Dynamic Beam Switching with Shiftable Multimodal Anti-Reflective Coatings

The implementation of non-specular reflection, generally referred to as perfect anomalous reflection, has been the realm of complex periodic metasurfaces consisting of multiple, painstakingly-designed meta-atoms. It has recently been shown that similar effects can be obtained from a basic periodic surface (BPS) with arbitrary properties, coated with several uniform dielectric layers which serve as a multimodal anti-reflective coating (MARC). In spite of its simplicity, the BPS-MARC combination can be easily designed to suppress all components of the discrete propagating Floquet-Bloch (FB) spectrum except the one in the design direction of interest. We show herein that the design direction of the reflected beam can be controlled by simply shifting the MARC relative to the BPS with the aid, for example, of a piezoelectric actuator. Such control enables dynamic beam switching from one radiation angle to another with almost-perfect efficiency. The MARC layers for this purpose are designed analytically and verified by full-wave computations, thus providing a new and conceptually simple method of efficient wave control in real time, highly useful for signal rerouting and multiplexing in reconfigurable antenna systems.