An Optically Controlled Active Frequency Selective Surface with Tunable Passband

This paper presents an optically controlled active frequency selective surface with a tunable passband. The passband can be continuously adjusted by varying the capacitance of varactors, which are powered by photodiodes. The design includes resistors to effectively isolate DC and high-frequency signals. The symmetrical structure ensures polarization insensitivity. The results demonstrate that the passband frequency can be continuously tuned from 5.56 GHz to 2.92 GHz, with a maximum insertion loss of less than 0.6 dB. The proposed structure introduces a novel technique for actively controlling the electromagnetic properties of frequency selective surfaces.