Varactor-tunable frequency selective surface with resistive-lumped-element biasing grids

A novel tunable frequency selective surface (FSS) is presented consisting of vertically and horizontally positioned convoluted dipole FSS elements. Each of the latter incorporates a varactor diode, which is biased via novel resistive-lumped-element biasing grids that suppress undesirable resonances and improve the filter´s low-pass response. The proposed design is shown, numerically and experimentally, to perform well. It is expected that this letter will assist research work in low-cost, large-scale tunable FSS.