Active Frequency Selective Surface With Wide Reconfigurable Passband

This paper presents an active frequency selective surface (AFSS) with a wide reconfigurable passband. The tuning mechanism was investigated with an equivalent circuit which consists of a parallel L-C resonant circuit and a series L-C resonant circuit. A cross-loop slot was selected as a unit cell, and varactor diodes were added across the slot to tune the passband. The effects of various bias configurations on the transmission coefficients were studied. The simulation results showed that a reconfigurable passband ranged from 2.92 to 5.74 GHz was obtained with a variable capacitance from 0.8 to 0.1 pF. A prototype of the proposed AFSS was fabricated and measured. The measurement results showed that the passband was altered from 2.94 to 5.66 GHz if the biasing voltage of varactor diodes was increased from 4 to 18V. The measurement and simulation results agree well with each other.