Numerical Investigation of a Symmetric-Unit-Cell-Based Tunable Frequency Selective Surface with Stable Angular Response

This work presents a preliminary design of a novel switchable frequency selective surface (FSS) unit cell with an embedded biasing network that preserves electromagnetic symmetry under both TE and TM polarizations. The proposed design addresses the symmetry-breaking limitations commonly caused by conventional control network (CN) layouts in tunable FSSs employing PIN diodes. The unit cell integrates four PIN diodes, all configured in the same state, either ON or OFF, and exhibits a distinct frequency shift along with a switchable band-stop response across the 3–13 GHz band. Full-wave simulations confirm stable angular performance and polarization-independent behavior. The proposed approach offers a compact, planar, and symmetric architecture suitable for future applications in programmable and reconfigurable metasurfaces.