Reconfigurable Varifocal Lens Antenna Based on Plasma Technology

The growing demand for higher capacity in wireless communication networks has created a critical need for smart devices with dynamic focusing and beam steering capabilities in the 5G mid-band spectrum. Conventional focusing techniques and metasurface-based flat lenses often suffer from static operation and mechanical complexity, restricting their practical use in adaptive platforms. In this work, we propose a reconfigurable reflective lens based on plasma-filled glass tubes designed to operate at 5 GHz. Through full-wave numerical simulations, we demonstrate that selective modulation of plasma density permits continuous focal length tuning from 1.5λ to 3.5λ. Furthermore, by increasing the number of plasma tubes, we achieve dynamic lateral shifts of the focal spot exceeding 2λ. Compared with prior reconfigurable lens approaches in the microwave and millimeter-wave range, the proposed design offers a broader tuning range and introduces lateral reconfigurability, which has not been previously reported. These results highlight the potential of plasma-based flat lenses as a compact, fast, and energy-efficient solution for integration into next-generation wireless communication systems.