Interlayer tuning of X-band frequency-selective surface using liquid crystal

In this paper, a new concept of a voltage-controlled tunable frequency-selective surface (FSS) is introduced based on liquid crystal technology. The designed FSS consists of two periodically patterned metallic layers, separated by a thin dielectric substrate. Tunability is achieved by integrating liquid crystal cells within the substrate for each unit cell, producing interlayer capacitors. By applying a bias voltage between the front and back metallic arrays, the anisotropy axis of the liquid crystal molecules can be re-oriented, and thus the effective relative permittivity of the liquid crystals can be modified to cause a frequency shift in transmission response. Electromagnetic simulations predict 5.6% of continuous frequency tuning for this multi-layer FSS.