Navegando por Assunto "Electromagnetic scattering"
Agora exibindo 1 - 2 de 2
- Resultados por página
- Opções de Ordenação
Item Acesso aberto (Open Access) Análise e otimização de coberturas de invisibilidade esféricas estratificadas em camadas homogêneas e isotrópicas(Universidade Federal do Pará, 2012-06-29) MARTINS, Tiago Carvalho; DMITRIEV, Victor Alexandrovich; http://lattes.cnpq.br/3139536479960191In this work, we analyze and optimize invisibility cloaks stratified in concentric spherical homogeneous and isotropic layers, in which both the total scattering cross section and the number of layers have been minimized. In order to increase the range of frequencies in which there is invisibility, dispersive effects are taken into account. In microwaves, We obtained discretized invisibility cloaks (obtained from anisotropic cloaks) with significant reductions (greater than 20 dB) of the total scattering cross section, for only 20 layers (which is achieved in the literature with at least 80 layers). We obtained a reduction of 32 dB in the total scattering cross section for a cloak stratified in only 13 layers. This result was obtained in microwaves. In microwaves, we optimized dispersive invisibility cloaks which present a bandwidth 5.4 times larger than would be obtained by a optimized cloak without dispersive effects. Cloaks are designed to operate in optical frequencies, for a wide range of frequencies.Item Acesso aberto (Open Access) Espalhamento eletromagnético no grafeno através de transformadas de impedância(Universidade Federal do Pará, 2019-02-22) PIRES, Andrey Viana; COSTA, Karlo Queiroz da; http://lattes.cnpq.br/7932708321834647Graphene is a two-dimensional material with good electrical properties that make possible new telecommunications applications in telecommunications on the terahertz range. This work presents an alternative analysis of the scattering problem in a graphene sheet using the impedance transform. The Green functions, electromagnetic fields and properties of the plasmonic surface wave on the graphene are demonstrated. The numerical results show the spatial field distributions and spectral analysis of the plasmonic wave as a function of media properties, frequency and chemical potential. The results show that the impedance transform is adequate for scattering analysis in graphene sheets because it uses the natural autofunctions of the problem.