A Multifunctional Active Frequency Selective Surface With Scattering Diffusivity and Transmission Passband Tunability

In this letter, a multifunctional active frequency selective surface (AFSS) is proposed. In addition to forming several continuously tunable transmission windows in the operating band, it can also maintain low radar cross section (RCS) characteristics out-of-band. Besides, we propose a systematic design method introduced the complete circuit for active lumped elements, which enables the rapid and accurate design of the multifunctional AFSS. The prototype is fabricated and measured. The measured results are in good agreement with the simulated ones. The proposed AFSS can regulate the scattering and radiation characteristics simultaneously and independently, and realize a tunable transmission passband from 3.4 to 6.4 GHz (with a relative bandwidth of 61.2%) and RCS reduction within 8-12.1 GHz. It provides a practical scheme to achieve low RCS while ensuring wideband or multiband antenna radiation performance and a balance between the operating bandwidth with the exposure risk.