Two-Dimensional Electromechanically Transformable Metasurface with Beam Scanning Capability Using Four Independently Controllable Shape Memory Alloy Axes

摘要

The advancements in wireless technology, especially in radar detection, where accurate target information is critically needed, have set new standards for antenna subsystems that demand higher gain and full scanning coverage in both the azimuth and elevation planes while maintaining lower cost and design simplicity. The conventional phased array usually requires complex feeding circuitry with large spatial occupancy that renders the system bulky and expensive; therefore, a reconfigurable metasurface may be a suitable alternative. Earlier research outcomes have shown different kinds of reconfigurability in designing metasurfaces for beam steering. Designing electrically reconfigurable metasurfaces using PIN diodes, varactor diodes, etc., is a well-known approach; however, these methods suffer from poor isolation of switches, limited power handling due to nonlinearities, high cost, and complicated biasing networks. This work proposes a novel electromechanically transformable metasurface working as a beam-steering surface with a wider tuning range in the azimuth plane and a simplified independent switching mechanism. The incorporation of four shape memory alloy (SMA) actuator springs allows swift movements in eight different directions. The electrical control of the pitches of the four springs oriented along the four different SMA axes enables adequate mechanical transformation of the 2D metasurface to obtain beam coverage capability.