Dual-Band Tunable Screen Using Complementary Split Ring Resonators

Active frequency selective surfaces (FSS) based on slot-form split ring resonators are described. Switching and tuning have been achieved using two different biasing circuit configurations. The first design switches ON and OFF the two concentric rings separately, producing four distinct transmission responses. The second design is able to vary the capacitance of the two split rings, allowing independent dual-band frequency tuning. The active FSS incorporate commercially available, low cost, surface mount switched PIN diodes and varactor diodes. The operation of the surfaces covers a wide band frequency range within the UHF spectrum, which is desirable for applications such as the modification of the EM architecture of buildings. Measurements compare well with the simulations.