Design of a Cross-Band Continuously Tunable Frequency Selective Surface With Simplified Feeding Bias Network

Frequency selective surfaces (FSS) are essential components for electromagnetic stealth, polarization conversion, and wireless communication. Despite their versatility, the design of active FSS (AFSS) often encounters challenges with cross-band transition and maintaining performance at lower frequencies. To address these issues, this paper proposed a low-profile, varactor-based AFSS capable of continuous, broadband tunability across L and S bands. By incorporating the feeding structure as a part of the AFSS structure, this structure has a simplified feeding bias network. An accurate equivalent circuit model (ECM) is developed to validate the operating principle of the proposed AFSS. Finally, a sample is fabricated and tested to verify the performance of the device. The measurement results show that the proposed AFSS exhibits passband tunability from 0.97 GHz to 2.92 GHz, with a tunable range of 100.3%. In addition, the proposed structure exhibits polarization independence in both x- and y-polarizations.