientos dinámicos que se conocen de otras disciplinas.

This research aims to utilize dielectric spectroscopy in a frequency range of 1 to 8 GHz for the classification of 5 types of breast tumors. The experiment was conducted with data from 70 patients, considering surgeries such as mastectomies and lumpectomies. The measurement environment type was controlled, taking into account the extraction time, measurement pressure, and temperature. The final results showed that benign tumors have permittivity values below 35, while malignant tumors range between 40 and 60, with variabilities greater than 50% between each tumor type. These results highlight the effectiveness of these measurements in breast tumor classification, providing a valuable tool for rapid and accurate diagnosis and effective treatment, complementary to pathological examinations.

This work presents the measurement of permittivity in biological materials using an open-ended coaxial probe fabricated from a simple SMA connector. The study investigates liquids and biological tissues within the microwave frequency range. Results from measurements on polar reference liquids demonstrate satisfactory agreement with literature values and a commercial system, validating the proposed system's efficacy. Analysis of the employed models reveals that the capacitive model satisfactorily predicts the real part of permittivity, while the radiation model effectively predicts the imaginary part. Measurements on commercially acquired biological tissues show coherent and similar qualitative results to those obtained with commercial systems. This research contributes to the development of accessible and cost-effective methods for permittivity measurement in biomedical engineering and related fields.

This study focuses on the characterization of the dielectric stability of mixtures designed to simulate different levels of breast density and the presence of tumor tissues. These mixtures comprise common ingredients like water, oil, detergent, and gelatin, selected for their ability to emulate the electrical properties of breast tissues. The aim is to investigate whether these mixtures undergo any degradation in their dielectric properties over time, which could affect their usefulness as breast tissue models in medical applications. Results indicate that these mixtures exhibit stable dielectric properties over an observation period of approximately thirty days. Additionally, the study explores the modulation of material conductivity at low frequencies by adding sodium chloride, revealing a linear increase in ionic conductivity with salt concentration. This finding suggests that the conductivity of these mixtures can be adjusted to levels exhibited by mammary tissues, enhancing their versatility in simulating a wider range of breast tissue conditions.

In the electromagnetic analysis of large or complex environments the CAD of the entire platform is separately generated, typically. In that circumstances, independent meshes of separately generated CADs, does not conform in the boundaries, or forcing conforming leads to increasing complexity. Another examples where non-conformity between meshes appears are multiscale complexity, h-refinement, general assemblies of structures, more of then very useful in domain decomposition techniques. In Surface Integral Equation methods, we can lead with non-conformities using several techniques. We present several techniques for solving nonconformal assemblies of structures, based on, mainly, Discontinuous Galerkin and multi-trace techniques.

Este trabajo se centra en la combinación de las técnicas de subgridding y conformal, dentro del método FDTD, para abordar geometrı́as complejas, especialmente en aplicaciones de RCS para baja observabilidad y en contextos multiescala. Aprovechamos las ventajas de ambas aproximaciones para lograr resultados más precisos y eficientes. La incorporación de la técnica conformal mejora tanto la precisión como la eficiencia de los métodos subgridding, permitiendo reducir el número de niveles necesarios.

A reconfigurable liquid crystal (LC) based reflectarray (RA) designed for operation in the D-band from 105 to 125 GHz is numerically demonstrated. The device has a configuration of a high-impedance surface with a meta-array of 29×33 patches on a 2-mm-thick quartz substrate separated from the ground plane through a 40 μm-thick LC layer. The electric biasing of the LC-loaded RA unit cells is realized by introducing narrow inductive strips connecting neighboring patches in one imension. A novel LC composition with low dielectric losses (<0.003) and high dielectric anisotropy (>1.3) as been developed for operation at millimeter-waves. The results demonstrate a reflection phase tunability of 210° and low insertion losses of 2.5 dB. Furthermore, the device was demonstrated as a proof of concept for 1D beam-steering applications, exhibiting an operational bandwidth of 12 GHz.

The development of a Leaky-Wave Antenna based

on Bianisotropic Huygens’ Metasurfaces and using GAP waveguide

technology is presented in this work. The waveguide is

designed with horizontal polarization of the mode at 20 GHz,

different than the conventional vertical polarization. Additionally,

a uniform leaky-wave antenna designed just slotting the top

surface of the waveguide is compared with the same structure

but combining the slot with the Huygens’ metasurface which

change the radiation angle of the LWA to the desired broadside

radiation pattern.

We discuss the issue of identifying the forward/backward nature of the modes in bounded one-dimensional periodic structures. This identification relies on the possibility of adequately and uniquely defining the phase velocity in these types of structures. We propose a general definition of phase velocity for scalar one-dimensional waves and show that, according to that general definition, the voltage and current waves in lossless nonhomogeneous transmission lines with positive inductance and capacitance parameters are necessarily forward waves. In more general scenarios, we show that an appropriate definition of the phase velocity can still be found for electromagnetic waves with at least one linearly polarized field and that they also are necessarily forward waves if they propagate through media with positive permittivity and permeability.

Time domain simulations of electromagnetic problems are intrinsically interesting for engineering purposes, not only from the physical point of view but also from the computational effort. These approaches rely on a marching on time schemes where the field solution can be obtained from previous time steps in an increasing manner. However, each new sample requires computations with a small complexity (typically matrix-vector multiplications) but within a large approximation dimension, which clearly deteriorates the simulation time.

A model order reduction approach for finite element method in time domain (FEMTD) simulations for microwave devices using time as a parameter is proposed in this work. This methodology shows the possibility to solve time evolution problems in electromagnetics requiring a small computational effort. Indeed, the system matrices involved in the model order reduction technique are pretty small. This is in contrast to the large dimension matrices arisen in traditional FDTD and FEMTD approaches.

Several microwave circuits, such as an electromagnetic band gap structure and dielectric resonator filter, will show the capabilities and possibilities of this new approach for time domain simulations in electromagnetics.

The motivation behind the research lies in the necessity to identify indoor applications for 6G to contextualize and render practicality to the proposed work. While terahertz communication holds promise for achieving ultra-large bandwidths and Tbit/s speeds, the primary challenge lies in implementing transceivers suitable for integration into indoor and pico-cells WLANs for 6G applications. The proposed FSS architecture addresses these challenges by introducing a low-profile design that not only overcomes volumetric constraints but also reduces system complexity, thus enhancing cost-effectiveness and facilitating mass adoption across diverse technological domains. This innovative approach enables the implementation of dual polarization in both Co-Polar (CP) and Cross-Polar (XP) operations without the need for intricate multiport networks, thereby simplifying the system architecture and enhancing its versatility. The FSS design offers ultra-large bandwidth circular polarization fields in reflection mode, capable of providing two separate bands for each circular polarization, making both CP and XP operations feasible with minimal changes in phase, thereby paving the way for future 6G communications systems. The Design is manufactured and measured, presenting good relation with respect to the simulations

Currently, vortex beams with orbital angular momentum (OAM) are of great interest as they are a key element in increasing the capacity of communication links. This article presents an analytical study comparing the purity of OAM vortex beams generated using a metasurface illuminated with three different excitations. The transmissive metasurface has been designed to operate in the millimeter-wave frequency range, and consist of 33×33 two-layered H-shaped meta-atoms. The phase is implemented following the Pacharatnam-Berry (PB) principle. High OAM purity votex beams are obtained, with values of 75%, 90%, and 95% for the uniform, circular uniform and Gaussian excitations respectively confirming both the correct functionality of the metasurface and the effect that different excitations have on OAM quality.

Esta contribución explora la comunicación en banda de onda milimétrica, haciendo hincapié en el procedimiento de gestión de haz clave para los avances en 5G. Propone una antena lineal de 1x4 parches con barrido jerárquico de formación de haces en conjunto con la conformación adaptativa de haz. Las pruebas experimentales muestran una detección eficiente de fuentes, demostrando la reducción de pasos y una identificación rápida de las fuentes.

This work presents a validation of the CLAF-SIW technology to manufacture filters for the millimeter-wave frequency range. The studied filter is a bandpass filter composed of four cavities stacked and coupled by means of iris (a total of five iris are used). Each layer is composed of a PCB of commercial thickness. The iris layers are prototyped by metallizing the slot edges, while the cavity layers contain the CLAF-SIW structure using double mushrooms as an EBG structure. The filter is obtained immediately by simply adapting the effective width of the CLAF-SIW cavity to the reference cavity, for which the effects affecting this effective value have been studied. A prototype has been fabricated with good agreement between measurement, simulation, and the ideal cavity filter response for a 36 to 37.5 GHz passband. The small discrepancies are due to the differences in the real gap between laminates and manufacturing tolerances.

This paper presents a millimeter-wave (mmWave) 5G communication system incorporating a phased array antenna and a transceiver. The testbed features a custom-manufactured planar active phased array antenna with linear polarization, housing an 8$\times$8-element planar array BeamForming Integrated Circuit (BFIC). The 27 GHz transceiver, a prototype, is built using off-the-shelf components and engineered to upconvert signals from 3.5 GHz to 27 GHz. Furthermore, an emulation of a 3GPP-inspired gNodeB, based on the FR2 5G signal, is included. A comprehensive measurement campaign was conducted in an indoor environment. Additionally, a comparison with a passive antenna was conducted for 16-QAM modulation scheme. The obtained results support that the integration of a phased array antenna is a promising technology for the future of wireless communications.

In this paper, we introduce an innovative approach for determining the complex permittivity (ε) and permeability (𝜇) of magnetodielectric composites. Our methodology uses artificial neural network (ANN) modeling to determine these key parameters from S-parameter data collected at 2.45 GHz. These measurements are performed by a novel microstrip split ring resonator (SRR)-based resonant sensor, offering enhanced precision and reliability in the estimation process.

The advent of the new fifth-generation (5G) wireless network deployments is supposing a challenge for the service providers. The high losses and propagation mechanisms detriment inherent in the millimeter wave (mmWave) band combined with the complexity of real scenarios require simulation tools that take into account all the influencing factors. In this context, we have developed an innovative simulator for deploying, analyzing and optimizing new 5G wireless networks. After performing a non-stand alone (NSA) deployment, it is able to test its performance by studying mobile users along the simulation region. This paper summarizes its main functionalities and the most outstanding characteristics. In addition, a use case of real deployment and mobility analysis is presented as an example of the simulation tool capabilities.

In this paper, the communication antennas for LUR-1 mission are presented. LUR-1 is a satellite that will orbit at 500 km above the Earth with the purpose of taking images of the planet. This satellite uses the S and X Band to communicate with the ground station. The S Band antenna has TTC (Telemetry, Tracking and Command) functions while the X Band will be used for downlink data. Anteral has developed both antennas and the mission is programmed to be launched in June 2024.

Este trabajo presenta la caracterización de la conductividad efectiva de los materiales de fabricación aditiva utilizados para la manufactura de dispositivos para comunicaciones de alta frecuencia. Tanto el tipo de material, la porosidad, la rugosidad, como la oxidación disminuyen el valor de dicha conductividad llevando a un incremento en las pérdidas de inserción de los dispositivos fabricados. Para la caracterización se ha diseñado un resonador de cavidad en banda X sobre guía de onda rectangular y se ha medido el factor de calidad de diferentes realizaciones con técnicas y materiales diversos. Se han obtenido valores de hasta 17.70 $MS/m$ para materiales poliméricos metalizados y de hasta 5.32 $MS/m$ para aleaciones metálicas.

Empty Substrate Integrated Waveguides (ESIW)

integrate hollow 3D waveguides into printed circuit boards

(PCBs), thereby creating an empty waveguide with reduced

height while maintaining low cost, low profile, and easy in-

tegration. Several transitions have been proposed to connect

ESIW circuits to microstrip lines. However, these transitions

generally increase the complexity of the manufacturing process

and cannot be directly connected to measurement equipment.

Therefore, in this communication, a direct coaxial-to-ESIW

transition based on magnetic coupling is proposed. This structure

can be manufactured with reduced complexity, requiring only

simple cuts and metalization. An equivalent circuit model has

been proposed, which provides initial values for the transmission

parameters, and reduces the optimization time by 20%.

This article presents the design and manufacturing

of a fully metallic X-band bandpass filter in coaxial-line tech-

nology. The device is 3D-printed as a self-supported structure

without any dielectric inside. A short-circuit λ/4 parallel stub

bandpass filter an electrical connection between the inner and

outer coaxial-line conductors, and provide the required me-

chanical support for the self-supported 3D-printing process. To

enhance filter out-of-band performance, a second stage consisting

of a stepped-impedance low-pass filter is integrated, also using

coaxial-line technology. Both filters are designed separately and

then combined to achieve desired frequency specifications. A

prototype with a passband at X-band (between 8 and 12 GHz)

is manufactured using Selective Laser Melting, showing exce-

llent agreement between simulations and measurements. This

approach promises highly integrated, multifunctional monoblock

coaxial filters with additional benefits such as increased RF

shielding and protection against electrostatic discharge.

El efecto multipactor plantea un reto importante en los dispositivos de RF y microondas de alta potencia, como los filtros combline, ya que afecta a la integridad de la señal y al rendimiento del dispositivo. En este artículo, proponemos emplear un perfil de superficie corrugado para mitigar este efecto. Mediante simulaciones numéricas, demostramos que la introducción de una superficie corrugada suprime significativamente la aparición y propagación de descargas multipactor dentro de la estructura del filtro. El perfil corrugado altera eficazmente las condiciones propicias para la formación de avalanchas de electrones, aumentando así el nivel umbral de ruptura y reduciendo la probabilidad de degradación de la señal inducida por el multipactor. Además, exploramos la influencia de diversos parámetros geométricos del perfil corrugado en la supresión del efecto multipactor, proporcionando información sobre las consideraciones de diseño óptimas para mitigar este fenómeno. Nuestros hallazgos no sólo ofrecen una valiosa guía para el desarrollo de filtros combline robustos y fiables, sino que también contribuyen a una comprensión más amplia de las técnicas de supresión de multipactor en aplicaciones de RF y microondas de alta potencia.

In this work, the practical design of a Ka-band

diplexer and triplexer in half-mode groove gap waveguide (HMGGW)

technology is proposed. The first device is composed of

two bandpass HM-GGW filters, an E-plane T-junction and the

corresponding transitions to the input/output WR28 rectangular

waveguide ports. The second one has a manifold herringbone

configuration where three bandpass HM-GGW filters are directly

coupled on the common short line without the use of stubs.

In order to demonstrate the applicability of this technology, a

diplexer prototype has been successfully fabricated, showing inband

measured return and insertion losses of 21 dB and 0.87 dB

in the lower band, 16 dB and 0.86 dB in the upper band, and a

good isolation level (better than 32.5 dB) in the whole operational

frequency range. This good electrical behaviour demonstrates

that HM-GGW is an attractive technology for the design of high

frequency components, thus helping to reduce its size respect to

the equivalent component in the classical GGW technology.

Por hacer

En los últimos años, se ha observado un crecimiento exponencial en los nuevos sistemas de comunicaciones, entre los cuales se destacan las comunicaciones inalámbricas y espaciales. Este fenómeno ha generado un incremento significativo en los requisitos de los sistemas de radiofrecuencia. Este aumento no solo se refiere a la respuesta eléctrica de dichos sistemas, sino también a otros parámetros de importancia, tales como el peso, el coste, el volumen y la integrabilidad con otras tecnologías. Con el propósito de cumplir con estos requisitos emergentes, los circuitos integrados en substrato, específicamente los denominados Circuitos Integrados en Substrato Vacío (Empty Substrate Integrated Circuits (ESIC)), se presentan como una solución altamente prometedora. Estos circuitos son reconocidos por su bajo coste, ligereza y facilidad de integración, preservando al mismo tiempo su eficacia en términos de respuesta eléctrica. La principal ventaja de esta tecnología radica en la capacidad de incorporar tanto componentes activos como pasivos, así como antenas, utilizando el mismo substrato o combinando varios de ellos mediante procesos de fabricación planar estándar. La naturaleza vacía de estos circuitos posibilita la implementación de componentes de alto rendimiento sin comprometer las características previas. En este contexto, la presente tesis doctoral se propone como objetivo central la investigación, diseño, desarrollo y fabricación de antenas y nuevos componentes de microondas utilizando tecnologías vacías integradas en substrato, con enfoque en aplicaciones para satélites de dimensiones reducidas. La tesis abordará la exploración de nuevos componentes de microondas comúnmente presentes en las cargas útiles de satélites, tales como filtros, transiciones entre tecnologías planares, divisores, entre otros, así como antenas, tanto como elementos individuales, y en agrupaciones. Estas investigaciones se realizarán en el marco de las mencionadas tecnologías emergentes, con la finalidad de lograr un grado de miniaturización, dispositivos altamente eficientes, y de bajo perfil manteniendo sus características esenciales y obteniendo respuestas mejoradas en comparación con soluciones previamente conocidas. La combinación global de los dispositivos y antenas propuestos en la tesis doctoral abre nuevas posibilidades en las tecnologías vacías integradas en substrato, contribuyendo potencialmente a mejorar la capacidad, robustez y compacidad de los sistemas de comunicaciones emergentes

El tema de la tesis se centra en el diseño de la próxima generación de dispositivos IoT, los cuales requieren un cambio de paradigma debido a las exigencias de bajo consumo de un gran número de aplicaciones. En estos tres minutos se trata de manera general y divulgativa como utilizar la técnica de retrodispersión juntamente con señales de espectro ensanchado para cumplir los requisitos de bajo consumo sin sacrificar el rango de comunicación.

Presentación en video para el concurso 3MT, sobre el tema de mi tesis: antenas de onda de fuga basadas en metasuperficies.

La técnica de reconstrucción de imágenes mediante el uso de patrones de radiación distintos es ya conocida. Un tipo particular de patrones de radiación diferentes son aquellos que poseen un momento angular definido (OAM por sus siglas en inglés). El momento angular se define en función de la distribución de la fase. La principal virtud de los OAMs consiste en la inexistencia de interferencias entre patrones con distinto momento angular, lo que permite usarlos para el envío de información masiva (hasta 1,6 Tbits/s) simultánea a través de un mismo canal. Se presentan como una alternativa óptima para la técnica de imaging.

El principal objetivo de esta propuesta de tesis doctoral es diseñar estructuras capaces de generar OAMs, con el fin de explotar sus capacidades y particularmente fabricar sistemas de reconstrucción de imágenes en radiofrecuencia basados en metamateriales transmisivos o reflectivos que sean capaces de generar patrones de radiación independientes entre sí (OAMs) a través de una reconfiguración electrónica o mecánica.

Tecnologías como el 5G o el 6G hacen y harán posible el acceso total a internet en cualquier lugar del mundo, además a un coste bajo. Está tesis versa sobre nuevos métodos de fabricación para dispositivos milimétricos en comunicaciones por satélite

y la combinación de estos nuevos métodos como pueden ser las fabricaciones 3D con los sistemas clásicos de fabricación consiguiendo ampliar las ventajas de cada sistema y reduciendo sus puntos flacos.