Space–Time Metasurfaces for Power Combining of Waves

In passive, linear, and monochromatic systems, complete phase-insensitive combining of powers carried by waves from several input channels into a single output channel is forbidden the energy conservation law. Here, we demonstrate that combination both coherent incoherent plane can be achieved using metasurfaces with properties varying in space time. The proposed structure reflects same frequency but incident at different angles toward direction. frequencies are shifted metasurface, ensuring perfect power combining. concept general applied for electromagnetic microwave to optical domains, as well other physical natures.