An Active Multifunctional Metamaterial With Four Operating Modes

To improve the flexibility and integration of conventional metamaterials, active multifunctional metamaterials (AMMs) have been intensively investigated in recent years. In this article, a simple but efficient methodology based on equivalent circuits model (ECM) is proposed to design AMMs with four operating modes. The device can be electronically switched between reflective linear-to-linear polarization converter (RLTL-PC), absorber, frequency selective surface (FSS), and transmissive linear-to-circular PC (TLTC-PC) modes. Further, a unit cell (UC) structure consisting of a resistive layer and a double-layer FSS is designed according to the ECM. The operating mode is controlled by electronically tuning the states of p-i-n diodes attached on each layer. The results achieved with ECM calculation are validated against full-wave simulation and a prototype of the proposed AMM is also fabricated and experimentally tested. This work is promising in seeking the all-in-one solution for practical AMM.