Achieving Many-Fold Reduction in Active Elements with a Highly-Directive Beam-Steerable Huygens Box Antenna

Recent explorations and advancements in communications systems have sparked a renewed fascination with beam-steerable high-gain antennas. While conventional active phased arrays have been long seen as a feasible solution, the associated cost is a major impediment for electrically large millimeter-wave apertures. In this paper, we present an all-metal metamaterial-loaded Huygens box antenna that facilitates independent steering of radiation in azimuth and elevation directions and a dramatic reduction in the number of phased elements. The antenna encloses an artificial dielectric medium with an active Huygens metasurface arranged around the enclosure's periphery. We present simulation and experiment results for a representative 4λ0×4λ0 square aperture, where λ0 is the free-space wavelength. The results show that the antenna radiates similarly to a phased array of similar aperture size, with a quadratic-to-linear reduction ratio in the number of required elements, leading to over 10-fold reduction for large-aperture antennas. The tremendous reduction in the number of excited elements positions the antenna as a cost-saving alternative, especially in large aperture millimeter-wave regime. © 2025 The Author(s)