  Nonreciprocal radiation refers to electromagnetic wave radiation in which a
structure provides different responses under the change of the direction of the
incident field. Modern wireless telecommunication systems demand versatile
apparatuses which are capable of full-duplex nonreciprocal wave processing and
amplification, especially in the reflective state. To realize such a unique,
extraordinary and versatile functionality, we propose an architecture in which
a chain of series cascaded radiating patches are integrated with nonreciprocal
phase shifters, providing an original and efficient apparatus for full-duplex
reflective beamsteering. Such an ultrathin reflective metasurface can provide
directive and diverse radiation beams, large wave amplification, steerable
beams by simply changing the bias of the gradient active nonmagnetic
nonreciprocal phase shifters, and is immune to undesired time harmonics. Having
accomplished all these functionalities in the reflective state, the metasurface
represents a conspicuous apparatus for efficient, controllable and programmable
wave engineering.

Applied Physics;Optics