Contents I. Introduction
Nikola Tesla proposed the idea of wireless power transmission in the late 19th century [1]. Since the 1960s, there have been many interesting field experiments of beamtype wireless power transmission (WPT) around the world [2], [3]. In particular, since the 1970s, research on using microwaves for beam WPT for solar power stations (SPS) has begun [4]. In 1984, the WPT technology was applied to a patent for car charging [5]. In the 2010s, the standard wireless chargers for mobile phones [6], [7]. In 2015, many papers began to discuss the application of wireless power transmission in the context of the Internet of Things [8]. Until recently, there have been many publications on WPT research. WPT related technologies have always been considered for use, and related research has usually been discussed.
