Programa del congreso

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.

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.

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.

This paper presents the design, fabrication and experimental validation of a mechanically reconfigurable 2-bit unit cell for desigining reconfigurable intelligent surface (RIS). An optimized design has been developed, based on the controlled displacement of a metallized movable element driven by a stepper micromotor. This approach achieves a 90º ± 20º phase shift between states with losses below 1.09 dB in the n258 FR2 band of 5G (26 GHz). Additionally, a low-cost fabrication methodology has been carried out, using high-precision SLA 3-D printing and aerosol metallization. Finally, a RIS prototype was characterized in an anechoic chamber demonstrating good agreement between simulated and measured scattering patterns.

Se presenta el diseño de un polarizador dieléctrico conformado esféricamente e impreso en 3D para aplicaciones de comunicaciones en banda Ka. Está compuesto por láminas dieléctricas que siguen una trayectoria loxodrómica, lo que permite la conversión de la polarización lineal de una onda esférica incidente a polarización circular. Cuando el polarizador se ilumina con una antena omnidireccional de polarización lineal según la dirección polar, el polarizador permite radiar una onda esférica con polarización circular a izquierdas, mientras que, si la polarización de la antena es lineal según la dirección acimutal, la conversión de polarización se produce a polarización circular a derechas. Su comportamiento es evaluado con un diseño en el rango 37-40 GHz, en el que se utiliza una antena omnidireccional de doble polarización lineal para excitarlo. Tanto la antena como el polarizador se fabrican mediante técnicas de manufactura aditiva. Los resultados experimentales concuerdan en buena medida con las simulaciones.

Este trabajo presenta una antena monopulso a través de una bocina de fugas (LH) basada en la tecnología de guía de ondas integrada en sustrato (SIW). La LH consta de dos antenas de fuga (LWA) en tecnología SIW separadas angularmente para formar la apertura de la bocina. Diseñando adecuadamente esta separación angular junto a la dirección de radiación de las LWAs, se consigue un frente de onda plano. Para el comportamiento monopulso, se incluye un acoplador híbrido y desfasadores. Dependiendo del puerto de entrada, las LWAs se alimentan en fase o en contrafase generando los patrones suma y diferencia. Se ha fabricado un prototipo para validar el diseño. La bocina presenta una diferencia entre el diagrama de suma y diferencia en el eje de apuntamiento de -25.8 dB, una ganancia máxima de 12.9 dBi, y un ancho de haz de 6.4º a 27.5 GHz.

Este trabajo presenta el diseño y la validación experimental de un filtro de cavidad de guía de onda en banda W que opera en torno a 91\,GHz, empleando una estructura periódica en su banda prohibida con simetría de deslizamiento para implementar el filtro en múltiples láminas metálicas delgadas apiladas sin contacto eléctrico entre ellas. El filtro se basa en cavidades apiladas verticalmente que utilizan el modo TE$_{103}$, lo que ofrece una mayor robustez frente a errores de fabricación y montaje. El filtro propuesto mantiene bajas pérdidas en el rango de frecuencias de 88-94\,GHz, incluso con variaciones de separación entre láminas de hasta 20 micras. El filtro se fabrica mediante corte por láser, con lo que se consigue una baja rugosidad superficial y una gran precisión dimensional. Las mediciones experimentales muestran una excelente concordancia con las simulaciones y demuestran la posibilidad de conseguir filtros de altas prestaciones en frecuencias de ondas milimétricas, manteniendo una baja complejidad y coste de fabricación mediante el uso de la tecnología de guía de onda multicapa combinada con el corte a láser.

This article presents a novel 3D-printed, self-supported coaxial-line X-band filter design. The filter is intended for Earth Observation (EO) data downlink systems, where it must effectively reject signals in a wide frequency range. The filter design incorporates a smooth-profile low-pass filter structure integrated with a short bandpass section with four λ/4 short-circuited stubs. The low-pass section design is optimized by means of shape deformation, including the inner and outer coaxial conductors, and leads to a wide rejection band up to around 40 GHz, to suppress undesired out-of-band frequencies. A prototype was fabricated in one piece using selective laser melting (SLM) and measured, showing excellent agreement with simulations, thus fulfilling the requirements of the target application.

Este artículo presenta el diseño de una antena de lente geodésica metálica integrada con una lente plano-convexa conformada y un polarizador dieléctrico anisotrópico en su apertura. Esta antena está pensada para aplicaciones en ondas milimétricas en la banda Ka (22-40 GHz). La configuración proporciona alta directividad y polarización circular dentro de una cobertura azimutal de ±56º. La lente geodésica está diseñada con 11 puertos de entrada en un extremo y una apertura radiante continua en el otro, dirigiendo el campo electromagnético desde cada puerto de entrada hacia direcciones espaciales específicas, generando así 11 frentes de onda planos distintos en el plano azimutal. La lente dieléctrica plano-convexa en la apertura de la antena colima el plano de elevación, mejorando la directividad de la antena. Además, un polarizador dieléctrico anisotrópico convierte la onda polarizada verticalmente de la lente geodésica en una polarización circular. La antena presenta un ancho de banda relativo del 38,6% (AR < 3 dB), habiendo sido completamente prototipada mediante fabricación aditiva.

En este trabajo se describen los parámetros de diseño, pruebas experimentales y simuladas de un prototipo experimental ArcSAR (Arc-Scanning Synthetic Aperture Radar) embarcado en un vehículo aéreo no tripulado para detección de blancos mediante el escaneo de un entorno permitiendo la localización de estos y evitar posibles obstáculos. Este prototipo que trabaja en bandas milimétricas (24GHz), permite sintetizar la apertura del tamaño de una antena de gran diámetro, a partir del ancho del haz de una antena de diámetro pequeño, característica que le posibilita tener una alta resolución acimutal para discriminación de blancos muy cercanos unos de los otros.

A partir de la evolución y mejora de prototipos ArcSAR terrestres diseñados por el grupo de Microondas y Radar de la Escuela Técnica Superior de Ingenieros de Telecomunicación de la Universidad Politécnica de Madrid, se realizaron modificaciones en lo relacionado a reducción de tamaño, disminución de peso y mayor autonomía, parámetros necesarios para que el prototipo ArcSAR pudiera ser embarcado en un vehículo aéreo no tripulado, mejor conocido como DRON.

This paper presents a Nolen 4x4 matrix beamforming network using lumped elements in the overall matriz; the main application is for the ISM 900 MHz band. The matrix proposed develops a solution with space reduction and good performance. The methodology for design branch line couplers and phase shifters is based on equivalence between transmission lines and lumped elements and it is depicted in the first place. We

fabricated a first prototype to 920 MHz as central frequency and we assembled the matrix over Rogers 4003 Substrate in one layer with lumped elements SMD type of 1005 package. The results show agreement with simulated results, the bandwidth obtained

was approximately 7.3 %; about the radiation patterns over output ports indicate good results in terms of beam scanning. The overall matrix size is 11.4 x 4.1 cm. Hence, this feeding network has the correct behavior for a Nolen 4x4 matrix and the footprint is seven times smaller than if it were developed using microstrip technology.

In this work, the wireless channel was measured in the FR3 band (7 to 24 GHz) using a vector network analyzer and virtual antenna arrays in an indoor environment, under both line-of-sight (LoS) and non-line-of-sight (NLoS) conditions. Path loss values were extracted from measurements conducted at multiple locations across the entire band, as well as within selected sub-bands: 7.125–8.4 GHz, 10–10.5 GHz, 10.7–13.25 GHz, 14.8–15.35 GHz, 17.7–19.7 GHz, and 21.2–23.6 GHz. For each case, the floating-intercept path loss model was fitted. Additionally, a partition loss model was implemented to estimate attenuation under NLoS conditions.

This study presents a mostly experimental work which explores the capabilities of the orbital angular momentum (OAM) waves for near-field (NF) indoors communications in the FR2 regions. With this goal, a well-known T-shaped unit cell is used with a circuital model and analytical expressions where, by changing the ratio of dielectric to air, it is possible to generate the necessary phase shifts to produce OAM waves. Once the transmitarrays (TAs) are designed, several tests are conducted where the orthogonality and the capability of avoiding objects of OAMs is explored. For this purpose, thanks to stereolithography, TAs are 3D-printed in our facilities and measured the orthogonality of the modes with their E-field pattern and the ability to pass through objects.

This paper presents a planar microwave sensor implemented in microstrip technology and operating in transmission. The device is devoted to detecting tiny changes in the dielectric constant of the medium surrounding the sensing element (or material under test -MUT). Such sensing element is a dumbbell defect-ground-structure (DB-DGS) resonator, transversally etched in the ground plane. The operating principle of the sensor is the change in the phase of the transmission coefficient at a specific (operating) frequency caused by variations in the dielectric constant of the MUT. To achieve a high sensitivity, an inductive strip is placed between the access lines, on top of the DB-DGS resonator. By this means, closely spaced resonance and antiresonance frequencies are generated, with the result of a high phase slope in between, a necessary condition for sensitivity enhancement. The maximum sensitivity of the reported prototype is -66.8º per unit of dielectric constant variation, and the figure of merit, or ratio between the maximum sensitivity and the area of the sensing region expressed in squared wavelengths, is FoM = 6243º/λ².

Este trabajo presenta un sensor resonante planar de microondas para medida de concentración de alcohol (etanol y metanol) en agua. El diseño del sensor se basa en la concentración de la energía eléctrica en la región de la muestra mediante un condensador interdigital y una línea de alta impedancia, sin plano de masa, formando una estructura semi-lumped. La respuesta en frecuencia del sensor se puede describir mediante un modelo circuital de elementos concentrados . El sensor se ha estudiado experimentalmente con disoluciones de etanol y metanol en agua, con mejores resultados en términos de sensibilidad para el etanol, en coherencia con las frecuencias de trabajo del sensor, más próximas a la región de relajación del etanol. Las sensibilidades experimentales para tres medidas (frecuencia de resonancia, ancho de banda a 1 dB y nivel mínimo de transmisión), alcanzan valores máximos respectivos de 3,0 MHz/%, 3,67 MHz/% y 0,069 dB/% para el etanol, y de 1,1 MHz/%, 2,10 MHz/% y 0,039 dB/% para el metanol.

Hidden Markov Models (HMMs) have proven to be powerful tools for modeling sequential data across various applications. This paper explores their use in RFID-based tag detection, focusing on improving accuracy and robustness in environments affected by signal noise and interference. We propose a methodology that leverages the probabilistic nature of HMMs to classify and predict RFID tag readings, thereby enhancing detection reliability. The effectiveness of the approach is evaluated through simulations, demonstrating its potential as a cornerstone for improving modern RFID reader performance. Our results indicate that HMMs can significantly reduce inaccuracies, providing a more reliable solution for RFID applications. Additionally, we analyze the impact of model parameters and propose optimizations to enhance performance in dynamic scenarios. This research contributes to the advancement of intelligent RFID systems by integrating probabilistic models for improved tag detection and identification.

In this work, we present an RFID-based indirect soil moisture sensor based on the application of Machine Learning. More specifically, we suggest an unsupervised approach that does not require information about the real height and moisture levels. This approach can be of great interest in practical agricultural deployments, where the careful deployment of tags at specific depths within the soil is challenging. It allows an estimation of the posterior probability of moisture, based on the available Received Signal Strength Indicator (RSSI) and phase. The suggested method enables the RFID system to operate as a sensor by probabilistically quantifying measurement uncertainty, which is a key distinction from existing methodologies. In this paper, we focus on two differentiated moisture cases to show the validity of our approach. Future research will extend the proposed methodology to a wider set of moisture levels.

This paper presents a highly sensitive microwave sensor for bioparticle detection, designed around a ring-gap resonator integrated with a microfluidic channel. The sensor's structure is optimized to enhance electric field confinement, improving its sensitivity to dielectric variations. Experimental validation using commercial microbeads as bioparticle models demonstrates clear resonance shifts, confirming the sensor's capability for precise detection of particles up to 5 µm. These results highlight the potential of the proposed approach for real­time, label-free biosensing applications, offering a promising tool for biomedical diagnostics and analytical chemistry.

With the accelerated growth of online transactions, counterfeiting of various products, such as pharmaceuticals, textiles, and food items, has increased. This work proposes the use of non-cloneable authentication labels for product protection, combining the substrate used and its geometry to obtain a unique spectral response. The labels are manufactured in two steps. In the first, a laser-induced graphene (LIG) layer is formed, which can be implemented using a laser (e.g., CO2 laser) to directly convert various precursors (e.g., polyimide) into graphene. The second step involves an electroplating process that generates traces with variable sheet resistance according to manufacturing parameters. A prototype of a scanner designed to characterize the electromagnetic spectrum is also presented. Results obtained with simple resonators and complex patterns demonstrate the feasibility of this technology.

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.

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.