Programa del congreso

This work presents the preliminary design of a unit cell antenna operating in the L-band (1090 MHz), intended for satellite-based reception of Automatic Dependent Surveillance–Broadcast (ADS-B) signals. The antenna is conceived as a building block for future array configurations within the framework of the SATERA project, an initiative funded by the Horizon Europe programme to enhance air traffic surveillance via satellite technologies. Key performance parameters such as gain, bandwidth, and radiation pattern are evaluated through full-wave simulations. The results demonstrate the feasibility of the proposed concept and provide a solid starting point for its integration into the overall satellite-based ADS-B reception system.

This paper presents the design of a semi-transparent square-ring patch antenna with a monopolar radiation pattern. The antenna's metallic components are implemented using metallized grids, allowing most visible light to pass through. To minimize losses, the design operates without a substrate and consists of a radiating layer formed by a square ring, centrally fed by a coaxial probe through a small patch, along with a ground plane. These layers are interconnected by four shorting walls made of grids, facilitating the excitation of two conical radiation modes that couple to enable wideband operation. The antenna achieves a monopolar radiation pattern over a 35% bandwidth, with gains exceeding 4.5 dBi and transparency levels between 65% and 80%, depending on the grid implementation and ground plane size. This solution is designed for 3D-printed fabrication and integration into vehicle windows or roofs.

Este trabajo analiza cómo la modificación del plano de masa en dispositivos inalámbricos compactos (70 mm × 65 mm) con la tecnología antenna boosters impacta el ancho de banda y la eficiencia total en la banda de 824 – 960 MHz. Se estudian distintas estrategias, incluyendo ranuras y modificaciones estructurales del plano de masa, demostrando que estas técnicas optimizan la distribución de corriente y mejoran la eficiencia. Para validar experimentalmente los resultados de simulación, se fabricaron prototipos, obteniendo mejoras de hasta 2,3 dB en eficiencia. Estos resultados permiten mejorar el rendimiento de antenas en dispositivos con planos de masa eléctricamente pequeños (L < λ/π) , sin necesidad de aumentar su tamaño físico.

The increasing prevalence of Internet of Things (IoT) devices necessitates the development of energy-efficient solutions to prolong battery life and reduce environmental impact. This study explores the potential of using Aloe Vera as a ground plane in IoT device design to enhance antenna performance while minimizing the carbon footprint. By employing Antenna Booster technology, which facilitates device miniaturization without sacrificing efficiency, the research evaluates the feasibility of incorporating an organic Aloe Vera ground plane without compromising performance. Both simulation and experimental results confirm that extending the ground plane with Aloe Vera increases antenna efficiency by 3 dB. These findings highlight the potential of natural materials, such as Aloe Vera, in promoting sustainable improvements in IoT device performance, paving the way for environmentally friendly wireless communication systems.

This paper explores the adaptation of Gutman lenses for array-based feeding systems to overcome the limitations of single-radiator feeding systems, including limited radiated power and restricted beam steering flexibility. The adaptation is achieved through two new methodologies, both based on the analysis of the electric field at the focal plane of the lens. This work presents a proof of concept for these methodologies, providing simulation results and performance evaluations to assess their effectiveness in improving directivity while also examining the impact of lens size on system performance and limitations. Adapting the lens for array-based feeding offers significant benefits for applications such as fixed point-to-point communication systems, where near-broadside scanning and increased radiated power are crucial for mitigating external factors like weather and interference.

Se presenta el diseño de una superficie inteligente reconfigurable (RIS) autosuficiente energéticamente que opera en la banda de 2.4 GHz. La RIS está compuesta por una matriz de 10x10 celdas unitarias (UCs), capaces de captar ondas con polarización dual. Cada celda consiste en un parche planar de dos puertos, conectados a un circuito rectificador y a un circuito desfasador, respectivamente. Las ondas electromagnéticas (EM) con polarización vertical (V-pol) se reflejan en la dirección deseada mediante el uso de un varactor de bajo consumo de potencia, que actúa como carga reactiva controlable permitiendo cambiar la fase de reflexión de cada UC. Por otro lado, la señal incidente con polarización horizontal (H-pol) se utiliza para excitar una red de rectificadores, cuya potencia de salida en DC alimenta los varactores implicados para la redirección. Para lograr una solución compacta, los circuitos asociados al varactor y a los rectificadores se ubican en la parte posterior de cada UC, conectados mediante vías pasantes. El diseño de las UCs, realizado mediante co-simulación no-lineal/EM, predice una pérdida media de 1 dB para una potencia entrante de -10 dBm, mientras que la potencia media de DC extraída en cada UC es de 25 uW, lo que satisface ampliamente los requisitos de potencia de los varactores con un consumo del orden de nW para las operaciones de sintonización. Finalmente, se presentan simulaciones EM de la metasuperficie propuesta de 10x10 UCs que demuestran sus capacidades de redireccionamiento para diferentes ángulos de salida.

In this paper, the conventional equivalent circuit for inductive irises in rectangular waveguide is extended to account the propagation of a second mode at one of the iris terminals. The proposed model is employed to design bandpass filters incorporating cavities in which the TE₂₀₁ resonates. In these cavities, the dominant TE₁₀ mode is used to implement either a cross-coupling or an additional resonator. The proposed circuit facilitates a straightforward and accurate dimensioning process based on simple structures (the irises), while also offering greater design flexibility compared to existing approaches. Experimental results demonstrate that the TE₂₀₁ cavity-based filter presented here achieves significant length reduction and spurious-free range improvement relative to conventional designs.

This work introduces and evaluates the novel mushroom groove waveguide (MGW) as a cost-effective, low-loss alternative to conventional gap waveguides. The MGW and its half-mode variant (HM-MGW) are compared against other established gap waveguide technologies, including the conventional groove gap waveguide (GGW) and its half-mode variant (HM-GGW), both employing traditional metallic pins to emulate a perfect magnetic conductor. This work assesses the performance of an eventual power distribution network across four different realizations, focusing on insertion loss, ease of fabrication, and cost-effectiveness. Experimental measurements corroborate simulation results, offering critical insights for the practical implementation of MGW-based power distribution networks for millimeter-wave band applications.

This work examines the operation of a double-ridge waveguide (DRW) while using for synthesizing impedances. Different analysis were made regarding the frequency operation of a DRW and the impact that its physical dimensions can have in the impedance synthesis. This design comes after the concept of the stepped-impedance line transformer as a cascade of transmission lines with different characteristic impedances, but using, in this particular case, a stepped-ridge waveguide. By the analysis it can be extracted that this structure would be able to synthesize not only real impedances but an arbitrary impedance, following some restrictions explained in this paper.

This work presents an Integral Equation (IE) formulation aimed at analyzing horn antennas connected to a rectangular waveguide microwave filter serving as the input feed structure. To address the IE, the problem is split into two equivalent subproblems: one corresponding to the rectangular waveguide and the other associated with the horn antenna. An equivalent surface magnetic current density (Map) is defined at the discontinuity to establish coupling between the two subproblems. To minimize the total number of unknowns in the Method of Moments (MoM) solution of the IE, Lorentz gauge Green's functions are used, specifically, those corresponding to the rectangular waveguide and to a grounded half-space, respectively. Furthermore, to accelerate the computation of the slowly converging Green’s functions associated with the rectangular waveguide, the Ewald method is applied. The accuracy of the proposed IE method is verified by comparing its predicted radiation patterns and reflection coefficient for a pyramidal horn filtenna against results from the commercial full-wave software Ansys HFSS, demonstrating good agreement and higher computational efficiency.

La eficacia demostrada de las técnicas de radar de apertura sintética interferométricas (InSAR) ha impulsado el desarrollo de misiones satelitales SAR, como BIOMASS y NiSAR, que están preparadas para una amplia aplicación en la monitorización forestal. Sin embargo, las metodologías actuales para la obtención de variables forestales, incluyendo la altura del bosque y la biomasa, presentan importantes limitaciones. Tradicionalmente, la motitorización de bosques requiere una línea de base espacial perpendicular distinta de cero, polarimetría y una línea de base temporal relativamente pequeña (cercana a cero). Este estudio presenta un enfoque novedoso para la extracción de variables biofísicas forestales mediante la modelización de la decorrelación temporal de la coherencia InSAR. Se explora una hipótesis sobre la posible relación entre la decorrelación temporal de la coherencia InSAR y las variables forestales, como la altura de los árboles y la biomasa. Esta hipótesis se pone a prueba en diversas áreas de estudio en Finlandia, Canadá y Alemania. Los resultados sugieren que la decorrelación temporal puede ser un método viable para la extracción de información forestal. Finalmente, se establece una relación clara entre la tasa de decaimiento temporal y variables forestales, como la biomasa del bosque y la altura de los árboles.

Monitoring and detecting the early stages of critical changes and tipping points is essential for effectively adapting to and mitigating their impacts. Some of these early stages could start with important transitions affecting forests’ lower layers before extending and being observable in the upper strata. By using vegetation biomarkers derived from satellite microwave observations, which can penetrate the canopy and offer valuable insights into deeper forest strata, we investigate the spatiotemporal patterns of the Amazon Rainforest over the eleven-year period from 2013 to 2023. Our analysis reveals significant biomass loss within the lower strata of the Amazon Rainforest since 2015/2016, while changes in the upper canopy remain nearly undetectable, highlighting the potential of microwave satellite systems to anticipate imminent forest critical transitions and dieback.

This work describes the potential of Synthetic Aperture Radar (SAR) remote sensing instruments to monitor the vegetation and to extract biophysical and geophysical parameters.

In particular the use of SAR Polarimetry (PolSAR), Interferometry (PolInSAR) and Tomography (TomoSAR) is analyzed in the context of agriculture and forest monitoring.

The ability of SAR sensors to measure the surface reflectivity with the same geometry independently of the weather conditions or the day and night cycle makes it a very useful instrument for reliable time series generation and, therefore, to monitor the Earth's temporal evolution.

Some space-borne missions are available which provide freely accessible SAR data as the ESA Sentinel-1 constellation, operating at C-band but, in the near future, more missions are planned to be launched at different frequencies, as the ESA BIOMASS (P-band) and the ROSE-L (L-band) missions, or the NASA NISAR (L- and S-band).

All these sensors will increase the amount of SAR data available at different frequencies, allowing an unprecedented monitoring of the Earth vegetation and its temporal evolution.

Este estudio presenta una metodología para desagregar los mapas de Humedad del Suelo (SM) de la Iniciativa de Cambio Climático de la ESA de 0.25° a una malla de 60 m, utilizando una red neuronal feedforward. El modelo se aplica sobre la Península Ibérica, abarcando el periodo desde el 2019 hasta el 2022. Este enfoque aprovecha las sinergias entre diferentes variables, incluyendo datos de Sentinel-2, la temperatura de la superficie terrestre de MODIS, la precipitación y evapotranspiración acumuladas de ERA5-Land, la elevación y pendiente del terreno de STRM, y la composición del suelo. Los resultados indican que, a baja resolución el modelo logra una precisión alta sobre los datos de prueba (RMSE=0.03 m³/m³ y R² =0.8). La comparación preliminar entre los mapas de SM a 60 m y las mediciones in situ muestran unas correlaciones en torno a 0.8 y un sesgo que varía entre -0.012 m³/m³ y 0.065 m³/m³.

Brightness temperature measured by low frequency microwave radiometers is sensitive to soil moisture (SM) at different depths, making it useful to estimate root zone soil moisture (RZSM), a key variable for hydrological and agricultural applications. However, existing methods struggle to retrieve SM profiles accurately. This study explores three approaches for SM profile retrieval: the Method of Moments (MoM) and Nyström for solving an inverse problem, and an optimization-based approach. A new flexible SM profile model is also introduced, which does not rely on prior soil information. Results show that VHF radiometer data enhance sensitivity to deeper SM variations, with the optimization approach providing the best accuracy under certain conditions.

La tecnología de radar de apertura sintética (SAR) se encuentra presente en una amplia variedad de misiones de observación de la Tierra. Un ejemplo de ello es el satélite PAZ, encargado de la recopilación de información destinada a defensa, a cartografía de alta resolución o a la gestión de desastres naturales, entre otras. Para garantizar la precisión y fidelidad de los datos, el sistema SAR debe estar calibrado adecuadamente. Si bien existen varios medios para realizar esta calibración, habitualmente se utilizan elementos pasivos como los reflectores de esquina. En este trabajo se estudian distintos diseños y materiales para estos reflectores de esquina con el objetivo de eliminar fuentes de error en la calibración y reducir el alto peso de estos sistemas. En concreto, se estudiará un modelo fabricado en acero que servirá de referencia, un prototipo de aluminio con una nueva geometría y un modelo de ácido poliláctico (PLA) cuya superficie está recubierta con pintura conductora de níquel. Para ello se utiliza el software de simulación electromagnética Ansys Electronics HFSS y la cámara anecoica biestática (BIANCHA) perteneciente al Instituto Nacional de Técnica Aeroespacial (INTA). Además, se presentarán los nuevos diseños fabricados en material compuesto en los que se está trabajando actualmente.

The majority of advancements and research conducted in the field of non-contact vital sign monitoring using radar technology are not suitable for implementation in low-latency, real-time scenarios, such as in apnea monitoring. This paper presents a real time tool implemented in Simulink, which is independent of the radar device, for multiple patient vital sign monitoring, including an apnea detector module. Its performance has been proven using a phase array radar, the AWR21243BOOST, in which the breathing activity in multiple patient scenarios and the detection of apnea episodes have been successfully evaluated.

La monitorización de la marcha puede ayudar a diagnosticar ciertas enfermedades, como el párkinson. Para que sea efectiva, esta debe realizarse en entornos domésticos. Los radares representan una solución prometedora para este propósito, ya que ofrecen fiabilidad sin comprometer la privacidad. La instalación de radares en hogares puede beneficiarse de la extracción inalámbrica de datos, lo que reduce la complejidad de la instalación. Este trabajo presenta tres algoritmos que permiten la extracción de datos de radar FMCW y CW mediante Bluetooth Low Energy (BLE) hacia una unidad de procesamiento externa. Estos algoritmos son extremadamente eficientes desde el punto de vista computacional, ya que se implementan en microcontroladores comerciales de bajo costo. Se evalúan tanto en configuraciones de un solo nodo como en configuraciones multinodo, analizando su rendimiento en términos de relación señal-ruido (SNR) y precisión en los parámetros de la marcha. Este trabajo es relevante para futuras implementaciones domésticas de radar, ya que propone soluciones efectivas y eficientes que facilitan su adopción.

La detección temprana de la enfermedad de Parkinson (EP) es fundamental para mejorar la calidad de vida de los pacientes. La tecnología radar puede ayudar a anticipar su detección mediante la monitorización de la marcha. Sin embargo, ningún estudio ha identificado cuáles son los parámetros de la marcha más relevantes para detectar la EP utilizando radares. En este artículo, se compara la marcha de dos individuos sanos y tres pacientes con EP utilizando una red de radares para determinar qué parámetros de la marcha son más determinantes para detectar la enfermedad. Los resultados muestran que el tiempo medio y máximo de zancada cuando los sujetos caminan a su ritmo habitual son los más determinantes para la detección de la EP. Esta contribución es relevante para futuras implementaciones de redes de radares, ya que señala qué parámetros deben analizarse durante las evaluaciones clínicas.

It is becoming increasingly important for winegrowers to have sensor-generated data to make decisions about vineyard management in a way that improves the quality of the final product. Currently, there are no techniques to measure the volume of grapes in each vineyard and no non-destructive techniques to detect trunk, such as those caused by Esca. This work presents the studies carried out to test the application of SAR and ISAR techniques in the millimeter frequency range in the field of viticulture for the detection of the volume of grapes present on vines as well as for the detection of dry trunk sectors due to the presence of Esca. The measurement setups used and the images obtained by applying the SAR and ISAR algorithms are shown, demonstrating the feasibility of their use in the sector.

This paper presents an experimental comparison of multiple Reconfigurable Intelligent Surface (RIS)-enabled self-localization techniques using Frequency-Modulated Continuous Wave (FMCW) radar. The localization techniques leverage Angle-of-Departure (AoD) and distance estimates from each RIS to enable precise localization of a User Equipment (UE). A dedicated millimeter-wave band demonstrator, incorporating a TI FMCW radar as the UE and a Sivers multiantenna transceiver to emulate RIS functionality, is used to validate the proposed techniques. The results demonstrate the feasibility of self-localization using a limited number of RIS in a linear deployment. Additionally, the robustness of AoD-based and distance difference-based methods against unknown bias errors, introduced due to the physical limitations of the demonstrator, is highlighted. This work identifies the potential of RIS-enabled self-localization in future 6G wireless communication systems, offering insights into the trade-offs between system complexity and localization accuracy in scenarios where no base station is utilized.

En los últimos años, se ha procedido al despliegue de escáneres de seguridad basados en radar MIMO en banda milimétrica para detectar amenazas ocultas en equipajes y bajo la ropa. Sin embargo, enfrentan desafíos tecnológicos debido a la distribución de señales de alta frecuencia, aumentando su complejidad y coste. Este trabajo presenta un radar MIMO en banda D, donde dichas señales se generan localmente en cada nodo. El diseño, basado en MMICs (Monolithic Microwave Integrated Circuits) comerciales con antenas integradas, es compacto y escalable. El sistema combina un radar MIMO horizontal con un barrido mecánico vertical, logrando imágenes 3D a 2-3 metros con resolución inferior al centímetro.

In 5G NR Release 18, 3GPP introduced enhanced demodulation reference signal (DMRS) to support uplink (UL) multiple user (MU) massive multiple-input multiple-output (mMIMO), enabling multiple terminals to transmit simultaneously data over the same time-frequency resources towards a gNB equipped with a large antenna array.

This paper evaluates the performance of UL MU-mMIMO, starting with a detailed analysis of the DMRS framework. We then compare the aggregated throughput to its theoretical limit, considering the typical application of adaptive modulation and coding. Our results show that throughput is strongly influenced by the number of receiving antennas. Additionally, we examine the trade-off between resource allocation overhead and channel estimation processing gain among different DMRS configurations.

Esta contribución presenta un estudio experimental del canal de propagación en interiores en la banda de 8–12 GHz, correspondiente al espectro midband/FR3, a partir de medidas de canal en banda ancha. Se adopta el modelo estadístico de Saleh–Valenzuela (S-V) para caracterizar la dispersión temporal del canal. Las componentes de trayecto múltiple se extraen mediante el algoritmo SAGE, obteniendo estimaciones de su retardo, amplitud y ángulo de llegada. A continuación, se aplican técnicas de agrupamiento basadas en el algoritmo k-means para agrupar dichas componentes y estimar los parámetros del modelo S-V. Los resultados muestran que el modelo S-V describe con precisión el comportamiento del canal en la mayoría de las posiciones del transmisor, permitiendo una representación estadística compacta y significativa del entorno de propagación.

Los sistemas de comunicación acústica submarina (UAC, Underwater Acoustic Communications) son uno de los canales de comunicación más difíciles debido a su inherente selectividad temporal y frecuencial, debida a la dispersión Doppler y a la dispersión por retardo respectivamente, especialmente en aguas poco profundas.

Este trabajo presenta la implementación de un receptor SIMO OFDM (Single-Input Multiple-Output, Orthogonal Frequency Division Multiplexing) empleando modulación QPSK (Quadrature Phase Shift Keying) diseñado para comunicaciones acústicas en aguas poco profundas. El sistema funciona en un rango ultrasónico de banda ancha de 32 kHz a 128 kHz. Se utiliza SIMO para explotar la diversidad espacial con la técnica MRC (Maximum Ratio Combining). Además, incorpora codificación de canal, utilizando un esquema LDPC (Low-Density Parity-Check) para mejorar la robustez de la transmisión. Las prestaciones del sistema se evalúan utilizando señales reales obtenidas a partir de medidas en aguas poco profundas realizadas en el Mar Mediterráneo.

Network Slicing (NS) es una tecnología clave en las redes 5G, ya que permite la creación de redes virtuales personalizadas para satisfacer los diversos requisitos de servicios como Vehicle-to-Everything (V2X) y enhanced Mobile Broadband (eMBB).

Este artículo analiza el impacto de diferentes configuraciones de partición de Physical Resource Blocks (PRBs) en un escenario multi-slice, donde dos segmentos atienden tráfico eMBB y los otros dos atienden tráfico V2X.

Utilizando un simulador de red a nivel de sistema con capacidad de slicing, evaluamos cómo la asignación de PRBs entre los segmentos afecta las métricas clave de rendimiento de la red, y en particular el cumplimiento de los requisitos de latencia para aplicaciones V2X, considerando el retardo experimentado por los paquetes.

Los resultados de este estudio ofrecen información sobre cómo la distribución de PRBs influye en la latencia de V2X y el throughput de eMBB, sentando las bases para futuras estrategias de optimización dirigidas a minimizar la latencia en aplicaciones V2X críticas.

The sensors and cameras in a car are limited to the information that the vehicle receives and processes in its immediate environment and line-of-sight applications. To further extend these data collection capabilities (with the intention of increasing traffic efficiency and safety), Cooperative Intelligent Transportation Systems (C-ITS) technologies are based on the exchange of information between vehicles through wireless communication systems and networks. This paper shows how IDIADA addresses this reality and proposes a pioneering and innovative solution for wireless networks. IDIADA has built a Connected Vehicle Hub, equipped with the latest mobile communication technologies and in compliance with the ETSI ITS G5 standard, to facilitate the construction of increasingly reliable systems, offering its facilities and adapting the platform to the needs of specific test scenarios, in order to repeat tests and evaluations that are difficult or even impossible to perform on the public road due to the constant changes in the road environment and in the networks themselves.

According to the European Road Safety Observatory, annual cyclist fatalities reached 2,035 in 2019 (41\% occurring in rural areas), with serious injuries numbering over 30,000. Innovative automotive systems and road solutions have been proposed to address many safety and emergency issues. These solutions typically involve the introduction of sensors and wireless network communications, the majority based on 5G, and recently, 6G, or 802.11p technologies. However, mobile communication systems coverage in rural areas outside sparsely populated centers is deficient. This deficiency results in many stretches, some extensive, of rural and mountainous roads lacking any form of connectivity, leading to potential communication, navigation, and emergency service access issues. This paper proposes the use of Bluetooth technology to solve the lack of connectivity, implementing a real test-bed and analyzing some key performance indicators as the coverage radio, packet error rate, and latency.

1.183 / 5.000

Las Superficies Inteligentes Reconfigurables (RIS por sus siglas en inglés) han surgido como una tecnología transformadora para los futuros sistemas de comunicaciones inalámbricas, ofreciendo control sobre la propagación de ondas electromagnéticas. Al manipular dinámicamente la fase y la amplitud de las ondas incidentes, las RIS pueden mejorar la cobertura de la señal, optimizar la eficiencia espectral y habilitar capacidades avanzadas de formación de haz, especialmente en frecuencias de ondas milimétricas.

Este artículo presenta el diseño y la caracterización de una novedosa celda unitaria de RIS con forma de bowtie que opera a 29 GHz. A diferencia de los diseños convencionales, esta celda unitaria introduce una geometría única para mejorar el control de fase y minimizar las pérdidas por reflexión. El estudio proporciona un análisis comparativo con una celda unitaria rectangular, demostrando un rendimiento mejorado en términos de amplitud de reflexión, consistencia del desplazamiento de fase y reconfigurabilidad.

Simulaciones de onda completa y mediciones experimentales validan el diseño propuesto, demostrando su potencial para aplicaciones 5G y 6G de próxima generación. Los resultados confirman que la configuración de bowtie ofrece una capacidad de ajuste superior a la vez que mantiene una baja pérdida de inserción, lo que la convierte en una candidata prometedora para implementaciones RIS avanzadas.

Time-Modulated Arrays (TMAs) are known for their ability to reduce side-lobe levels in the radiation pattern at the fundamental (carrier) frequency. However, in this conventional operating mode, TMAs inherently lack beam steering capabilities. This limitation can be overcome by exploiting directional control at harmonic frequencies, enabling beamforming beyond the fundamental tone. In this work, we employ an advanced numerical electromagnetic simulation tool to design and evaluate a TMA that leverages non-ideal stair-step modulation pulses for harmonic beamforming. The proposed design serves as a validation of a previously developed theoretical model by our research group, extending its applicability to arrays composed of realistic, non-isotropic radiating elements. The array’s performance is analyzed using key metrics such as radiated power, radiation intensity, and overall efficiency.

A 8×8 antenna array composed of 2×2 printed patch antenna subarrays is designed for dual-band operation in the Ka-band at 24 and 28 GHz. The key feature of the design is a diplexer-splitter, which enables precise frequency selection, ensuring optimal performance across each band. The feeding network utilizes Inverted Microstrip Gap Waveguide (IMGW) technology, simplifying manufacturing while achieving low losses. The antenna achieves a realized gain of over 25 dBi, making it suitable for 5G networks and other high-frequency applications that require efficient and flexible dual-band operation. Experimental validation is performed to assess the performance of the fabricated prototype, showing good agreement with the simulated results in terms of impedance matching.

This paper presents a dual reflectarray antenna system designed for long-distance communications in the millimeter wave band at 140 GHz. By integrating a main reflectarray with a subreflectarray in a perpendicular feeding configuration, the proposed design mitigates the blockage problems common in densely packed antenna arrays while maintaining a low-cost and lightweight solution. The design methodology emphasizes an optimized phase difference of the radiating elements and an efficient illumination to reduce losses from different sources, achieving a theoretical gain of approximately 38.5 dBi for a 123-mm-diameter reflector. Furthermore, the system demonstrates a minimal gain drop of only 2 dB across the 130–150 GHz range, indicating a promising bandwidth performance.

In this contribution, a conformal electromagnetic skin based on a multi-faceted reflectarray topology has been designed to improve wireless communications in a 5G/6G mm-wave scenario. The proposed structure comprises multiple panels, assembled edge-to-edge following the curved profile of a cylindrical building corner. The multi-faceted electromagnetic skin, which operates in the 28-GHz band, deflects the impinging beam coming from the base station to a specific coverage direction, which is different for each linear polarization. The results of this work demonstrate that the multi-faceted approach can efficiently generate the required coverage in the selected scenario, increasing the integrability with the architectural elements of the environment compared to a traditional single-facet electromagnetic skin

This work proposes the design of spherical reflectarray configurations for satellite antenna applications, in order to achieve a compromise between parabolic and spherical surfaces. The spherical surface simplifies the folding mechanism of the antenna, while the printed elements on the reflectarray surface are designed to correct the spherical aberration, improving the focusing of the spherical surface and providing the electrical performance of a parabolic reflector antenna. The focusing and scanning capabilities of spherical reflectarrays are evaluated and the implementation of spherical reflectarrays in dual antenna configurations is proposed to provide further compact antenna solutions.

This work presents a newly designed antenna measurement facility aimed at enhancing the mm-wave measurement capabilities of UPM’s LEHA. The system comprises a three-axis planar scanner with polarization control, a spherical positioning system, and a reflector-based compact antenna test range (CATR) for mm-wave applications. All mechanical and electrical motion components were custom-designed to compete with commercial solutions. The motor control firmware was developed in-house using an embedded microcontroller with cascaded timers and a DMA coprocessor. The facility’s performance was validated through electrical and mechanical assessments of the spherical near-field range and CATR, demonstrating its capabilities for the W and G frequency bands.

With the advent of new cutting-edge applications such as extended reality, haptics systems or brain-computer interfaces; the future sixth-generation (6G) is expected to reach peak data-rates of about 1 Tbps and latencies below 1 ms. In order to meet these requirements, the recent literature is proposing indoor systems operating in the terahertz (THz) bands, which can provided extremely wide transmission bandwidths. However, these frequencies are not explorated enough in terms of propagation channel characterization. In this work we performed an study and modeling of the path-loss in two corridor scenarios for the ultra-wideband frequency range from 250 GHz to 330 GHz. We observe that path-loss increases log-linearly with distance from 70 dB to 130 dB. Additionally, for distances between transmitter and receiver greater than 7.2 m, an interference pattern appears due to specular components derived from walls and floor reflections. Finally, we apply a power-law model to the experimental path-loss obtaining loss exponents of 2.15 and 2.26; both larger than the expected for free-space.

This paper presents a multi-objective metaheuristic algorithm as a design method to achieve an optimized microstrip patch 2x4 array patch, targeting a resonant frequency of 26 GHz and 0.5 GHz of bandwidth. The optimization adjusts key design parameters through parametric space sampling and iterative evolution of tentative solutions. A Python script interfaces with CST Microwave Studio to automate geometry creation, simulation, and evaluation of two objectives: minimizing the reflection coefficient S11 at the target resonant frequency, and maximizing bandwidth, by ensuring a significant number of frequency points meet the requirement of S11 < -10 dB. The method is first applied to a single patch element, which serves as the foundational block for the array configuration. The array extension leverages the optimized patch parameters as a starting point, followed by a full re-optimization that incorporates array-specific design considerations such as inter-element spacing, phase compensation, gain, and sidelobe level. In order to approximate the Pareto front, the optimization algorithm evolved for 2,000 iterations for the single patch case and 6000 for the 2x4 array. This approach demonstrates the adaptability of this method for advanced 5G/6G antenna designs

Este artículo presenta los últimos avances en los sistemas de medida del laboratorio singular Smart Wireless Technologies, diseñados para la caracterización precisa de dispositivos radiantes y materiales por encima de 100 GHz, en el rango de subTHz. El avance de las comunicaciones ha impulsado la investigación y el desarrollo de dispositivos que operan a frecuencias cada vez más altas, lo que requiere métodos de medición más precisos, rápidos y eficientes. Para abordar estos desafíos, se han desarrollado soluciones innovadoras que minimizan pérdidas, optimizan los tiempos de prueba y mejoran la precisión de las mediciones. En este documento, se realiza una revisión de laboratorios nacionales con capacidades similares y se describen en detalle varios sistemas avanzados de medición del laboratorio singular. Entre ellos, destaca un sistema motorizado en cámara anecoica, diseñado para evaluar antenas con alta resolución espacial y espectral. Además, se presenta un sistema de caracterización de materiales en espacio libre y un sistema especializado para mediciones de Radar Cross Section (RCS), esenciales en aplicaciones de telecomunicaciones, defensa y detección. Estos sistemas mejoran las capacidades del laboratorio y lo posicionan como un referente en la caracterización electromagnética.

In this paper, we study the dynamic formation of transients when plane waves impinge on a dispersive slab that abruptly changes its electrical properties in time. The

timevarying slab alternates between air and metal-like states, whose frequency dispersion is described by the Drude model. It is shown how the physics of this complex system can be well described with the joint combination of two terms: one associated with temporal refractions and the other associated with spatial refractions. To test the validity of the approach, some analytical results are compared with a self-implemented finite-difference

time-domain (FDTD) method. Results show how the transients that occurred after the abrupt temporal changes can shape the overall steady-state response of the space-time system. In fact, far from always being detrimental, these transient states can be conveniently used to perform frequency conversion or to amplify/attenuate the electromagnetic fields.

The Internet of Things (IoT) has revolutionized device interconnectivity in both industrial and home environments. However, the lack of interoperability between proprietary solutions has hindered its widespread adoption. To address this, open standards such as MQTT and later Matter have emerged as leading protocols for smart home applications. This paper presents a comparative analysis of MQTT and Matter, focusing on their architectures and performance in terms of communication latency through an experimental setup designed to measure the response time of both protocols in a real-world domestic scenario.

Hardware acceleration has gained renewed interest recently due to its great potential to solve the computational burdens associated with SW based implementation of real time communication systems. This approach considers SW based implementation of most of the communication functions due to its fast development cycles and great flexibility compared to HW development. However, those functions that are computationally demanding are implemented in HW to greatly reduce the computational time. Due to its iterative nature, channel encoding and decoding is related to high computational costs. This motivated us to develop a solution to this problem by offloading the encoding function to an FPGA. To minimize communication time between the computer and the FPGA, the PCIe interface is used, which achieves high transfer speeds. The results show the encoding of the message both in the computer and in the FPGA, along with their corresponding validation and performance metrics.

En los últimos años, el uso de constelaciones de satélites en Órbita Terrestre Baja (LEO, por sus siglas en inglés) para navegación ha ganado una atención significativa debido a sus ventajas sobre los sistemas tradicionales en Órbita Terrestre Media (MEO), como señales más fuertes, menor latencia y mayor resiliencia. Este artículo presenta el desarrollo de un receptor definido por software de extremo a extremo que aprovecha las señales de Iridium Next en LEO como Señales de Oportunidad (SoOp, por sus siglas en inglés). El flujo de trabajo comienza con la captura de señales en vivo utilizando un Radio Definido por Software (SDR) como interfaz de RF, seguido del procesamiento de las señales capturadas mediante un receptor basado en software. El receptor implementa algoritmos de adquisición y seguimiento para extraer mediciones de Doppler y la intensidad de las señales. Estas observables son evaluadas para determinar su idoneidad en aplicaciones de estimación de posicionamiento, navegación y tiempo (PNT, por sus siglas en inglés), comparándolas con las mediciones esperadas obtenidas mediante la simulación de la dinámica de los satélites. Al aprovechar los desplazamientos dinámicos del efecto Doppler inducidos por el rápido movimiento de los satélites en LEO, este enfoque demuestra su potencial para proporcionar soluciones robustas de navegación en entornos donde las señales tradicionales del GNSS pueden estar indisponibles o degradadas.

Las vocalizaciones de Orcinus orca han sido estudiadas durante mucho tiempo por la comunidad científica. Muchos de estos estudios dependen del monitoreo acústico pasivo, que a menudo implica el procesamiento manual de datos. Automatizar estas tareas podría mejorar el análisis de datos y proporcionar una comprensión más profunda del comportamiento vocal de la especie.

Con el auge de la inteligencia artificial en los últimos años, se han realizado esfuerzos para automatizar tareas clave, principalmente la detección y clasificación.

Este artículo presenta los avances recientes en el sistema desarrollado en Orca Ocean, Loro Parque. Introducimos una infraestructura basada en GStreamer con elementos de inteligencia artificial, capaz de detectar, discriminar y clasificar transmisiones de audio provenientes de hidrófonos en tiempo real durante largos períodos.

Este sistema podría permitir el uso de datos del comportamiento vocal como un indicador adicional del bienestar animal. Además, el estudio de los patrones de secuencias podría mejorar nuestra comprensión de la comunicación de Orcinus orca.

Los sistemas actuales de monitorización acústica pasiva proporcionan grabaciones durante periodos de varios meses, como en el caso de los soundtraps. Estos sistemas pueden provocar una pérdida de contexto en el entorno sonoro y, además, incrementar los costes de fabricación e instalación. Por lo tanto, se ha desarrollado un nodo modular que permite el despliegue de plataformas para la monitorización acústica submarina, capaces de realizar mediciones de energía de banda de larga duración y monitorización en tiempo real, además de permitir la localización y detección de fuentes sonoras.

Estas plataformas se pueden fabricar a bajo coste y los módulos están diseñados para una fácil instalación, flexibilidad y aplicación en diferentes escenarios. La modularidad del diseño se ha aplicado tanto al hardware como al software.

Esta comunicación trata sobre una aplicación de informática forense aplicada a imágenes (vídeo en este caso), donde se utiliza un patrón de ruido característico del sensor de imagen para identificar la cámara fuente (SCI: Source Camera Identification) en vídeos de cámaras web/teléfonos inteligentes. La identificación se basa en el cálculo del ruido intrínseco que siempre está presente en este tipo de dispositivos debido a imperfecciones de fabricación. Esta es una característica inevitable que vincula cada sensor con su patrón de ruido. El patrón PRNU (Photo Response Non-Uniformity) se ha convertido en la técnica más utilizada para realizar identificación de cámaraa. Hoy en día, existen muchas aplicaciones que tratan con patrones de PRNU para la identificación de cámaras utilizando imágenes fijas. En este trabajo, nos centramos en el vídeo, primero en vídeo de cámaars Web y después en vídeo de teléfonos inteligentes. Las cámaras Web y los teléfonos inteligentes son las cámaras de vídeo más utilizadas en la actualidad. En este trabajo, se implementan y evalúan tres posibles métodos para la SCI.

La densificación de la red de acceso radioeléctrico es crucial para el despliegue rápido y eficiente de redes celulares que vayan más allá de la actual red 5G. Este hecho implica integrar celdas pequeñas en zonas donde las macro celdas tradicionales experimentan problemas de cobertura o capacidad. La coordinación y gestión eficaces de estas celdas recién desplegadas son esenciales para garantizar un rendimiento adecuado de la red. Con los recientes avances en inteligencia artificial, esta tarea puede automatizarse mediante técnicas de aprendizaje automático. En este estudio, se propone un método automático para generar listas de celdas vecinas en una red celular basado en redes neuronales de grafos. El modelo propuesto se valida con un conjunto de datos extraídos de una red "Long Term Evolution" (LTE) real. Los resultados demuestran que la metodología propuesta se anticipa con éxito a las listas de vecinas generadas por la función Automatic Neighbor Relations (ANR) y ajustadas por el operador de red.

In beyond 5G mobile networks, the arise of low-power end-devices and data-hungry services with high UpLink (UL) traffic demands makes interference minimization crucial for network operators. Identifying the root cause of interference experienced in a cell is key for effective decision-making. With recent advances in artificial intelligence, such a task can be tackled through supervised learning provided that a labeled training dataset is available. Consequently, automatic data labeling is essential to enable fully automated interference hunting in zero-touch networks. This work presents an algorithm for clustering interference patterns experienced in the UL of a cellular radio access network by root cause through unsupervised learning. The proposed scheme has isolated 13 interference types on a dataset collected in 4 live LTE networks, comprising samples from cells with different bandwidths and radio channel degradation.

This paper presents the design of an automated alarm-based incident prediction system developed in collaboration with Cellnex, the Spanish digital television broadcasting network operator. Due to confidentiality agreements restricting the disclosure of results derived from proprietary data, the system was evaluated using synthetically generated scenarios, Baseline, Degraded, and Alarm-storm, each simulating different network conditions. For each scenario, alarm events are preprocessed, normalized, and encoded into numerical features across four contextual settings: no additional information, pattern sequences, time-based statistics, and their combination. Experimental results show that incorporating temporal context significantly improves incident prediction, particularly in highly imbalanced scenarios. Among the classifiers evaluated, LightGBM consistently achieves the highest balanced accuracy when using time-based statistical features. These results highlight the importance of temporal modeling and imbalance handling in improving alarm-based incident prediction.

Este trabajo presenta un sistema integrado que utiliza drones para identificar y analizar estaciones base en redes de comunicación, combinando tecnologías de posicionamiento GPS, sensores de orientación y aprendizaje automático mediante el modelo YOLOv8 para procesar imágenes capturadas durante el vuelo. El sistema ajusta dinámicamente la altitud del dron y recalcula distancias y direcciones hacia las antenas más cercanas, asegurando una cobertura óptima y una detección precisa incluso en entornos complejos, mientras recopila datos georreferenciados que se exportan a archivos CSV y Excel para su posterior análisis, destacando su potencial para optimizar redes de comunicación asistidas por drones.

For cellular networks, the knowledge of user position is key for improving its services; such as millimetre waves, user-based service or self-healing. The main researches in this area focus on improving the localisation systems, with a special interest in machine learning (ML)-based fingerprinting solutions. Nevertheless, the system performance is measured by prediction RMSE, or other metrics, ignoring any methodology of sensitivity of the system to non-ideal inputs. In this work, statistical-based methods are proposed for characterising the data used for training, the ML model sensitivity and prediction error margins. These aspects are evaluated with a dataset from a commercial mobile network from a European city.

Las redes móviles se enfrentan cada vez más a problemas de congestión en escenarios muy poblados. En este contexto, el despliegue de estaciones base aéreas (ABS) en drones ofrece una solución eficaz y flexible para ampliar la cobertura y aumentar la capacidad de la red sin necesidad de infraestructura fija adicional. Este artículo propone un algoritmo de navegación basado en el aprendizaje profundo por refuerzo (DRL) que optimiza la posición de una ABS para maximizar el cumplimiento del acuerdo de nivel de servicio global. Se comparan cuatro versiones del algoritmo, que se diferencian en la función de recompensa y en los datos utilizados para entrenar al agente DDQN. Los resultados de la simulación muestran que un agente con una función de recompensa basada en mediciones de potencia y entrenado con experiencias recogidas en múltiples entornos logra el mejor rendimiento global, aumentando el cumplimiento del acuerdo de nivel de servicio en un 16,27% en escenarios en los que los usuarios se concentran en una pequeña zona del escenario.

In the design and fabrication of ceramic filters, the quality of metallization is crucial for minimizing resistive losses and ensuring optimal resonator performance. This work presents the design and fabrication of a fully canonical dual-mode monoblock filter, based on BaTiO3 ceramics, operating at S-band frequencies. Sputtering deposition was used to create a 5 nm gold seed layer, on which a 30 μm copper metallization is grown through electroplating. This method guarantees high conductivity in the resonator coating, and the test results demonstrated that the fabricated device offers outstanding filtering performance with a minimal insertion loss of 0.73 dB.

We present a Low Noise Amplifier (LNA) implemented in Silicon-Germanium Heterojunction Bipolar Transistor (SiGe HBT) technology for Band C applications. This SiGe LNA is broadband, covering the frequency range of 4-8 GHz, and achieves a gain of 28 dB. The Noise Figure (NF) of the LNA is 1.5-3.5 dB across the band of interest and an output 1-dB compression point of 10 dBm. The MMIC LNA was mounted and measured to test the similarity with simulations.

RF/Microwave systems require high-speed switches, lower power consumption, smaller footprints, better power handling, and high integration. In this regard, non-volatile switches emerge as a suitable alternative to CMOS- or MEMS-based technologies, mainly due to their ability to maintain a given state without power consumption. In this article, RF memristive switches based on HfO₂ with different active area sizes were developed, fabricated, and characterized. The DC and RF cycling behavior up to 50 GHz was measured and analyzed for various configurations. An 8.1 GHz cutoff frequency was achieved for switches with a 9 µm² active area, and insertion loss lower than -2.1 dB across the entire analyzed frequency range.

Direct synthesis has been shown to provide complete control over the transfer function both in-band and out-of-band. However, finding physically realizable topologies has always been a challenge. This work introduces a methodology to assist in this process, which involves transforming the transversal matrix into a target topology, systematically progressing from the source to the load while applying step-by-step conditions to ensure a manufacturable outcome. User-friendly tools are employed, such as similarity transformations, null eigenvalue splitting, and conditions that allow isolating asymmetries outside the main path of the filter topology to extract the circuital elements. Additionally, the methodology allows for the exploration of an infinite number of possible solutions for a given topology, providing flexibility in the selection of elements to achieve a desired response.

Finding a solution for a given topology in parallel-connected filters can be challenging, particularly due to the existence of multiple possible solutions. This paper introduces a method to handle this solution multiplicity in high-order filters by focusing on the restructuring of the coupling matrix (CM). Unlike traditional approaches that analyze the entire network, this method examines each filter branch separately, where the available solutions are determined by the grouping of eigenvalues within each branch. It is further shown that the analysis may be performed for an inner transversal sub-network by first reconfiguring the N+2 transversal CM to a transversal CM of lower order than N+2. To verify the proposed approach, the results are compared against all known solutions using verification software based on the Numerical Interval Newton Algorithm (NINA), ensuring the global convergence of all solutions. As a demonstration, a 7th-order topology is presented as an example.

This paper presents the design, fabrication and characterization of a Dual-Input Load Modulated Balance Amplifier (LMBA), targeting the efficiency of the amplifier over a wide frequency range (1.4 – 2.1 GHz). This amplifier utilizes load modulation techniques to dynamically adjust the impedance seen by the transistors, ensuring high efficiency even under the amplitude variations typical of modern telecommunications systems, such as those employing QAM modulation. The prototype delivers a saturated power over 39 dBm to the load by both branches with 6 W transistors on RO4003C substrate with ε_r = 3.55 and h = 813 μm. Measurements demonstrate that at saturation, the amplifier achieves 47.7–56.2% Power Added Efficiency (PAE) in saturation and >25% at 9 dB back-off across the 1.4–2.1 GHz band.