A high angle stable and polarization symmetric dual band reconfigurable frequency selective surface

A dual band reconfigurable active frequency selective surface is designed which resonates at 2.5 and 3.6 GHz as transmission pole frequencies. Lower and upper pass bands have -3 dB bandwidths of 0.4 and 0.5 GHz, respectively. Two notch frequencies are configured from 4.71 to 3.5 GHz and from 2.78 to 2.45 GHz. Dimensions of the unit cell are optimized to lambda (0)/10 calculated at the lowest resonance. The proposed design exhibits insignificant variation at oblique excitation angles until 75 degrees of dual polarized plane wave. An equivalent circuit model is developed for optimization and vivid understanding of the structure behaviour. A prototype of the designed structure is fabricated and the measured response is in satisfactory agreement with the simulated transmission response. High angle stability, low insertion loss at both the transmission pole frequencies, dual band pass/stop tuning for single and dual polarized wave with use of only two varactor diodes are eminent features of the design.