A Polarization-Independent Angular-Stable Active Multifunctional Metamaterial for Amplitude Manipulation of Electromagnetic Waves

In recent years, active multifunctional metamaterials (AMFMMs) have been extensively investigated due to their excellent adaptivity to the variation in electromagnetic (EM) environments. However, the existing AMFMMs operate in limited number of modes and narrow operating bands, significantly limiting their range of application. Therefore, this article proposes an efficient methodology for designing the polarization-independent AMFMM with four operating modes for amplitude manipulation of transmitted/reflected EM waves based on the equivalent circuits model (ECM). The unit cell configuration of the proposed AMFMM consists of a switchable frequency-selective surface (FSS) and a switchable impedance layer. The device can be switched between FSS, absorber, frequency-selective rasorber (FSR), and reflector modes, in which the independent switching of TE and TM polarizations is achieved by individually designing biased networks of p-i-n diodes on the switchable FSS and switchable impedance layer. In addition, the proposed AMFMM has excellent angular stability up to a 45° oblique incidence angle. Finally, a prototype of the proposed AMFMM is fabricated and experimentally measured to validate against the full-wave simulation results. This work has great potential in amplitude manipulation of EM waves, reflection shielding, and radar cross section reduction.