Active-passive compound metasurface for simultaneously manipulating radiation and scattering in a wide band

Metasurfaces, which are usually passive or non-radiating, have provided unprecedented degree of freedom especially for scattering manipulation. For the manipulating radiation, metasurfaces often serve as auxiliaries to radiators since they cannot radiate themselves. Thus, it is unfavorable for integration and miniaturization. In this work, we propose the concept of active-passive compound metasurface (APCM) and explore the possibility of utilizing meta-atoms as active radiators, so as to simultaneously achieve flexible radiation and scattering manipulations at the same time. To this end, a meta-atom structure with large reflection phase-span is delicately designed. In this way, the meta-atom can serve both as wideband radiator fed by a probe and reflection-phase modulator. Flexible scattering-pattern manipulation for one polarization state and high-efficiency radiation-pattern manipulation for the orthogonal polarization state can be simultaneously achieved within the same band from 8.0 to 12.0 GHz. As a proof of concept, two prototypes, one for scattering-cancellation and high-directive radiation while the other for deflected reflection and vortex-beam radiation, were designed, fabricated, and measured, respectively. Both the simulated and measured results verify the active-passive compound design. This work paves an alternative route to integrated multi-functional materials or interfaces and may find wide applications in next-generation communication, radar, smart skin, and others.