Efficient beam splitting using zero-load-impedance metagratings

Metagratings with zero load impedance are proposed to achieve efficient beam splitting. Different from previously proposed metagratings that require specific capacitive and/or inductive structures to achieve load impedance, the metagrating proposed here consists solely of simple microstrip-line structures. Such a structure overcomes the implementation constraints such that low-cost fabrication technology can be applied for metagratings operating at higher frequencies. The detailed theoretical design procedure is presented together with numerical optimizations to achieve the specific design parameters. Finally, several reflection-type beam-splitting devices with different pointing angles are designed, simulated, and experimentally measured. The results show very high performance at 30 GHz, paving the way to simple and low-cost printed circuit board (PCB) metagratings at millimeter-wave and higher frequencies.