Frequency selective surface based on open trapezoidal rings geometry

In this paper a frequency selective surface, FSS, based on open trapezoidal rings geometry is presented. Composed of four independent open rings, the geometry's characteristics are described and its frequency response discussed, including the polarization effects and how the pairs of rings are excited. Initial project equations are proposed for the first two resonant frequencies. Although these equations are an approximation, a first step for a numerical optimization, differences less than 6% were obtained, when compared to measured resonant frequencies. One advantage of the proposed FSS is the possibility of adjust almost separately the frequency response associated to each pair of open trapezoidal rings. Four FSS were fabricated and characterized, with numerical and measured results verifying a very good agreement. The ease of design, the achieved results, as well the possibility of integrating the open trapezoidal rings with other geometries, instigate the use of the proposed FSS in application such as smart electromagnetic buildings, reconfigurable FSS and so forth.