Switched-beam antennas based on achromatic Huygens metalenses for broadband beamforming and directional reception

Abstract Achromatic metalenses offer promising solutions for advanced wireless systems by enabling compact, high-gain, and directive beamforming capabilities based on switched-beam antenna techniques. Conventional metalenses, however, are prone to chromatic aberrations, where the focal point shifts with frequency, degrading performance across wide bandwidths. In this work, we present a switched-beam antenna based on an achromatic Huygens metalens that maintains a frequency-independent focal length, addressing limitations in prior designs affected by chromatic dispersion. Unlike conventional metalens antennas, our design enables consistent high-gain performance across a wide bandwidth between 8 to 9.7 GHz (19% bandwidth) with a focal length-to-diameter ratio (F/D) of 0.68 and a low-profile, three-metal-layer configuration. We demonstrate the capability of the achromatic metalens antenna as a directional reception system to separate signals from multiple frequency sources based on their angle of arrival, achieving up to 20 dB power separation between different sources. This integration of achromatic focusing and beamforming in a planar, compact structure offers a novel solution for applications in wireless communications, radar and beamforming networks, among others.