Sub-THz Broadband Transmitting Metasurfaces With Enhanced Frequency-Scanning Capability

In this article, broadband transmitting metasurfaces are developed to enhance frequency-dependent beam scanning. A triple-gold-layer unit cell is designed for wideband transmissions with low losses and quasi-linear phase variations. Comprehensive analyses of phase-gradient metasurfaces are provided to enable high-efficiency and wide-angle frequency scanning. For verifications, two metasurfaces with different phase gradients are simulated, manufactured, and measured. Continuous beam scanning performance has been demonstrated successfully from 80 to 220 GHz, showing beam scanning ranges of 25° and 31.5° from two prototypes, respectively. Peak transmission efficiencies of 84% and 75% have been obtained from experiments. The results from simulation and measurement agree very well. The developed metasurfaces have many potential applications, such as frequency-scanning terahertz imaging.