Direct SMA-fed gradient-index metasurface array for efficient microwave power reception

Abstract

Achieving a balance between efficiency and structural simplicity remains a challenge in conventional long-range wireless power reception systems. This study introduces a microwave power reception (MPR) metasurface array based on a gradient-index design. Operating at a center frequency of 5.8 GHz, the array enables efficient conversion and concentration of incident plane waves (PWs) into surface waves (SWs) through cosine-modulated gradient-index units, with a modulation center strategically placed along the array boundary. A key innovation lies in the direct integration of a standard SubMiniature Version A (SMA) connector at the modulation center to collect the concentrated surface wave energy, significantly simplifying the receiving structure and eliminating the need for multiple rectifiers or complex feed networks commonly used in traditional MPR systems. Compared with conventional rectenna arrays, the proposed design achieves a PW-SW conversion efficiency of 68.42%. Simulations, accounting for impedance mismatch at the SMA port, yield an energy collection efficiency of 46.71%, while experimental measurements confirm a peak efficiency of 39.24% at 5.8 GHz. Moreover, the overall system complexity is reduced by over 60%. Although the direct-feed approach introduces impedance mismatch that constrains further performance enhancement, the proposed method offers a low-cost, easily integrable MPR solution that maintains reasonable reception efficiency and simplifies both the design and fabrication processes for specific application scenarios.