I. Introduction
Recent years have seen a renewal of interest in wireless power transfer (WPT) systems, with applications announced or proposed as varied as contactless charging of batteries in consumer electronics[1], powering of desktop peripherals[2], charging of electric-vehicle batteries [3], and powering of endoscopic robots[4]. Application of such systems in practice, however, involves coils of various geometries and variable orientations. Such variable geometries are often investigated through finite-element analysis (FEA), e.g.,[5]. However, a simple tool for computing mutual inductances between such coils that did not require expertise in FEA or access to FEA software could have significant benefit to the designer of WPT systems.