Cavity-Excited Switched-Beam Metagrating Antennas

We present a semianalytical scheme to design cavityexcited switched-beam antennas based on printed-circuit-board (PCB) metagratings (MGs), sparse arrays of subwavelength scatterrers (meta-atoms) synthesized via accurate tailoring of mutual coupling. Multiple simple sources embedded in the cavity serve as excitations for a passive multilayered multielement MG superstrate, designed to generate different radiation patterns in response to each of the source ports. The developed synthesis approach utilizes the cavity eigenmode expansion of the source and radiation fields to realize the desired aperture field distribution (and consequently the target radiation patterns). To validate our model and methodology, a switched-beam antenna with three sources is designed and verified in full-wave simulations, exhibiting aperture illumination efficiencies superseding 90% for all three radiation states. This work offers effective and versatile means to implement high-directivity steerable antennas without nonlinear components, especially useful for high-frequency regimes expected in future communication systems.