Desde sempre, a troca de bens e o transporte de pessoas foram preocupações bem presentes, devido ao impacto no desenvolvimento económico e social de um país. É o caso da indústria ferroviária, que ao longo da História sempre mereceu uma elevada atenção. As empresas responsáveis …
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The overall contribution of the research presented in this dissertation is to introduce a novel method for generating a reconfigurable reflectarray that is based on the creation of photoinduced plasma inside the semiconductor. An optically controlled variable slot located on the…
OFDMA will be the multiple access scheme for next generation networks, including LTE and LTE-A. These networks will provide higher data rates than now, up to several hundred Mbps. These new networks, using a higher carrier frequency and offering flexible bandwidth for different …
UWB technology has been developing in imaging applications. For security imaging applications, it is vital to detect and image metallic targets concealed in bag at airports, subway stations or other public environments. To reduce the cost of the deployment of X-ray machines, a n…
During this PhD study, metamaterials incorporating active devices such as varactors and non-Foster circuits, were researched and designed. Starting from the research on tuneable metamaterials, an electronically controlled leaky-wave (LW) antenna based on composite right/left han…
Novel metamaterial and metamaterial-inspired structures and microwave/antenna applications thereof are proposed and studied in this thesis. Motivated by the challenge of extending the applicability of metamaterial structures into practical microwave solutions, the underlying obj…
Wireless devices, such as mobile phones, personal digital assistants, and Bluetooth headsets emit electromagnetic (EM) radiation. Such devices when used near a user result in EM energy absorption in the head or body of the user. The effect of this absorption is thermal and non-i…