This paper presents the development of a frequency selective surface, FSS, with three bands of rejection, with the central bandwidth applied to the 2.4 GHz frequency band. The three rejection bands are obtained from the association of crossed- dipoles and matryoshka ring geometries. For each geometry the initial design equations are proposed. The procedure to obtain the matryoshka geometry is described step by step. Numerical results are presented for each geometry, and also to the associated geometries, considering different incident angles (θ=0°,15°,30° and 45°). The current distribution of each resonant frequency was shown, allowing to visualize the respective excited geometry. After the numerical results, we verify that the resonant frequencies associated to the respective geometry remains practically unchanged even for the associated geometries. A FSS prototype with the associated geometries was designed, fabricated, and characterized, with a very good agreement between numerical and experimental results, obtaining an attenuation of at least 15 dB in the 2.4 GHz frequency band.

A modeling of the resonant behavior of a continuously reconfigurable frequency selective surface, FSS, is described in this paper. The FSS is based on four arms star geometry and its reconfigurability is achieved by the use of varactors. FSS, four arms star geometry and varactor principles are explained. Considering available a set of measured or numerical data, with frequency responses for different varactor capacitance values, the FSS equivalent circuit is stablished. Then, the varactor capacitance effect is included and the resonant behavior can be easily determined. After stablished, the FSS equivalent circuit can be applied even for a different varactor. In order to validate the proposed modeling, the equivalent circuit of a reconfigurable FSS using the varactor SMV1231 (0.466 pF ≤ Cv ≤ 2.35 pF is obtained. The equivalent circuit results are compared to numerical (ANSYS) and measured results, verifying a good agreement. Following, for the same geometry, the equivalent circuit is applied to a reconfigurable FSS using the SMV1234 varactor (1.32 pF ≤ Cv ≤ 9.63 pF) and once more a good agreement between the results is observed, indicating the applicability of the proposed modeling, which is especially attractive for optimization process.