Low‐frequency miniaturized dual‐band frequency selective surfaces with close band spacing

In this article, a novel miniaturized dual‐band frequency selective surface (FSS) with close band spacing is presented, in which each periodic cell consists of double square loops with different capacitive loadings. The dimension of the unit cell is miniaturized by loading with ceramic chip capacitors. To eliminate the undesired coupling between unit cells, the unit cells are placed in the substrate integrated waveguide cavity structure. As a result, a dual‐band FSS with close band spacing is designed, both simulated and measured results show that the dual‐band FSS operates over DCS1800 (1.8 GHz) and Bluetooth (2.45 GHz) frequency range. And the FSS dimension is miniaturized to 0.114 λ (λ refers to the resonant wavelength of 1.8 GHz). Furthermore, it has very good stability to oblique incidence waves for both TE and TM polarization.