Phase-Continuous Reconfigurable Transmissive Metasurface without Air Gaps.

Reconfigurable metasurfaces, as planar devices with powerful capabilities to regulate, have attracted extensive attention. Conventional phase-continuous reconfigurable transmissive metasurfaces have air gaps, which make the design of metasurfaces more complex. Although several studies have explored metasurfaces without air gaps, their phase-tunable resolution is still not optimal. We present a phase-continuous reconfigurable transmissive metasurface without air gaps based on Huygens' surface theory. The metasurface comprises a multilayer interconnected meta-unit with integrated varactors that can control magnetic resonance characteristics for Huygens' resonance. It achieves 224° continuous phase modulation at 6.7 GHz, the average transmittance of 0.7 at 6.7-7 GHz, and the phase-tunable resolution of approximately 1°/0.1 V. To validate metasurface functional characteristics, beam steering, real-time dynamic focusing, and simultaneous dual focusing are experimentally demonstrated. Both the simulation and experimental results confirm that the proposed metasurface has excellent phase-continuous dynamic reconfigurable capabilities. This advancement will drive the development of metasurface technology, providing support for the next generation of wireless communication and intelligent imaging.