Terahertz Transmissive Metasurface for Realizing Beam Steering by Frequency Scanning

In this paper, in order to avoid the phenomenon that the diffraction waves cover the incident wave in the reflective frequency-scanning antenna system, which causes insufficient utilization of the beam scanning angular scope, a transmissive planar binary periodical structure metasurface was chosen to achieve frequency-controlled beam scanning, and an approach to realize beam steering with high efficiency was proposed. Specifically, a coherence-enhancing method based on two subcells was proposed to increase conversion efficiency from the incident wave to the diffraction wave. According to the proposed concepts, the frequency scanning antenna based on the transmissive metasurface was designed, fabricated, and measured in the frequency range of 0.25 THz to 0.3 THz. The measured results demonstrate that the designed transmissive metasurface can realize scanning angle 12.5° with comparatively high transferring efficiency. Besides, the proposed transmissive frequency-scanning device also has a lot of unique advantages, such as low cost, simple design and fabrication, which have potential application values in terahertz high frame rate imaging, target detections, communications, etc.