Active Frequency Selective Surfaces Based on Loaded Ring Patches

This paper presents an X-band active frequency selective surface (FSS) based on metal rings loaded with varactor diodes. The FSS unit cell that contains the loaded metal ring resonator is modeled using both an equivalent electrical circuit and a commercially-available full-wave solver. The resonant frequency of the ring is tuned by changing the varactor's capacitance due to the different reverse-bias voltages applied to the varactor diodes. It is shown that these capacitor values in the range from 30 to 65 pF shift the resonant frequency of the FSS from 9.17 to 8.33 GHz. The proposed geometry can be used as an electronically-tunable band-stop FSS.