Expansão em multipolos esféricos no domínio do tempo aplicada à transformação campo próximo-campo distante

Abstract

This work contains several analyses, tests and studies made to provide knowledge and useful means to speed up the time-domain near-to-far-eld (NFF) transform based on spherical multipole expansion program. Initially, a large and detailed bibliographical review with comments and practical observations about the method were elaborated. The antenna near-eld region surface currents computed by the FDTD (FiniteDierence Time-Domain) method were used as input data. In this way, some NFF transform and FDTD parameters we rechecked in order to reach convergence a long with greater eciency in terms of computational cost. In addition, MPI (Message-Passing Interface) parallel programming implementation allowed to speed up signicantly the program processing. A half-wave length dipole in 10 GHz and a dual band printed quasi-yagi antenna were chosen as test antennas. As one of its main practical contributions, this work developed a statistical analysis technique applied to the NFF transform input data reduction, which could enable to get rid of iterations that add no or negligible accuracy to the nal result. The statistical analysis allowed to generate accurate radiation patterns with 90% data reduction for the half-wave length dipole and 60% for the quasi-yagi antenna. On the other hand, the equations that provide every multipole amplitude are responsable for practically all the method computational cost. In this work, it was found out that each portion of those equation summations displays recurrency patterns among the values assumed in every iteration. Those characteristics would allow to eliminate the iteration with recurrent portions as well as to apply the data reduction techniques with more eciency. Although the developed statistical analysis and the noticed recurrency patterns inpractice have not been applied to the computational cost reduction, they present evidences to be promissing means to eliminate unnecessary iterations and, consequently, to reduce the time-domain spherical multipole NFF transform computational cost.