“…Magnetically coupled resonant (MCR) wireless power transfer (WPT) technique has explosively developed over the last decade, and its utilisation has been applied to a broad range of applications, including cell phones and portable devices [1–3], wireless sensor networks [4, 5], unmanned air vehicles [6, 7], robots [8, 9], electrical vehicles [10, 11], biological implants [12, 13] and so on. In addition, the Wi‐Fi‐power technique or WPT with spatial freedom is getting more and more attention [14].…”