A Novel Switchable Absorber/Linear Converter based on Active Metasurface and Its Application

In this communication, a switchable active metasurface (SA-MS), with functions for absorption and polarization conversion, is proposed. The metasurface comprises rotated cross loops that are loaded with four sets of parallel-connected lumped resistors and p-i-n diodes on each arm. When the p-i-n diodes are in the OFF-state, the proposed structure performs broadband absorption functions from 3.7 to 10.7 GHz. When the p-i-n diodes are in the ON-state, those parallel lumped resistors are shorted and the structure transforms into a rectangular loop that converts the $x(y)$ - to a $y(x)$ -polarized one from 5.9 to 9.6 GHz. Furthermore, the proposed SA-MS and its mirror symmetry structure are used as the meta-atoms in the chessboard array. Such implementation can achieve backward radar cross section (RCS) reduction based on the phase cancellation principle in the conversion mode without any impact on the absorption function. Moreover, the scattering pattern of the checkerboard structure in the transition mode is more varied than that in the absorption mode. The two different modes provide flexibility for the RCS reduction and enable it to cope with complex electronic reconnaissance. Finally, a chessboard array and uniform array sample printed on the FR4 dielectric layer have been fabricated and measured. The experimental results are consistent with the simulated results.