Higher-order tunable frequency selective surface with miniaturized elements

This article presents a design of tunable frequency-selective surface (FSS) with miniaturized elements. The frequency response of this FSS can be tuned by loading varactor diodes in the unit cell. The varactors are biased with a bias network composed of via holes and wire grids. An equivalent circuit model is utilized in the design process. A second-order tunable FSS prototype is designed and simulated for verification of the tunability concept. Full-wave simulations show a 40% tuning range from 5.1 GHz to 3.4 GHz with an insertion loss between 0.7-5.2 dB within the passband.