An Improved Multifunctional Active Frequency Selective Surface

An improved dual-polarized multifunctional active frequency selective surface (MAFSS) with parallel-feed configuration is proposed in this paper. The designed structure is composed of two metallic layers separated by a thin dielectric layer. Three independent and controllable functions of electromagnetic switching, polarization selection, and frequency tuning are integrated together into the proposed structure via introducing PIN diodes and varactor diodes. To reduce the negative effects of extra feed lines, frequency selective surface (FSS) elements themselves play a significant role in connecting the active components and allowing the direct currents to flow through. A special biasing configuration is designed to provide parallel bias voltages for the two different types of active devices. Finally, an FSS prototype is fabricated and measured, and the measurement results as well as the simulation results both demonstrate great performance of the MAFSS structure. In addition, the proposed structure also performs well under circumstances of oblique incidence and different polarizations.