Programa del congreso

This paper presents an innovative in-cabin wireless sensing system to enhance road safety and support autonomous vehicle technologies. Leveraging a modulated Frequency Selective Surface (FSS) and a millimeter-wave (mmWave) Doppler radar the system non-invasively detects driver head movements with high precision. By modulating the FSS at two distinct frequencies, it achieves privacy preservation, reduces computational complexity, and enhances noise immunity, offering consistent performance in varying lighting conditions. These features enable real-time processing, making the system ideal for integration into Advanced Driver Assistance Systems (ADAS). A prototype has been designed at 24 GHz. Experimental results demonstrate its effectiveness in distinguishing between attention and non-attention states, offering lower hardware complexity and superior performance compared to conventional approaches. By enabling timely interventions, this solution promotes safer driving and advances in vehicle safety monitoring.

This paper details how to exploit the introduction of time as a design variable to enhance the properties of conventional static (time-invariant) spatially-periodic metastructures such as Frequency Selective Surfaces (FSS). Here, we focus on communications scenarios, although most of the discussed concepts are also applicable in radar systems. We show that, by tuning the temporal period in time-modulated 1D metallic gratings, two different diffracted harmonic configurations mn and m'n' can propagate in the same direction (i) with different output frequencies (same incident angles and frequencies), (ii) with identical output frequencies (different incident angles, same incident frequencies), (iii) with identical output frequencies (different incident angles and frequencies). These results reveal the potential of space-time metastructures to act as beamformers and frequency mixers.

En este trabajo, se presenta una superficie selectiva en frecuencia basada en dipolos acoplados, diseñada para funcionar como reflector en la banda de 27 GHz. La estructura propuesta se distingue por su amplio ancho de banda y la posibilidad de controlar el mismo, lo que la hace adecuada para aplicaciones de alta frecuencia que requieren estabilidad espectral. A diferencia de otras superficies selectivas en frecuencia con geometrías más complejas, el diseño propuesto ofrece una alternativa sin comprometer su desempeño electromagnético. Adicionalmente, se ha desarrollado un modelo circuital equivalente que representa con precisión el comportamiento de la estructura, proporcionando una herramienta eficaz para su optimización y diseño.

This article presents a semi-analytical technique to model space-temporal periodic structures modulated by pin diodes. The structure is 3-dimensional from the perspective of the periodicity. An analysis in terms of Floquet harmonics is carried out, where the field at the discontinuity is previously estimated. Validations in terms of previous approaches encourage the use of the model, which has the potential and simplicity to characterize future space-time structures and metasurfaces.

This work presents the design of a full-metal 3D unit-cell for RIS-based applications relying on the use of a loaded slot ring. The load is a shorted stub in the inner conductor of the ring, whose angular position can be changed mechanically. Thanks to this mechanical rotation, two different phase states of the reflection coefficient of the unit-cell, separated by 180º, can be induced (equivalent to a 1-bit configuration RIS). The cell operation provides large-bandwidth capabilities, centered in 16 GHz with a 180+/-30º phase difference on a relative bandwidth of 36.9% (from 12.6 GHZ to 18.5 GHz). The designed unit-cell is then simulated in an array configuration for beam steering, where its instantaneous bandwidth has been estimated for different steering angles.

This communication presents a novel transition from an empty substrate integrated coaxial line (ESICL) to an empty substrate integrated waveguide (ESIW). Implemented using a standard planar manufacturing process, this transition facilitates the development of comprehensive microwave systems that integrate multiple technologies. The design methodology is detailed, and two ESICL-to-ESIW transitions for the Ku- and K-bands demonstrate simulated return losses better than 30 dB across their entire frequency ranges. To confirm feasibility, a back-to-back ESIW-ESICL-ESIW transition is fabricated and tested, achieving return losses greater than 19 dB and insertion losses below 0.45 dB.

In this work, corona discharge breakdown threshold in empty substrate integrated waveguide (ESIW) bandpass filters is studied. The objective is the analysis and improvement of the peak power handling capability of filters in this new technology. First, areas where the electric field has its maximum intensity are detected, and then a strategy based on introducing dielectric cylinders in these zones is applied. Simulation results show that, for a third order bandpass filter centered a 10,5 GHz and with 100 MHz of bandwidth, corona discharge breakdown thresholds between 2.2 and 3 dB higher than those of a standard ESIW bandpass filter are achieved.

This paper presents the design and analysis of an L-band antenna for Automatic Dependent Surveillance-Broadcast (ADS-B) signal reception from Low Earth Orbit (LEO) satellites at 1090 MHz. The proposed antenna is based on a six-faced prismatic array configuration that achieves omnidirectional coverage in the azimuth plane. Each face integrates a compact 4x2 subarray built from a miniaturized circular microstrip patch element with T-shaped extensions and dual-port excitation for circular polarization. The unit cell exhibits a reflection coefficient better than -10 dB and an axial ratio suitable for mitigating ionospheric rotation effects. Experimental validation of a 2x2 prototype confirms the simulated results, with a measured gain of 11.27 dB and a-3 dB beamwidth of 46.3 degrees. This preliminary design demonstrates the feasibility of integrating compact, high-performance antennas for spaceborne ADS-B reception systems, supporting global air traffic surveillance in remote and oceanic regions.

In this work, a new topology of waveguide combline filters based on flat metallic strip resonators is presented. The main advantages of this new topology are the ability to implement transmission zeros (TZ) and low-cost practical realization. Furthermore, the position of the TZs can be controlled using offset resonators, thus achieving more selective filter responses. The design of several bandpass filter examples with finite-frequency TZs is also discussed. Two different commercial software tools (Ansys HFSS and CST Studio Suite) have been used to verify the correct operation of the designed filters, thus validating both the proposed topology and the employed design procedure.

Esta contribución explora diferentes enfoques para las pruebas de alta potencia de elementos radiantes en condiciones de alto vacío. Las pruebas multipactor en dispositivos conducidos son una práctica estándar de la industria, sin embargo, las pruebas de elementos radiantes aún no han alcanzado ese nivel. La necesidad de validar los elementos radiantes en condiciones de vacío proviene del proyecto europeo Galileo de la Comisión. El trabajo se centra en los enfoques de trabajo y describe ideas inadecuadas para este propósito. En este trabajo se presentan dos soluciones de trabajo. La primera es una cámara de vacío transparente de RF colocada dentro de una cámara anecoica equipada con absorbentes de alta potencia. El segundo enfoque consiste en utilizar baldosas de ferrita dentro de una cámara de vacío estándar.

Las antenas eléctricamente pequeñas, que resultan una necesidad en determinadas aplicaciones y frecuencias, suponen un desafío de diseño debido a su impedancia altamente reactiva y su baja resistencia de radiación. El uso de técnicas de adaptación tradicionales basadas en elementos pasivos impone un trade-off entre ancho de banda y eficiencia de radiación. Sin embargo, el uso de elementos activos permite superar los límites de Bode-Fano-Youla y obtener anchos de banda elevados sin con ello reducir drásticamente la eficiencia de la antena. En este paper se utiliza esta idea para adaptar un array logoperiódico de 2.3 GHz empleando un conversor de impedancia negativa para obtener elementos non-Foster (condensadores e inductores negativos) y crear una nueva banda a 300 MHz.

Wireless Power Transfer (WPT) plays a critical role in several future applications such as IoT sensors and medical implants. Efficient antennas are essential components to have higher performance for the WPT system working with a larger coverage area. This paper presents a novel high-gain omnidirectional conical dielectric resonator antenna (DRA) designed for WPT systems operating at 5.8 GHz. The proposed DRA features a conical geometry led by a short-circuited parasitic metallic circle patch, which enhances current distribution and significantly improves radiation efficiency. This enables the achievement of an omnidirectional pattern with a high peak gain of 4.26 dBi and high with a low ripple level below ±0.3dB. The antenna achieves a 4% impedance bandwidth and maintains omnidirectional radiation patterns in the azimuth plane with an impressive total efficiency of 95.1%. This design offers a compact and efficient solution for modern WPT applications requiring robust and uniform coverage.

This article presents the design and analysis of a floating patch antenna with symmetrical radiation pattern using dual-rod feeding. The design of floating patches using air as a dielectric and fed through a copper rod not only enables high efficiency and bandwidth but also significantly simplifies the manufacturing process. However, antennas designed with a single copper rod feed do not have a broadside radiation pattern due to the asymmetry of the feed, which is a known issue in patch radiation patterns and complicates its use in different applications. At the same time, the proposed symmetric feeding with two posts will produce an additional benefit, and the resulting floating structure will be more stable and robust, being the antennas developed with the feeding that is proposed in this contribution suitable for applications where vibrations could damage the patch supported with a single post. Therefore, the objective of this article is to present a floating patch design with a pure broadside radiation pattern that facilitates the use of this antenna in different applications, especially in the design of antenna arrays with a broadside radiation pattern or in devices where a robust layout is required.

This paper introduces the design of a circularly-polarized Gap Waveguide-based antenna. The design features a compact all-metal two-layered structure. It achieves circular polarization in a dual-band configuration, from 37.5 to 42.5 GHz and from 47.5 to 52.4 GHz, showing Axial Ratio values below 1.5 dB. The design includes a transition from a WR-19 standard waveguide to the Ridge Gap Waveguide that feeds the radiating structure. Regarding the return losses, values higher than 10 dB are achieved from 37.5 to 52.4 GHz. This unit cell antenna achieves gain values varying between 8.5 to 11.9 dB across the bands of interest.

Este trabajo presenta una técnica iterativa de muestreo adaptativo para medidas en rango plano con un brazo robótico. Esta técnica reduce el número de muestras sin disponer de información a priori de la antena. El método emplea una transformación matricial de campo cercano a campo lejano y Descomposición en Valores Singulares (SVD) para proyectar el campo en la apertura sobre sus modos dominantes. En cada iteración, se calcula y se añade un nuevo conjunto de puntos de muestreo que maximiza la variación en los coeficientes modales. La técnica ha sido validada mediante simulación a 30 GHz y mediante un ejemplo aplicado a una medida real a 22 GHz, obteniendo un 90% de reducción y un nivel de error de −47 dB en simulación, y 86% de reducción con un nivel de error de −38 dB para el ejemplo aplicado a medida real.

Energy efficiency has emerged as a cornerstone in the development of b5G/6G networks, particularly within the framework of Open Radio Access Networks (O-RAN). This paper presents a monitoring and prediction system designed to reduce the energy consumption of critical O-RAN components, namely the Central Unit (O-CU) and Distributed Unit (O-DU). The proposed approach leverages the MAPIE algorithm to generate robust energy consumption forecasts with theoretically grounded prediction intervals, allowing for real-time network resource optimization without compromising service quality. Experimental validation was conducted in a disaggregated commercial O-RAN environment, emulating realistic operational conditions, supporting the identification of consumption patterns and enabling proactive network management. The proposed system serves as a foundation for intelligent, energy-aware management strategies in future mobile networks, paving the way for automated decision-making in Service Management and Orchestration (SMO) systems.

The fifth generation of networks arrived to provide not only enhanced network capabilities but also to establish unprecedented security and privacy levels aimed at protecting end-user security and privacy. While standardization bodies have defined the required security mechanisms, there is a lack of systematic approaches for evaluating the security measures applied by 5G networks and their resiliency under fuzzing attacks. In fact, security compliance certification of any given interface is only required when there are enough offerings from the testing providers, according to TS 33.117 [2]. Currently, this approach leaves multiple critical surfaces out of the testing scope. To address this gap, we propose a complete framework built on open-source software to assess the robustness of 5G base stations in real over-the-air environments, enabling a comprehensive evaluation of security and privacy protections provided to end users.

Brain-Computer Interfaces (BCIs), are revolutionizing human-machine interactions, providing remarkable advancements across medical, industrial, educational, entertainment, and security domains. Despite BCIs' great potential, they simultaneously raise critical ethical concerns regarding user data privacy and their Neurorights, which aim to safeguard individuals against the risks of emerging neurotechnologies, especially as they become increasingly available on the market. Utilizing a comprehensive literature review and implementing a passive attack on two commercial BCI devices, the study reveals critical vulnerabilities during all the phases of the system. Our findings underscore the urgent need for robust cybersecurity frameworks, including Privacy-by-Design strategies. To address this problem, we designed a scoring framework based on the Bluetooth standard, that guides manufacturers and helps regulators, guaranteeing the safe adoption of BCIs. The proposed solution aims to enhance the security of the pairing process on BCI devices, thereby ensuring user neural data integrity and protection.

Garantizar la confianza en las redes 6G es crucial para mantener la seguridad, la fiabilidad y la idoneidad de muchas aplicaciones. La evaluación de la confianza requiere validación, integridad y protección contra manipulaciones. Este artículo explora cómo puede aprovecharse la tecnología blockchain para la evaluación de la confianza a prueba de manipulaciones en las redes 6G. Analizamos las ventajas de utilizar blockchain para una evaluación de la confianza transparente y descentralizada, destacando su resistencia a los ataques y su capacidad para garantizar la integridad de los datos. Además, abordamos los retos de aplicar blockchain en diversas aplicaciones 6G, como la utilización de recursos, la respuesta en tiempo real y la escalabilidad. El artículo también hace hincapié en el papel de los contratos inteligentes en la automatización de la gestión de la confianza y el almacenamiento seguro de la información relacionada con la confianza dentro de la blockchain, ofreciendo un enfoque innovador para mejorar la seguridad y la rendición de cuentas en las redes de próxima generación.

Traducción realizada con la versión gratuita del traductor DeepL.com

Trust and security are paramount in the emerging landscape of 6G networks, particularly as these systems become increasingly decentralized and heterogeneous. Accurate node reputation prediction is essential for maintaining robust network functionality in such environments, enabling the identification of trustworthy nodes and the mitigation of malicious behaviors. In this work, we present a novel reputation evaluation framework tailored for 6G scenarios, combining Graph Neural Networks (GNNs) for representation learning with Support Vector Machines (SVMs) for effective reputation classification. This hybrid approach captures both the structural and behavioral dynamics of network nodes, offering resilience against common threats, such as Sybil attacks and collusion. Our method addresses critical challenges in reputation prediction, including dynamic node behavior, data sparsity, and scalability across massive device deployments. Experimental results demonstrate that our GNN–SVM pipeline significantly enhances reputation prediction performance, offering a scalable and intelligent trust management solution for the next generation of 6G networks.

En este artículo se resumen las especificaciones técnicas de radio distribuida que se implementan en el proyecto europeo 6G-REFERENCE (6G - Hardware Enablers for Cell Free Coherent Communications and Sensing).

Este artículo describe el análisis, diseño y construcción de un dispositivo de microcinta capaz de detectar hidrógeno a frecuencias de microondas. La estructura propuesta consiste en una línea de transmisión tipo microstrip híbrida de 10 cm de longitud, en la que parte de la línea de cobre (Cu) se sustituye por una lámina de paladio (Pd) de 10 nm de espesor. Para un dispositivo con una sección de Pd de 2 cm de longitud, expuesto a un 1,6 % de hidrógeno a una presión de 0,4 bar en nitrógeno gaseoso, la detección se realizó midiendo los cambios producidos en una de las resonancias del parámetro de dispersión S21 en la región de frecuencias de alrededor de 3,2 GHz. Los resultados obtenidos demuestran que la detección de hidrógeno es posible mediante la implementación de bajo costo propuesta. Este hallazgo abre la posibilidad de construir sensores de hidrógeno simples mediante la incorporación de películas ultrafinas de Pd en circuitos de microondas planares.

Este trabajo describe brevemente la concepción y el desarrollo del hardware y el software integrado en el nodo sensor inalámbrico de dimensiones compactas e independiente, llamado SensorQ, sus dimensiones y peso finales son 200 × 80 × 60 mm y 0,422 kg, respectivamente. El nodo SensorQ propuesto se desarrolló específicamente para detectar agentes de guerra química (CWA), con especial el sustituto del gas Sarín, conocido como dimetilmetilfosfonato (DMMP). Además, se describen la arquitectura del sistema, los protocolos de comunicación empleados, el diseño del cabezal sensor óptico y los resultados de la validación experimental realizada en un entorno de laboratorio. Los hallazgos experimentales demuestran el potencial para detectar vapor de DMMP (en concentraciones de 10, 150 y 400 ppm) en el aire utilizando el cabezal sensor óptico propuesto. Esperamos que el nodo de sensor inalámbrico SensorQ sea un candidato prometedor para integrarse en redes de sensores inalámbricos (WSN) en aplicaciones de defensa, ya que está diseñado para detectar CWA en escenarios complejos.

The development of devices that integrate sensing and communication is an area of increasing interest in research on connectivity systems for autonomous vehicles. This paper experimentally implements this concept using commercial radars. By utilizing the capabilities of two radars designed exclusively for sensing, the radar signals are modulated in such a way that one radar can transmit encoded information about its own sensing data, while the other radar receives, decodes, and analyses the information. The communication showed error free ranging from 0 to 45 m, in an outdoor environment with realistic conditions.

Many cryogenic missions for space observation have been launched in the past. In all of them, it was key to insulate the observation devices from thermal and electromagnetic perturbations. A solid understanding of materials and signal propagation is therefore essential to achieve full spectral isolation for cryogenic systems. This work introduces a non-resonant electromagnetic characterization method to extract permittivity and loss in dielectric materials at extreme temperatures. The authors design, simulate and validate a double microstrip transmission line and implement a flexible extraction method to measure permittivity over a wide frequency range, using materials such as CuClad 250, ROGERS 4350B and FR-4. Albeit refinements to the extraction process and comparison with real measurements in a cryogenic setting are possible, the resulting system is shown to be consistent and reliable across all simulations.

In this contribution, the shaping of a dispersive chessboard metasurface on a real target is studied. For this purpose, a model of an Unmanned Aerial Vehicle is used to analyze the critical areas that generate a larger radar cross section, which are the flat areas. However, edges between these areas can be problematic, which is why they are part of this study. In this aspect, it is verified that their presence is not a problem in terms of radar cross section reduction. On the other hand, the fuselage of the target under study is curved, so it is also necessary to analyze curved shaped surfaces. In this line, the original flat metasurface has been adapted to different cylindrical curvatures, achieving for all cases similar results to those obtained with the flat design.

This communication presents a numerical assessment of materials with inclusions concerning radar observability. For this, the Rozanov limit, obtained for homogeneous metal-backed materials, is used as a reference. The results, obtained from numerical modeling of materials with inclusions treated as dispersive effective media, suggests high versatility in achieving tailored radar responses

The analysis of electromagnetic (EM) wave propagation in an inhomogeneous, magnetically confined plasma is essential for nuclear fusion, particularly for ion and electron heating. This paper presents EMWAVE, a finite element code that simulates EM wave propagation in an anisotropic plasma by solving the Helmholtz equation in the frequency domain. The solver supports linear and quadratic elements and efficiently models complex domains. Various dielectric media and tokamak-relevant configurations have been benchmarked, demonstrating the code’s reliability. EMWAVE incorporates the cold plasma permittivity tensor, showing excellent agreement with the well-established ERMES code and theoretical predictions for tokamak cutoffs. Developed as a standalone tool and integrated into the HPC framework Alya, it aims to support reactor-scale simulations via a digital twin approach. Future work includes implementing a hot plasma permittivity tensor to capture wave-particle interactions and extending the model to 3D reactor geometries.

This work presents a method for free-space electromagnetic characterization of thin films in the X and Ku frequency bands implemented inside a compact anechoic chamber (80MHz-18GHz). The setup consists of two horn antennas to study transmission and reflection of samples using two configurations. The configuration for reflection measurements has the sample placed on a conductive support to study reflection as a function of the angle of incidence. Alternatively, the transmission configuration has both antennas pointing at the sample, which is positioned between them in a linear arrangement. Moreover, the experimental setup has a laser system for antenna and sample alignment to ensure maximum precision. The design's versatility was accomplished by using 3D-printing personalized supports, anchors and other accessories. The system was optimized via electromagnetic finite element and ray-tracing simulations. Preliminary results show potential for future usage of the proposed setup when developing absorptive materials.

This study presents experimental evidence and model comparisons demonstrating the ability to tune microwave absorption in magnetodielectric composite systems. Measurements of complex permeability, permittivity, and reflection loss at microwave frequencies were conducted in an anechoic chamber. The research focuses on mono- and bi-layer composites composed of a dielectric matrix and magnetic fillers. Novel considerations based on random magnetic anisotropy behavior were employed to design enhanced magnetic fillers. The high sensitivity of absorption capacity to design parameters is highlighted, along with their non-linear dependence. Additionally, the importance of proper fabrication for optimal electromagnetic performance is discussed based on the collected data. These findings underscore the potential for tailored design strategies in developing advanced materials for microwave applications.

Los incendios forestales representan riesgos graves para la seguridad humana, la estabilidad económica y los ecosistemas, con un impacto intensificado por el cambio climático. Este trabajo investiga la estructura causal entre los sistemas terrestres y los incendios forestales mediante modelos basados en datos. En este trabajo, se considera el algoritmo de Peter–Clark con independencia condicional momentánea (PCMCI) para estudiar los vínculos causales en series temporales de datos. A diferencia de estudios anteriores enfocados en la presencia de incendios [1], este trabajo permite simular y predecir cómo los cambios en las variables de entrada afectan el tamaño del área quemada, proporcionando información valiosa sobre la magnitud de las interacciones directas e indirectas.

Plastic pollution poses a global environmental challenge with profound ecological and societal impacts. Hyperspectral imaging (HSI) combined with polarimetry offers a promising approach for detecting, classifying, and quantifying plastic waste in aquatic environments. This study presents the design of a system to capture polarimetric spectral hypercubes and employs spectral unmixing techniques to identify plastic components in complex scenes. In addition to integrating polarization into the data acquisition pipeline, we investigate its effects on spectral analysis and material discrimination, providing insights into its utility for enhancing plastic detectability.

This paper proposes a Low Earth Orbit (LEO) Positioning, Navigation, and Timing (PNT) system leveraging LoRaWAN signals. We introduce a framework for processing LoRa transmissions in LEO scenarios, featuring a robust method for Doppler shift and time-delay estimation. To address collision-induced performance degradation caused by the ALOHA-based medium access protocol, we present an interference mitigation strategy. The system is evaluated through extensive Monte Carlo simulations, demonstrating reliable performance in single-signal conditions. However, results indicate significant performance degradation in collision scenarios. This work provides foundational insights into LoRaWAN-based LEO PNT systems and their challenges in practical deployments.

As an electromagnetic wave propagates through the ionosphere, it experiences scintillation, group delay, and dispersion, leading to signal distortion and potential performance degradation in radar applications. These effects introduce random fluctuations in intensity and phase, impacting the accuracy and reliability of spaceborne radar sounders used for subsurface probing, particularly in the VHF band. This study employs a physics-based ionospheric model to analyze the impact of scintillation, group delay, and dispersion on VHF radar sounder signals. Using the phase screen model derived from Rino’s theory, we simulate wavefront perturbations under varying ionospheric conditions. The results provide insights into the influence of ionospheric turbulence on VHF radar observations, aiding in the development of strategies to mitigate these effects and enhance radar data interpretation.

In this paper, we present the design, implementation, and validation of a complete software-defined radio (SDR)-based receiver for Orbcomm Low Earth Orbit (LEO) satellite signals, aimed at extracting observables for satellite-based positioning. The Orbcomm constellation, operating in the VHF band, provides unique opportunities for robust positioning in challenging environments due to its low attenuation and high signal power. We detail the system architecture, including hardware setup, signal acquisition, and software processing. Experimental results confirm the receiver’s capability to track and process live satellite signals, with close alignment between extracted observables and theoretical models derived from orbital ephemerides. We further evaluate the constellation’s geometric dilution of precision (GDOP) under single-satellite scenarios, highlighting limitations in positioning accuracy due to the inherent geometry. This work lays the foundation for future developments in real-time LEO satellite positioning and hybrid navigation systems.

In this work the wireless channel between 110 and 170 GHz has been measured using a vector network analyzer and virtual arrays in an indoor environment and in a line-of-sight situation. The path loss and root mean squared of the delay spread have been extracted from the measurements at different locations for the whole and for several sub-bands: 130-134 GHz, 141-148.5 GHz, 151.5-164 GHz. The floating-intercept model of the path loss has been obtained for all cases and the trend of root mean squared of the delay spread respect the distance has also been estimated.

This paper presents a modified ridge-gap waveguide capable of attaining highly dispersive wave propagation. This new waveguide allows the design of leaky-wave arrays with a fast frequency-scanning rate. The modification involves inserting deep corrugations into the central ridge, which enforce the slow-wave regime and enhance the slope of the phase constant with respect to frequency. Based on this new waveguide, a design example of a linear shunt slot array has been proposed. Consisting of a relatively simple structure, it can cover a field of view of +-30º within a 1-GHz bandwidth. These results confirm the promising properties of the proposed waveguide for designing backward-to-forward fast-scanning all-metal leaky-wave arrays in the millimeter-wave band

he increasing demand for high-performance

wireless communications in vehicular environments has led to

the development of massive MIMO (mMIMO) systems to

enhance capacity and spectral efficiency. This paper

investigates the impact of different MIMO antenna

configurations in vehicular scenarios, focusing on their effect on

system capacity and correlation properties. A measurement

campaign was conducted using the MaMIMOSA massive

MIMO channel sounder at 5.89 GHz with 80 MHz bandwidth.

The analysis considers various receiving antenna

configurations, including omnidirectional and directive patch

arrays, placed on a vehicle moving under line-of-sight (LOS)

and non-line-of-sight (NLOS) conditions. The results highlight

the influence of antenna selection on the achievable capacity,

spatial correlation, and the overall performance of vehicular

mMIMO systems. The findings contribute to optimizing

antenna designs for 5G and beyond vehicular communication

systems.

EM waves carrying orbital angular momentum (OAM) have been investigated in relation to its generation and transmission, with increasing interest in their usage and integration into modern communication systems. In the radio domain, the employment of a uniform circular array (UCA) featuring a consistent phase shift between neighboring elements is the most common technique employed in the literature to generate OAM carrying waves. Although offering an under-standable solution, the consistent phase shift may not guarantee pure OAM generation and isolation between the different modes when interested on capacity increase with orthogonal multimodal solutions. In this work, the orientation of the elements in the antenna array is reviewed concerning collinear and radial arrangements of its elements, briefly analyzing the generation and transmission performance of different OAM eigenmodes, prioritizing short-range communication use cases. With respect to the latter, this report also addresses considerations about the performance evaluation of different OAM modes in the absence of clear LOS visibility under the aforementioned geometries

Este artículo presenta el diseño de un sistema de antenas reconfigurable con capacidades de conformación y conmutación de haces para aplicaciones de comunicaciones móviles 5G en las bandas S y C. El conjunto propuesto está optimizado para cumplir con los exigentes requisitos de las actuales redes 5G, incluyendo altas velocidades de datos y baja latencia. Además, mediante el ajuste dinámico del diagrama de radiación el sistema permitirá apuntar el haz hacia usuarios específicos o mitigar interferencias. El conjunto puede utilizarse, en combinación con técnicas de conformación de haz adaptativas, para mejorar la cobertura y la fiabilidad de la señal en entornos urbanos densos, donde el mecanismo de conmutación de haz permite la gestión eficiente de los usuarios. Los resultados de la simulación muestran que la antena antena presenta una ganancia moderada en las bandas S y C, lo que la hace adecuada para su integración en estaciones base 5G. El trabajo proporciona una solución versátil para los sistemas de comunicación de próxima generación, contribuyendo al desarrollo de redes 5G más robustas y eficientes.

The vision for 6G is built on the need for predictability, reliability, and time-sensitiveness (i.e. deterministic networking), yet achieving deterministic communication across diverse network domains remains challenging. PREDICT-6G addresses this gap by pioneering an AI-driven, multi-domain framework that integrates deterministic networking principles across heterogeneous infrastructures. By combining a Multi-Domain Data Plane (MDP) with an AI-driven Multi-Stakeholder Inter-Domain Control Plane (AICP), the project enables seamless orchestration of end-to-end deterministic services, ensuring stringent latency, reliability, and synchronization across 3GPP (B5G), TSN, DetNet, and Wi-Fi technologies.

This paper reviews the key highlights of PREDICT-6G and introduces the results obtained.

Next-generation wireless networks will integrate sensing and communication, enabling intelligent and perception-driven connectivity. The MultiX approach introduces the MultiX Fusion Perceptive 6G-RAN (MP6R), a framework that leverages multi-band, multi-static, multi-sensor, and multi-technology capabilities to enhance situational awareness and network adaptability. To address network heterogeneity, MultiX proposes a distributed architecture comprising the MultiX Perception System (MPS) for embedded sensing, the MP6R Controller (MP6RC) for network orchestration, and the Data Access and Security Hub (DASH) for secure multi-sensor data processing. As a proof of concept, we present the Multi-Layer Digital Twin for Industrial Manufacturing, demonstrating how contextual data optimizes decision-making and real-time network adaptation. By integrating sensing across the RAN, MultiX transforms wireless networks into active perception platforms, supporting applications such as autonomous systems, smart manufacturing, and environment-aware wireless optimization,paving the way for future 6G networks.

This work presents a perspective on addressing the underutilization of computing resources in FPGA SoC devices deployed in 5G radio and edge computing infrastructure. The initial step in this approach involves developing a resource management layer capable of dynamically migrating and scaling functions within these devices in response to contextual events. This layer serves as the foundation for designing a hierarchical, data-driven micro-orchestrator responsible for managing the lifecycle of functions in FPGA SoC devices. In this paper, the proposed resource management layer is utilized to reconfigure a function based on events identified by a computer vision edge application.

Vehicular communications are expected to become one of the services that will benefit the most from 5G networks. The low latency and unprecedented high data rates 5G is expected to provide are a key enabler for new vehicular services. However, there are still different topics hindering its global adoption. For instance, certain cellular coverage holes may prevent having continuous V2X services as tele-operated driving. Similarly, situations such as traffic congestions can drain radio resource availability. In this context, the 6GTWINROAD-MNO project aims to investigate how to design the control plane of future 6G V2X network slices. Particularly, in this paper we merge the network exposure APIs defined in the 5G Core and the Open-Radio Access Network (O-RAN) architecture to provide a system that offers advanced exposure functions for future V2X services. In this context, we present two different exposure functions: predictive quality of service (QoS) for tele-operated driving and a digital twin for cooperative perception.

This paper provides an overview of the TRAINER-6G project, targeted to a special session devoted to spreading awareness within the URSI community on current research projects in 6G conducted by national academia and research centers. Since the project has just recently started, the paper describes its starting hypothesis and objectives. Besides, the link of the envisaged research with previous results is highlighted.

This study analyzed how 2.45 GHz radiofrequency (RF) radiation affects the immediate immune response in the RAW-264.7 macrophage cell line previously stimulated with the SARS-CoV-2 spike protein (CSP), bacterial LPS endotoxin or with both LPS and CSP. The RAW 264.7 cell line was continuously exposed for 24 hours in a GTEM chamber to a 2.45 GHz RF field at non-thermal SAR levels. Biological parameters of cellular metabolism such as cell viability and oxidative stress were studied by measuring nitrite levels, and progression of cell death was examined by measuring apoptosis and necrosis levels. The sustained effect of exposure to 2.45 GHz RF for 24 hours enhanced nitric oxide production and reduced cell death in macrophages stimulated with bacterial LPS. However, in the macrophages stimulated with LPS and CSP, exposure to RF did not modulate nitric oxide production or modify the progression of cell death.

Se presenta el diseño de un prototipo de sistema de exposición a radiofrecuencias de un modelo de laboratorio con gran potencial en el ámbito de la toxicología, poco a poco introducido para el estudio de los bioefectos de los campos electromagnéticos: el embrión del pez cebra. A pesar de que son varios los trabajos publicados con este modelo, la diversidad de configuraciones experimentales y de protocolos para la exposición RF del embrión en desarrollo dificulta la extracción de conclusiones fiables. Además, son escasos los estudios que evalúan la exposición mediante un análisis computacional y, en ningún caso, disponen de parámetros eléctricos específicos del embrión en desarrollo. Este trabajo presenta una propuesta integral, analizando el comportamiento de un sistema de exposición basado en una cámara reverberante y abordando, por primera vez, la evaluación dosimétrica del embrión del pez caracterizado eléctricamente. Se empleará para ello diversas técnicas y programas computacionales que permitirán comparar y validar los resultados, orientando la implementación futura del sistema de exposición a RF.

Hepatocellular carcinoma (HCC) accounts for 75% of primary liver tumors. Controlling risk factors and implementing screenings in risk populations does not seem sufficient to improve the prognosis at diagnosis. The development of a predictive prognostic model for mortality at the diagnosis of HCC is proposed. In this retrospective multicenter study, the analysis of data from 191 HCC patients was conducted using machine learning (ML) techniques to analyze the prognostic factors of mortality that are significant at diagnosis. Clinical and analytical data were gathered. Meeting Milan criteria, Barcelona Clinic Liver Cancer (BCLC) classification and albumin levels were the variables with the greatest impact on the prognosis of HCC patients. The ML algorithm that achieved the best results was random forest (RF). RF is useful and reliable in the analysis of prognostic factors in the diagnosis of HCC. The search for new prognostic factors is still necessary in patients with HCC

La pandemia de COVID-19 aceleró los avances en biología molecular y virología, facilitando la identificación de biomarcadores que diferencian los casos graves de los leves. Este estudio empleó inteligencia artificial y aprendizaje automático para analizar datos clínicos, epidemiológicos, analíticos y radiológicos de pacientes admitidos de manera consecutiva. Utilizando el algoritmo Random Forest, se procesaron más de 89 variables, logrando una precisión equilibrada del 92,61%. Los biomarcadores más predictivos de mortalidad fueron la procalcitonina, la lactato deshidrogenasa y la proteína C-reactiva, con especial énfasis en los infiltrados intersticiales observados en las radiografías de tórax y niveles elevados de dímero D. Estos hallazgos subrayan la eficacia del aprendizaje automático en entornos de emergencia para la identificación rápida de biomarcadores, mejorando en última instancia la precisión del pronóstico e informando estrategias de tratamiento personalizadas en pandemias emergentes.

Breast cancer is one of the most common types worldwide, and in many cases, it is treated with chemotherapy. To improve treatment follow-up, electromagnetic field-based technologies offer a non-invasive alternative for real-time monitoring. This study focuses on in vivo measurements of the dielectric permittivity of healthy, chemotherapy-treated, and tumor-affected breast tissues, aiming to assess their usefulness in monitoring treatment progress.

A coaxial probe (DAK 3.5) operating in the 1–8 GHz frequency range was used, following a standardized experimental protocol. Measurements were taken from 30 female volunteers. Results indicate an approximate 30% decrease in real and imaginary permittivity in breast tissue treated with chemotherapy compared to healthy tissue. Additionally, clear differences were observed between tumor and non-tumor tissues, suggesting the potential of this technique for therapeutic monitoring.

La tesis pretender dar solución a las principales dificultades en el diseño de dispositivos para frecuencias milimétricas. Para ello, se propone usar tecnologías planares como SIW, AF-SIW y CLAF-SIW, junto con técnicas avanzadas de fabricación (CNC, impresión 3D). La tesis se centra en diseñar, fabricar y caracterizar dispositivos radiantes con capacidad de conformado de haz espacial, usando propiedades geométricas, reconfiguración electrónica y metasuperficies. Los objetivos incluyen crear nuevos esquemas para elementos radiantes, desarrollar guías de onda para la estructura circuital, aplicar tecnologías emergentes y lograr dispositivos económicos, eficientes y con bajas pérdidas.

Existe una tendencia generalizada, tanto en España como en el resto del mundo, a la

exploración del uso de las tecnologías de fabricación aditiva para el desarrollo de

dispositivos de alta frecuencia para comunicaciones. Esta tendencia ha experimentado

un auge exponencial en la industria en los últimos diez años. Se pueden encontrar

ejemplos que utilizan como material de impresión metales o polímeros (como el ABS,

PLA, PETG) para la fabricación de guías de onda, filtros o antenas. Esta idea está acorde

a que existen numerosas tecnologías de fabricación de dispositivos de alta frecuencia,

su éxito comercial exige una gran eficiencia en términos de coste y producción masiva

junto con unas excelentes prestaciones de guiado. Así, la tecnología elegida se debe

adaptar a esta necesidad del mercado. Por otra parte, cada vez interesan más los nuevos

materiales poliméricos derivados de recursos renovables, y los materiales de altas

prestaciones, como las resinas dopadas con materiales cerámicos.

Hay cuatro categorías principales de tecnologías de impresión 3D: el modelado por

deposición fundida (FFF/FDM), las tecnologías basadas en la reticulación o “curado” de

resinas líquidas fotosensibles mediante láser o mediante luz ultravioleta (SLA, (M)SLA),

el sinterizado láser y la impresión 3D directa en metal mediante sinterizado (PBF).

Además de otras tecnologías como son el hilado de aleaciones por haz de electrones, el

laminado por capas, la litografía con foto-solidificación, y la proyección de material

aglutinante (PolyJet, MJF, etc.).

Independientemente del polímero que se utilice como material base de impresión, para

que este material pueda ser utilizado en la industria electrónica, necesita un proceso

posterior de metalizado. El Grupo de Aplicaciones de las Microondas (GAM), en el que

se desarrollará la tesis, cuenta con una patente sobre un proceso de metalización

autocatalítica para materiales poliméricos, y una amplia experiencia en el desarrollo de

dispositivos de alta frecuencia mediante fabricación aditiva.

Además, empresas como la suiza Swissto12 (www.swissto12.com) se dedican a la

fabricación aditiva de dispositivos de alta frecuencia, tanto dispositivos en guía de onda

como antenas, con dispositivos embarcados en satélites de la Agencia Espacial Europea

y de Saturn Satellite Networks. A su vez, la principal empresa fabricante de sustratos

para PCBs, la compañía ROGERS Corporation (https://rogerscorp.com), ha lanzado

recientemente al mercado sustratos imprimibles y metalizables; y ha establecido

también una alianza con la empresa Fortify para el desarrollo de dispositivos de

radiofrecuencia mediante impresión 3D.

El objetivo general de la tesis es el diseño y la fabricación de dispositivos de comunicaciones de radiofrecuencia para aplicaciones terrestres, marítimas y espaciales mediante fabricación aditiva con materiales no convencionales de altas prestaciones con y sin metalizado posterior.

Este objetivo general se desglosa en tres objetivos específicos:

1. Diseño de un amplio abanico de estructuras: dispositivos integrados e integrables, filtenas y arrays de antenas con líneas de alimentación, filtros sintonizables en tecnología guiada, estructuras en Groove Gap Waveguide, dispositivos modulares, lentes de estructura compleja. Optimizando las piezas y su ensamblaje.

2. Uso de nuevos materiales no convencionales y tecnologías de fabricación, tanto en la fabricación mediante tecnología de fabricación aditiva como los métodos sustractivos (CNC, fresado láser, etc.). Además, se experimentará con estructuras semiestocásticas (los metamateriales) para la modificación de las características mecánicas y electromagnéticas del material resultante.

3. Pruebas y medidas: caracterización superficial del metalizado, caracterización electromagnética de los dieléctricos fabricados, control dimensional, medidas electromagnéticas, etc.

Gracias al uso a fabricación aditiva frente a la fabricación sustractiva se permiten conseguir primeros prototipos funcionales con un peso reducido y con las prestaciones similares gracias al continuo desarrollo de las prestaciones de las tecnologías de fabricación 3D que está experimentando la industria. Eventualmente, esto permitirá desarrollar dispositivos cada vez con mejores prestaciones para las comunicaciones de radiofrecuencia.

Este trabajo presenta el diseño y la simulación en CST Microwave Studio Suite de una antena compacta que opera a 2 GHz, destinada a integrarse en una cápsula biomédica ingerible. El objetivo es demostrar una estructura miniaturizada que pueda incorporarse en un dispositivo diagnóstico pueda ser ingerido, similar a una cápsula médica, para futuras aplicaciones de monitoreo gastrointestinal (GI) basadas en interacción electromagnética. La antena está impresa sobre un sustrato RO3010™ y alimentada mediante una sonda coaxial, encapsulada completamente en una estructura biocompatible de PLA (Ácido poliláctico). Aunque las simulaciones se realizan en espacio libre, este trabajo sienta las bases para aplicaciones futuras en la detección de anomalías tisulares mediante contraste dieléctrico

El factor más limitante de cualquier sistema de comunicación es el canal de propagación sobre el que esté operando. Por consiguiente, es de vital importancia estudiar y modelar cómo responde el entorno de propagación en las distintas regiones del espectro radioeléctrico. Bajo el contexto del desarrollo de la tecnología 6G, el estudio y modelado del canal de propagación de las nuevas aplicaciones en las bandas milimétricas (mmWave, millimeter wave) y de los sub-THz (0.1 THz – 1 THz) es fundamental al ser una de las claves para cumplir con sus demandantes indicadores de rendimiento (KPI, key performance indicators). Las técnicas de medida del canal de propagación pueden basarse en sistemas en el dominio del tiempo o de la frecuencia. El modelado de canal clásico se puede llevar a cabo desde distintos espectros: determinista (e.g. ray tracing), estocástico/estadístico (e.g. Rayleigh) o híbridos. No obstante, gracias al auge de la inteligencia artificial (AI, artificial intelligence), nuevas aproximaciones de análisis y modelado basadas en aprendizaje máquina (ML, machine learning) o redes neuronales están surgiendo. Estas nuevas técnicas brindan un gran potencial apenas explorado para profundizar en el conocimiento del canal de propagación en las infinitas frecuencias y escenarios. Por consiguiente, el objetivo último de esta propuesta de tesis es la generación del conocimiento necesario para desarrollar nuevas propuestas de modelos y técnicas de análisis de canal en un muy amplio rango de frecuencias para los futuros sistemas de comunicaciones 6G. Este conocimiento efectivo del canal posibilitará el despliegue efectivo y eficiente de las futuras redes, aumentando su capacidad y su sostenibilidad energética. Para todo ello, se marcan los siguientes objetivos particulares: (i) la caracterización y el modelado de los nuevos entornos de comunicaciones para las diferentes aplicaciones verticales, (ii) el desarrollo de sistemas de medida que permitan una caracterización del canal de comunicaciones en frecuencias milimétricas y de sub-THz y (iii) el desarrollo de técnicas de procesado de señal e inteligencia artificial para la emulación de diferentes escenarios de comunicaciones.

La tesis que se está desarrollando trata sobre cómo utilizar las nuevas técnicas de fabricación para diseñar nuevos dispositivos pasivos para la llamada era de los satélites: en especial, fabricación 3D o fabricación aditiva, fabricaciones planares clásicas y las llamadas fabricaciones híbridas, las cuales utilizan elementos auxiliares como varillas, hilos, etc.

Los satélites de las próximas generaciones de satélites tienen unos requisitos mucho más exigentes en cuanto a prestaciones que los dispositivos clásicos; especialmente en lo que a volumen y peso se refiere. Dado que la tendencia actual es a que los satélites sean más livianos y reducidos; hay que intentar desarrollar nuevos dispositivos que cumplan estas directrices. Es por ello que el uso de dispositivos integrados en substrato permiten reducir en gran medida el volumen de las cargas útiles de los satélites. Los dispositivos integrados en substrato como lo son los ESIW (Guías de onda vacía integradas en substrato) y los ESICL (Líneas coaxiales integradas en substrato vacío) con un cierto recorrido ya en la literatura han sido una respuesta a esta problemática con muy buenos resultados: divisores, acopladores, etc. Sin embargo, hay una serie de limitaciones que tienen estos dispositivos, especialmente en cuanto a geometrías complejas o estructuras en altura (Z). Por toro lado, la impresión 3D o fabricación aditiva es un sector en auge y que viene a revolucionar la manera clásica de fabricar. Hoy en día ya se aplica en multitud de sectores como aeronáutica, odontología, restauración, implantes, etc. Del mismo modo hay diversos materiales usados para fabricación aditiva como plásticos, metales, madera, tejidos, etc. Es por lo cual, que la tesis ahonda en las nuevas técnicas de fabricación; especialmente la impresión 3D para poder desarrollar dispositivos de bajo coste y con altas prestaciones en dispositivos de microondas para satélites. Sin embargo, los altos requisitos en cuanto a tolerancias de fabricación hacen en ocasiones que la fabricación aditiva no sea suficiente para fabricar algunos dispositivos. Es por lo cual, que mediante la convergencia de ambas tecnologías; se pueden explotar los puntos fuertes de cada una de las tecnologías y reducir los puntos flacos. Es decir, combinar la parte planar o integrada en substrato con la de impresión 3D o aditiva. Si además, utilizamos elementos externos en combinación a los fabricados con impresión 3D o con fabricación planar podemos todavía mejorar estos resultados. Un ejemplo de esto es mediante postes; los cuales hacen a su vez las veces de alimentador y de soporte para antenas. Además, estas antenas consiguen valores excelentes en cuanto a ancho de banda y eficiencia.

Las comunicaciones acústicas subacuáticas (UAC, por sus siglas en inglés) se encuentran entre los canales de comunicación más desafiantes debido a su inherente selectividad temporal y frecuencial, causada por la dispersión Doppler y la dispersión en el retardo, respectivamente, especialmente en aguas someras. Este artículo presenta la implementación de un receptor SIMO OFDM (Single-Input Multiple-Output, Multiplexación por División de Frecuencia Ortogonal) que emplea modulación QPSK (Quadrature Phase Shift Keying). El sistema opera en un rango ultrasónico de banda ancha desde 32 kHz hasta 128 kHz. Se utiliza la configuración SIMO para explotar la diversidad espacial mediante la técnica MRC (Maximum Ratio Combining). Además, se incorpora codificación de canal utilizando un esquema LDPC (Low-Density Parity-Check) para mejorar la robustez de la transmisión. El rendimiento del sistema se evalúa utilizando señales reales obtenidas a partir de mediciones en aguas someras realizadas en el mar Mediterráneo.

El cáncer de mama es la principal causa de muerte en mujeres, y una de cada ocho sufre esta enfermedad a lo largo de su vida. La detección temprana y el seguimiento pueden reducir la mortalidad en hasta un 30%. El uso de la banda de microondas se ha propuesto para este fin ya que permite una monitorización más constante que las técnicas actuales, basadas en mamografías y exploraciones. Esta tesis se centra en la mejora de la resolución y la capacidad de penetración de los sensores planares para habilitar la detección de tumores no superficiales en estadios tempranos, cuando los tratamientos resultan más efectivos. Esto se ha conseguido mediante la realimentación de las pérdidas introducidas por el tumor utilizando un bucle activo. La estabilidad del sistema se ha garantizado mediante un diseño basado en técnicas de análisis de la estabilidad en sistemas realimentados como la función determinante normalizada (NDF), y el contacto directo se ha logrado utilizando un resonador en anillo complementario. Investigaciones futuras se centrarán en el desarrollo de una solución standalone combinada con inteligencia artificial para reducir los costes y realizar seguimientos personalizados de las pacientes.

Vídeo de Ignacio Esteban Lopez Delgado para el concurso "Tesis en 3 Minutos" que tendrá lugar en Tarragona durante la celebración del simposio naciona anual URSI-España 2025.

Partiendo de un objetivo bien definido, optimizar la absorción de microondas de láminas finas, en mi tesis estamos desarrollando diferentes métodos de caracterización electromagnética en espacio libre, medidas de pérdida de reflexión y predicción mediante aprendizaje automático.

Las Superficies Inteligentes Reconfigurables (RIS por sus siglas en inglés) emergen como una solución prometedora, permitiendo la reconfiguración dinámica de la cobertura mediante la adaptación al entorno y la orientación de los haces hacia los usuarios destino. Estas superficies pueden optimizar múltiples haces, realizar multiplexación en el tiempo y seguir a los usuarios en tiempo real, asegurando la calidad de la conexión y alineándose con las exigencias de ultrafiabilidad y baja latencia del 5G/6G. De este modo, las RIS no solo abordan la problemática de las zonas de sombra en la cobertura, sino que también incorporan la inteligencia y flexibilidad requeridas para las próximas generaciones de infraestructuras inalámbricas.

En este trabajo presentamos el diseño de un array de lentes geodésicas alimentadas por otro array de lentes geodésicas que permite generar 83 haces independientes en un rango de apuntamiento de 100° en el plano horizontal y 70° en el plano vertical. El escaneo en el plano horizontal se consigue mediante un array de lentes de Luneburg generalizadas geodésicas, mientras que para apuntar en el plano vertical se utiliza un conformador de haz compuesto por una lente mitad de ojo de pez de Maxwell. Ambas lentes se diseñan con un eficiente código de trazado de rayos y con el objetivo de mantener un alto nivel de cruce entre haces contiguos. La antena resultante es totalmente metálica y se puede fabricar de manera monolítica mediante fabricación aditiva directamente metálica.

This paper presents a novel design methodology for series-fed Continuous Transverse Stub (CTS) antennas, leveraging Ridge Gap Waveguides (RGW) as the feeding mechanism instead of traditional parallel plate waveguides. This approach is designed to introduce discrete phase shifts to each feed line, eliminating the conical scanning path associated with conventional series-fed CTS antennas and enabling scanning in the H-plane with constant azimuth. The RGW feeding network incorporates a fingerprint design to improve decoupling between adjacent channels, offering a compact, low-loss solution. The methodology is applicable to CTS arrays with arbitrary numbers of radiators and amplitude distributions. The performance of the proposed technique is validated by synthesizing two arrays with different amplitude distributions and demonstrating the feasibility of achieving H-plane scanning with the proposed feeding approach.

This work presents a fully-metallic 2×2 monopulse antenna array operating at 60 GHz, implemented in a single-layer configuration using Gap Waveguide (GW) technology. The proposed design achieves the generation of one sum (Σ) and two difference patterns (Δ_H, Δ_E) with a highly compact and low-profile architecture. Both the comparator network and the feeding cavities are integrated into the same metallic layer, while the top cover acts as the only closing structure, eliminating the need for complex multi-layer assembly or electrical contact between parts. By exploiting the phase inversion properties of GGW and RGW transitions, the antenna avoids the use of traditional hybrid couplers, thus simplifying the design and enhancing performance. Full-wave simulations validate the concept, showing high radiation efficiency and excellent pattern isolation. This approach paves the way for compact, low-cost and high-performance monopulse solutions in millimeter-wave applications such as radar, tracking systems and smart sensing platforms.

This work presents a comparative study of mul- tiple antenna array geometries for direction-of-arrival (DoA) estimation on-board Low Earth Orbit (LEO) satellite platforms. The performance of the Multiple Signal Classification (MUSIC) algorithm is evaluated under uniform and non-uniform array configurations, including Uniform Rectangular Arrays (URA), circular, concentric-ring, and sparse-derived structures such as nested, super-nested, and coprime arrays. All configurations are constrained to a common array surface to reflect realistic physical limitations on board LEO systems. The analysis focuses on the angular Root Mean Squared Error (RMSE) as a fun- ction of Signal-to-Noise Ratio (SNR) and the number of active elements. Results demonstrate that certain sparse configurations can achieve comparable or superior resolution to dense arrays with significantly fewer sensors, making them highly suitable for embedded systems. The study highlights the trade-off between spatial diversity, structural compactness, and DoA estimation accuracy, offering practical insights for array design in spatial signal processing applications.

³Cat-8 es una misión científica basada en un CubeSat de 6 unidades (6U) desarrollada por el UPC NanoSat Lab, con el monitoreo del centelleo ionosférico como objetivo principal. La misión incorpora varios sistemas innovadores, incluyendo una Antena desplegable de Zonas de Fresnel (FZPA), un Dispensador Integrado de PocketQubes (CuPID), un subsistema receptor GNSS de doble banda para experimentos de radio ocultación y reflectometría, y una cámara multiespectral polarimétrica para la observación de las emisiones de las auroras. Este artículo describe en detalle el diseño de la misión, el conjunto de cargas útiles, y el concepto de operaciones. Los datos recopilados por ³Cat-8 contribuirán a una mejor comprensión de los efectos ionosféricos en la propagación de ondas de radio y demostrarán la viabilidad de instrumentos compactos en plataformas tipo CubeSat.

The 23.6-24 GHz band is essential for measuring atmospheric water vapor, enabling weather forecasting, radar altimeter corrections, and other applications. However, the licensing of adjacent bands for the 26 GHz 5G communications band, specifically from 24.25 GHz to 25.25 GHz, has raised concerns about potential interference. Such interference could degrade the capability of passive Earth Observation measurements and impact scientific observations.

As part of the PocketQube proposed in the “IEEE Open PocketQube Kit”, the payload is integrated into a 1P PocketQube. The PocketQube has dimensions of 50x50x50 mm³, an average power consumption below 250 mW, and employs LoRa for communications. One advantage of the increase in RF frequency is the overall reduction in the size of RF components.

The growing significance of small satellites in space missions motivates the definition of streamlined CubeSat platforms that emphasizes cost-effective and flexible communication solutions. Central to this effort is the use of FPGAs, chosen for their capacity to integrate commercial off-the-shelf components while meeting stringent performance and reliability demands. By capitalizing on FPGA-based architectures, both rapid prototyping and reconfiguration capabilities can be achieved for on-the-fly updates. Due to its importance in communication satellites, a study of new useful techniques implemented in FPGAs is needed, including advances in signal processing, radiation-tolerant systems and reconfigurability. Through this work, we aim to advance the knowledge base for next-generation CubeSat communication systems, ultimately fostering more resilient, versatile, and scalable satellite networks.

This article presents the modular design of an antenna system for the I2Cat 6GStarlab satellite. The system covers seven communication bands: UHF, LoRa, S-Band NB-IoT (uplink and downlink), amateur X-band, and Ku/Ka bands for F2S services. Loaded monopoles are combined with circular patch antennas and arrays to achieve the required gains in each band. The system will be implemented in a 6-unit CubeSat structure provided by OpenCosmos, intended to orbit in SSO. The satellite will be part of novel non-terrestrial networks and will offer a 6G network experimentation service. Its launch is scheduled for autumn 2025 aboard a SpaceX Falcon 9.

This work describes the design and development of the front-end module for GNSS receivers of the 3Cat-8 satellite mission. The front-end operates in the L1 (1575.42 MHz) and L2 (1227.60 MHz) frequency bands and is intended for implementation in the latest satellite mission of UPC NanoSat Lab, an initiative of the Department of Signal Theory and Communications and the School of Telecommunications Engineering at the Universitat Politècnica de Catalunya (UPC). This project builds upon the work initiated by previous students. The design is based on a switching matrix concept to manage multiple GNSS signals coming from four different antennas (front, back, uplooking, and downlooking) and achieve the ultimate goal of this project: to create a design capable of providing PNT (positioning, navigation, and timing) information from the satellite and generate useful data to perform radio-occultation (GNSS-RO) and reflectometry (GNSS-R) experiments. In addition, a microcontroller-based system will manage the subsystem’s storage, communications, and control, interfacing with the onboard computer (OBC).

CubeSat missions increasingly rely on advanced communication subsystems to sustain vital links between the satellite and Earth. Despite rapid innovation in protocols, hardware, and ground systems, the existing literature remains fragmented, offering limited guidance for mission designers. This paper presents a comprehensive and structured review of contemporary CubeSat communications, based on the analysis of various missions within the sector. TT&C protocols, antenna design strategies, and software-defined radio (SDR) integration are examined and evaluated. Ground segment considerations are also explored, alongside notable real-world implementation examples. The findings aim to support future CubeSat deployments by highlighting scalable and resilient communication architectures suited to increasingly congested low Earth orbit environments.

El aumento de las enfermedades óseas debido al envejecimiento poblacional requiere la búsqueda de nuevas técnicas de implantes, como son los andamios óseos. En esta contribución se propone el diseño de andamios óseos autosensores que funcionan como sensores pasivos de microondas sin necesidad de electrónica adicional, a la vez que mantienen sus características estructurales y favorecen la regeneración ósea. Para ello, se diseña un resonador dieléctrico (RD) poroso que se puede fabricar mediante técnicas de fabricación aditiva (impresión 3D), resultando en una estructura personalizable y de bajo coste. Se propone una prueba de concepto mediante la que se observa que la simulación de la regeneración ósea produce un cambio en la frecuencia de resonancia y ancho de banda del RD poroso. Estos resultados experimentales demuestran la validez de esta técnica para conseguir una monitorización no invasiva, continua, en tiempo real y barata mediante radiación no ionizante para realizar el seguimiento del proceso de regeneración ósea.

This paper presents a study related to the implementation of realistic breast models for the training and optimization of non-invasive microwave-based breast tumour detection systems. The use of these synthetic models, with similar properties to the biological tissues, is essential in order to evaluate the performance of tumour detection systems in controlled laboratory environments, prior to testing with patients in clinical settings.

In this paper, mixtures of commonly used materials have been used in the implementation of the synthetic tissues. From these mixtures, complex and realistic breast models with two and three layers have been implemented. The developed breast models have been analysed with a microwave medical imaging system. The signals obtained have been processed with complex techniques to detect both the breast tissues and, more importantly, to detect and locate the tumour tissue. The results obtained are promising, predicting good properties of these systems in the detection of breast tumours, especially in the screening phase.

We present a numerical framework to simulate the nonlinear electromagnetic response of biological cells subjected to microwave excitation. Building on recent experimental studies that detect third-order intermodulation products from living cells, our model captures the electrodynamic behavior of membranes via time-dependent conductivity and permittivity changes associated with electroporation. The governing equations are formulated in the time domain, based on a full-wave Maxwell model for TE polarization, and discretized using a semi-implicit scheme coupled with a high-order fast direct solver. Validation against reference solutions in both damped and lossless configurations demonstrates high accuracy and numerical stability. We further illustrate the nonlinear current response of a single cell placed between parallel electrodes under time-varying voltage stimulation. The results highlight the potential of this computational approach to predict nonlinear microwave interactions in cellular environments and to complement experimental microfluidic platforms for future sensing and biomedical applications.

Este trabajo presenta un novedoso sensor de microondas en guía de ondas rectangular no uniforme para la caracterización de las propiedades dieléctricas de materiales. Este describe el principio teórico de funcionamiento del sensor. Las dimensiones de la estructura se han optimizado para caracterizar las propiedades dieléctricas de aceites vegetales. La respuesta del sensor se ha validado midiendo un sustrato sólido con propiedades dieléctricas similares a las de estos aceites. La permitividad relativa del material que rellena la estructura se obtiene mediante la fase del coeficiente de reflexión, que se mide y compara con el análisis teórico y las simulaciones.

This work presents an improved low-cost system for measuring the complex permittivity of liquids and semi-solids using an open-ended coaxial probe. The new system replaces the previous SMA connector with a 0.047" semi-rigid coaxial cable assembly to extend the frequency range up to 20 GHz. The performance of the proposed system is evaluated by comparing measurements of various liquids acetone, methanol, ethanol, propan-1-ol, propan-2-ol, Triton, sunflower oil, saline water, and a 50% water-Triton mixture with those obtained using a commercial open-ended coaxial probe. The results demonstrate the accuracy and reliability of the proposed system, showing excellent agreement with commercial measurements, especially in the frequency range of 500 MHz to 20 GHz. This study highlights the potential of the proposed system as a cost-effective alternative for dielectric characterization, making it suitable for use in laboratories with limited resources.

Accurate sleep stage classification plays a significant role in sleep analysis and sleep disorder diagnosis. Traditional manual annotation of polysomnography (PSG) recordings is labour-intensive and time-consuming, prompting the adoption of automated sleep scoring methods. Although many approaches have been developed, challenges remain in terms of the temporal dependence of PSG signals and computational efficiency. To address these limitations, we propose a novel sleep stage classification model with strong clinical feasibility that balances performance and computational cost. Our method utilises two hierarchical components to process multichannel PSG recordings. First, handcrafted features are extracted in both time and frequency domains in accordance with the American Academy of Sleep Medicine (AASM) guidelines. By including the neighbouring epochs, it preserves temporal correlations. Second, an extreme gradient boosting (XGBoost) classifier is employed for final classification results. Experimental evaluations demonstrate that the proposed model outperforms state-of-the-art approaches in classification performance and computational efficiency, highlighting its potential for real-world clinical implementation.

Computational electromagnetics (CEM) has become essential in aerospace and naval engineering, particularly for analyzing electromagnetic interference (EMI) and compatibility (EMC) in defense applications involving complex platforms. As hyper-sensorization trends emerge, the need for enhanced CEM methods becomes evident to manage electromagnetically dense environments while meeting strict EMC/EMI and radiation hazard (RADHAZ) requirements. Confidentiality concerns pose challenges in information sharing among international partners, complicating the design of subsystems. This work proposes an EPA-based domain decomposition scheme that encapsulates electromagnetic interactions of large-scale platforms using small-scale Huygens’ surfaces. The method significantly improves efficiency and accuracy in the design of antennas and sensors onboard platforms without requiring detailed geometric knowledge. Additionally, it allows assessment of antennas’ contributions to radar cross-section (RCS) while maintaining safety and confidentiality standards. Integrated with advanced techniques based on the domain decomposition method and multitrace (MT) formulations, this approach also ensures robust modeling of near-field interactions among encapsulated objects.

In this work we use the Reduced Basis Method (RBM) as a parametric reduced order model for electromagnetic problems depending on multiple variables. The RBM approach carries out a simultaneous fast sweep in two variables, namely, the frequency and the dielectric permittivity in a dual cavity sensor. This device is aimed to detect dielectric permittivities in the X-band and accurate fast electromagnetic simulations are critical to enhance the sensor performance. This method enables fast EM simulations while maintains the same accuracy as other high-fidelity full-wave methods such as the Finite Element Method.

This work introduces a preliminary exploration of the Finite Element-Boundary Integral (FEBI) method for addressing the scattering problem in open regions. The FEBI method discretizes the wave equation in a region surrounding the scattering object and sets a truncation boundary by imposing that the fields radiated by the currents on the object surface fulfill a Robin-type boundary condition. This, unlike more common approaches such as Absorbing Boundary Conditions (ABCs) or Perfectly Matched Layers (PMLs), allows an asymptotically exact truncation condition with no spurious effects such as internal reflections. Also, it allows placing the truncation boundary very close to the object surface—thus reducing the computational domain—while supporting concave or disjoint boundaries. The formulation presented here is quite general and aims to offer insight into the formal aspects of the method. We also present proof-of-concept examples to illustrate some features of the method, such as the preconditioning.

Efficient and accurate electromagnetic simulations are crucial for the design and optimization of modern microwave devices. However, as the complexity of these models increases, traditional finite element method simulations become computationally expensive, particularly for parametric analyses involving multiple frequency sweeps and material variations. To address this challenge, this work proposes a parametric reduced basis method (pRBM) to accelerate frequency-domain simulations while maintaining the accuracy of the solution. The proposed approach reduces the computational cost by constructing a reduced order model that captures the electromagnetic dynamics of the high-dimensional system.

The effectiveness of the pRBM is demonstrated through the parametric analysis of an inline dielectric resonator microwave filter. Considering angular frequency and dielectric permittivity as parameters, the method efficiently computes frequency responses with a significant reduction in computational effort. These results highlight the potential of model order reduction techniques for accelerating parametric electromagnetic simulations, making them valuable for iterative design processes and large-scale engineering applications.

Time domain electromagnetic (EM) simulations play a crucial role in understanding electromagnetic field behavior across various engineering and scientific applications. However, traditional numerical techniques, including the finite element method in the time domain (FEMTD), require the solution of large systems of equations at each time step, leading to high computational costs. To address this challenge, a reduced order modeling approach based on dynamic mode decomposition (DMD) is proposed. Dominant spatiotemporal patterns are efficiently extracted from FEMTD solutions using DMD, allowing for the construction of a reduced order model (ROM) that significantly accelerates simulations while preserving accuracy. Using an initial set of FEMTD solutions, the DMD-based ROM enables the reconstruction of the EM response at arbitrary time instances with reduced computational effort. This approach also provides valuable information on the dominant structures that govern the evolution of the EM field. The numerical results demonstrate the effectiveness of DMD in reducing computational complexity while maintaining high-fidelity solutions.

This work explores the integration of Artificial Intelligence (AI) models to predict key components of the simulation pipeline of the Fast Multipole Method (FMM).