Numerical study on the distance-dependence of optimal loop size-ratios for inductive coupling links

Loop sizes are critical to the transfer efficiencies of inductive coupling implementations of wireless power transfer. This contribution is a numerical study of the impact of separation distances between coupled loops on the optimal size-ratios of square loops. Closed-form analytic expressions are developed as a basis for a parametric analysis of link performance parameters. The study leads to the development of a simple design equation to enable the direct determination of optimal relative sizing of coupled loops at required separation distances. The performance enhancement arising from the use of analytically-derived loop-size relationships is confirmed through full-wave electromagnetic simulations.