Caracterização unificada de antenasnos domínios do tempo e frequência

Abstract

The study of signals in the time domain has been raised last years due to the fast evolution of the computational resources, factor that limited the application of time domain techniques developed last decades. The great advantage of the study of time domain techniques is the ability to work with the electromagnetic quantities without domain transforms. This allows a huge content of frequencies in a certain signal can be analyzed without any discrimination of frequency. Although the interest for broadband systems has increased substantially last years, there is a high demand for systems that works in a small strip of frequencies. So techniques in the spectral domain are more appropriate due to the great development these techniques reached. The objective of this work is the study of parameters that characterize the radiation of electric and magnetic fields for antennas in the time and frequency domain on unifiedrepresentation and directly through a semi-analytical formulation and its subsequent application on the analysis of excited antennas for a temporal behavior arbitrary source. The Effective Height is a parameter for antenna analysis defined for quantities on far field region. The Singularity Expansion Method (SEM) can be used to obtain an unified formulation through the calculation of the current densities. The SEM is capable to model an electromagnetic quantity with the singularities extracted by the currents of the object of study. This work proposes that the singularities are extracted by the Matrix Pencil method applied on the currents obtained numerically through the Method of the Finite Differences in the Time Domain (FDTD) for wired antennas or analytically through Aperture method for reflector antennas and, once obtained the singularities, theformulation of the semi-analytical Effective Height equation is then found.In this work, the analyzed antennas were the dipole, the log-periodic dipole array and the symmetric parabolic reflector. The results were evaluated and validated for consolidated solutions in the literature. The errors and limitations of the method were studied and demonstrated through graphical and analytical representations.