Lumped-elements tunable Frequency Selective Surfaces

This paper presents an equivalent circuit model to predict the transmission and the reflection characteristics of different Frequency Selective Surfaces (FSS). The effect of the substrate thickness and permittivity are discussed. A Gridded-Square-Loop (GSL) loaded with lumped-elements is employed to tune the reflection and the transmission characteristics of the FSS. The design method is validated for different polarizations and for different incident angles. In order to tune the response of the FSS, lumped elements (R, L, C) can be inserted in the metallic conductive grid of the FSS. The waveguide simulator method and full-wave simulations are employed to validate the derived analytical equations.