Aplicação de EBG (Electromagnetic Band Gap) em superfícies seletivas em frequência para supressão de modos de ordem superior

Abstract

We propose an application of EBG (Electromagnetic Band Gap) for suppression or reduction of higher order resonant modes in FSS (Frequency Selective Surfaces), not yet studied in the literature. The study consists of the application of a rectangular periodic array of circular air holes in an FSS dielectric substrate to create rejection bands and to suppress or reduce specific resonant frequency modes. Another type of unconventional air hole used was the square shaped hole, aiming to reduce the computational effort during the simulations. To obtain the diameter of the holes and the dimensions of the rectangular patch, an optimization algorithm based on Genetic Algorithms (AG) was used. This procedure was necessary in order to suppress or reduction spurious modes in the frequency of interest of the project. In order to prove that the prohibited bands occurred in the desired frequency bands, a Brillouin dispersion diagram was constructed verifying that the structures acted as EBG. Seven prototypes were manufactured and the measured results were compared with the simulated results obtained in Ansoft HFSS ®. A good agreement between the results is observed. Simulations and measurements show suppression levels of up to 6 dB. The simulation time of FSS with EBG of square holes showed a reduction of 70% in relation to the simulation time of FSS with EBG of cylindrical holes.