Programa del congreso

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

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

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

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