Ku-Band Liquid-Crystal-Based Frequency Tunable Frequency Selective Surface

A novel frequency selective surface structure (FSS) with reconfigurability based on liquid crystal materials is proposed in this paper. First, to enhance the pass band, a multilayer FSS structure is adopted to form a mixed periodic structure. Furthermore, the coupling of capacitive surface and inductive surface is employed to realize the miniaturization of the structural unit around 0.25λ(λ is the free-space wavelength). A resonant ring structure which can achieve a rapid decline in the passband edge is introduced at the surface of the inductor to enhance the LC series resonance. Finally, the designed FSS has a -15 dB relative bandwidth of 1.27 GHz in the Ku band. As the dielectric constant of the liquid crystal material increases from 2.4 to 3.2, a tuning bandwidth exceeding 1GHz can be obtained. These results demonstrate that the proposed FSS is a good candidate for the radar radome.