Broad-Angle Multichannel Metagrating Diffusers

We present a semianalytical scheme for the design of broad-angle multichannel metagratings (MGs), sparse periodic arrangements of loaded conducting strips (meta-atoms), embedded in a multilayer printed circuit board (PCB) configuration. By judicious choice of periodicity and angles of incidence, scattering off such an MG can be described via a multiport network, where the input and output ports correspond to different illumination and reflection directions associated with the same set of propagating Floquet–Bloch (FB) modes. Since each of these possible scattering scenarios can be modeled analytically, constraints can be conveniently applied on the modal reflection coefficients (scattering matrix entries) to yield a diffusive response, which, when resolved, produce the required MG geometry. We show that by demanding a symmetric MG configuration, the number of independent S parameters can be dramatically reduced, enabling satisfaction of multiple such constraints using a single sparse MG. Without any full-wave optimization, this procedure results in a fabrication-ready layout of a multichannel MG, enabling retroreflection suppression and diffusive scattering from numerous angles of incidence simultaneously. This concept, verified experimentally via a five-channel MG prototype, offers an innovative solution to both monostatic and bistatic radar cross Section (RCS) reduction, avoiding design and implementation challenges associated with dense metasurfaces used for this purpose.