7 documents found, page 1 of 1
RF phase shifters design based on barium strontium titanate thick and thin films
Bouça, Patrícia; Pinho, Rui m; Włodarkiewicz, Anna; Tkach, Alexander; Matos, João Nuno; Vilarinho, Paula M.; Carvalho, Nuno Borges deIn this paper, microwave characterizations and phase-shifting applications of electrophoretically deposited thick films and sol-gel derived thin films of Barium Strontium Titanate (BST) are presented. Capacitors fabricated using Ba 0.7 Sr 0.3 TiO 3 films prepared by electrophoretic deposition (EPD) on platinum foils and sol-gel technique on platinized Si and SiO 2 demonstrate a maximum tunability of 49%, 29%, a...
RF-dc Converter Optimization using MIMO Antennas and OTA Multi-Sine Calibration...
Jordão, Marina; Belo, Daniel; Caldeirinha, Rafael; Oliveira, Arnaldo S. R.; Carvalho, Nuno Borges deIn this paper, the optimization of the power transmitted from several non-collocated antennas to an RF-dc converter circuit is performed using an Over-The-Air (OTA) multi-sine feedback method. An experimental system is tested in an indoor environment and the OTA multi-sine calibration method is applied to produce constructive interference at the RF-dc converter location. It is shown that its overall performance...
Mutual coupling reduction using grounded copper vertical plane structure
Bouça, Patricia; Carvalho, Nuno Borges de; Pinho, PedroNowadays, a common concern in 5G communications is the large amount of antennas per array, this is important in mMIMO solutions. This imply a reduction of space between elements, and thus a significant increase in coupling.This paper presents a new solution to reduce mutual coupling in an antenna array. A parametric study was made to determine the influence of mutual coupling depending on the distance between e...
Towards a new baseband processing architecture for next generation software-def...
Silva, Nelson; Oliveira, Arnaldo S. R.; Carvalho, Nuno Borges deA necessidade de melhores rádios, dotados de maior flexibilidade e que facilitem o projecto e verificação levaram a uma mudança de paradigma a favor do Rádio Configurável por Software (SDR). Por outro lado, a implementação de redes sem fio de próxima geração (NGWN) através de SDR irá requerer unidades de processamento com uma eficiência energética muito superior à actualmente permitida. Neste artigo apresentamo...
Medidor de campo electromagnético selectivo na frequência para as bandas GSM900...
Borda, Carlos José; Dias, Rogério Paulo; Carvalho, Nuno Borges de; Matos, João NunoThis paper describes the design, implementation and test of a frequency selective electromagnetic field meter for the GSM900 and GSM1800 bands developed on an engineering degree final project. We will start to introduce all the necessary background concepts such as: biological effects of electromagnetic radiation and reference exposure levels, near and far field and power measurement. Finally, we will present t...
Alternativa ao SPICE para simulação do estado estacionário de circuitos não lin...
Carvalho, Nuno Borges de; Pedro, José CarlosThe objective of this paper is to explain a new technique to simulate non-linear steady-state circuits that does not use time domain, like SPICE[12], but spectral domain to do the simulations. In this paper we develop a new frequency mapping technique to use in the discretization of continuous spectrum and a new tool to do convolution and deconvolution. Finally we prove the validity of this technique.; Pretende...
Network adaptation project for broadband amplifiers
Madureira, Raquel Castro; Carvalho, Nuno Borges de; Pedro, José CarlosEste trabalho visa a descrição de um método de projecto de malhas de adaptação para amplificadores de banda larga, que conduzam a um ganho de transdução constante numa banda previamente definida.