Magneto-inductive waveguiding using a step-defect line in a reconfigurable digital metasurface for wireless power transmission

In this paper, we present a reconfigurable digital two-dimensional metasurface consisting of an 8 × 8 matrix of specialized unit cells that can dynamically switch between two resonance modes at 11 MHz and 13.56 MHz. By carefully designing defect-based metamaterial cavities, flexible waveguides are formed while effectively minimizing leakage and transmission losses typically observed in homogeneous structures. Analyses, simulations, and experiments verify that the proposed metasurface enables diverse magneto-inductive wave propagation patterns on a single physical platform under a deep subwavelength mechanism. Furthermore, a step-defect configuration is introduced and experimentally validated, demonstrating its effectiveness in suppressing reflections and impedance mismatch while enhancing transmission efficiency when the receiver is moved to arbitrary positions on the metasurface. The unidirectional waveguide achieves transmission coefficients of S 21 = 0.76 and 0.4, corresponding to source diameter-to-transmission length ratios of 1:1 and 1:8, respectively.