Browsing by Issue Date, starting with "2017-03-19"
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- Characterization of wireless propagation through traditional Iberian brick wallsPublication . Ferreira, David; Caldeirinha, Rafael F. S.; Fernandes, Telmo R.; Cuinas, InigoThis paper presents the wireless transmission properties for brick walls with different thicknesses and facade finish coatings. The ceramic hollowed bricks under study are traditionally employed in the Iberian residential construction, where the 11, 15 and 20 cm thicknesses are most common in indoor and outdoor walls. For each brick dimension, three different prototypes were manufactured varying in the type of wall finish, i.e.: naked brick, smooth painted plaster and rough painted plaster. The prototypes were measured in an anechoic chamber at frequencies ranging from 680MHz up to 10GHz. Results demonstrate that the brick wall internal heterogeneity, as well as the type of finish, significantly influence the frequency response of the walls.
- Enabling spatial diversity and beamsteering with reduced RF-chains using reconfigurable transmitarraysPublication . João R. Reis; Caldeirinha, Rafael F. S.; Fernandes, Telmo R.; Hammoudeh, AkramThis manuscript introduces a new vision on the implementation of spatial diversity with beamsteering capability, by suppressing the typical beamforming networks of antenna phased arrays and replace them by Reconfigurable Transmitar- rays. Consequently, the radio frequency components, i.e. RF- chains that compose such systems, were replaced by a device with the capability to perform two-dimensional beamsteering relying on single antenna source, hence reducing the number of associated RF hardware in comparison with traditional phased array systems. By spatially distributing side-by-side more than one device, spatial diversity with beamsteering is enabled with an estimated reduction of 1:8 in the number of associated RF-chains. This new concept clearly demonstrates its merit by directly reducing the implementation costs„ RF-chain components and increasing the energy efficiency, specially in larger systems.