A Design of Thin-Layer Frequency Selective Surface with Wideband Tunability and Incidence Stability

In this paper, a thin-layer frequency selective surface (FSS) with wideband tunability and incidence stability is presented. The proposed design is composed of square metallic patches array and grid separated from a thin dielectric substrate where the varactor diodes are placed symmetrically. Adjacent metallic patches are connected with opposite electrodes, so that all varactor diodes are reverse biased in parallel. The results show that continuous modulation in the range of 2.798 GHz to 6.896 GHz (84.5%) can be realized by tuning the external bias voltage. The unit cell dimension is only 0.065λ0, which ensures that it has excellent angular stability within 75 degrees incident angles. Besides, it has stable response on both vertical and parallel polarized wave owing to its symmetry.