Two-Layer Planar Loop Array for Near Field Beam Forming with Improved Efficiency

This paper presents an efficient two-layer planar loop array resonator for selective magnetic resonance wireless power transfer (MR WPT). This two-layer structure provides two important functions with improved efficiency by adjusting the lumped capacitance of each loop: selective MR WPT, the ability of position- and alignment-free with the receiver. The optimal capacitance of each loop can be found using a genetic algorithm (GA). The two-layer array of 2×2 and 4×4 is designed at an operating frequency of 6.78MHz. This two-layer loop array has improved the measured power transfer efficiency (PTE) by ~10 % at distance of 500mm, compared with that of the previous single-layer 4×4 loop array.