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.