Tunable bandpass frequency selective surface with embedded biasing

This article presents a tunable bandpass frequency selective surface (FSS) based on varactor diodes. The FSS is made of three metallic layers that are separated from each other by two thin dielectric spacers. Tunability is achieved by loading varactor diodes on the front and back layers. The varactors are connected to the middle layer wire grid and are tuned by applying a bias voltage between the middle and front/back layers wire grids. The proposed tuning concept is validated by fabricating an FSS prototype and testing it in a parallel plate waveguide setup.