Cálculo de parâmetros otimizados para superfícies seletivas de frequência por meio do método de otimização Taguchi

Abstract

Frequency Selective Surfaces (FSS) belong to a subclass of metamaterial consisting of two-dimensional metallic patches. By presenting a selective frequency behavior, these structures have been applied in the microwave and communication systems fields, in addition it is a research topic by scholars. The literature defines basically the Frequency Selective Surface as a periodic arrangement of patches that displays a certain frequency filtering and it may present characteristics of a band-stop or band-pass filter, which allows the reflection or the transmission of signals in a given frequency range. The FSS are used in diverse applications ranging from microwave and antennas systems to applications in radomes and satellite communications. Researchers have studied FSS structures with appropriate electromagnetic behavior. However, the analysis of spectral characteristics of these structures requires technique with high computational complexity. In order to reduce the computational effort related to the time of processing, it may be used optimization techniques. Concerning to it, this study proposes the use of an optimization method in the FSS design. Optimization methods are intended to get the best results of a system by tuning of the input parameters, that is, when these parameters are adjusted, the optimization methods seek a better output result so that the system performance, in terms of quality, cost and efficiency can be improved. These methods can be applied in various areas. Currently, in the Electromagnetism area, the microwave circuits and antennas have applied various optimization techniques like genetic algorithms (GA), Artificial Neural Networks (ANN) and Particle Swarm Optimization (PSO). The optimization method described in this research was developed based on the concept of the Orthogonal Arrangement, Taguchi Method. This method provides an efficient way to choose the project parameters in a process of optimization and it effectively reduces the number of experiments required in the application. Taguchi method is successfully applied in the chemical engineering and mechanical engineering fields and recently, there have been applications in the Abstract Electromagnetism area, however, its application in FSS is unprecedented. In this study, it was applied the Taguchi Method in three structures of FSS: Square FSS, Square with grid FSS and Cross Dipole. The purpose of the method is to obtain the best values for physical parameters of the FSS, so that is operating in a satisfactory manner, in accordance with certain specifications in the project. It was also used in this research the Equivalent Circuit Method. The accuracy of Taguchi Method is verified experimentally and it is compared to the simulations performed in the ANSYS Designer ®. Then, the prototypes are built and measured in order to validate the experimental results.