Application of EBG (Electromagnetic BandGap) on Frequency Selective Surfaces to Suppress Higher Order Modes
FSS, EBG, Genetic Algorithm, Optimization, and Brillouin Diagram
We propose an application of electromagnetic bandgap (EBG) for suppression or reduction of higher order resonant modes in frequency selective surfaces (FSS), not yet studied in the literature.
The study consists of an application of a rectangular periodic array of circular air holes in 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 holes, aiming to reduce the computational effort during the simulations.
Optimizations with genetic algorithms were implemented to optimize the physical parameters of the holes, aiming at the suppression in the desired frequency range.
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 results measured compared to the simulated results obtained in ANSYS HFSS. A good agreement between the results is observed. Simulations and measurements show suppression levels of up to 6 dB. The simulation time of the FSS with EBG of square holes showed a reduction of 70% in relation to the simulation time of the FSS with EBG of cylindrical holes.