Bianisotropic Huygens’ Metasurface Pairs for Nonlocal Power-Conserving Wave Transformations

Bianisotropic Huygens’ metasurfaces are subwavelength thin surfaces that have been used to achieve wide-angle reflectionless refraction of plane waves, among other applications. These metasurfaces can realize any wave transformation, with a lossless and passive structure, provided that local power is conserved over the metasurface at every point. However, there are numerous practical wave transformations that satisfy total power conservation, but break this local power conservation requirement, such as antenna beamforming. In this letter, a method for realizing these wave transformations using a pair of cascaded bianisotropic Huygens’ metasurfaces is proposed. A summation of plane waves is assumed between the two metasurfaces, and their coefficients are obtained based on the stipulated input and output waves. Finally, a case study of converting a cylindrical wave to a truncated plane wave is presented with full-wave simulations.