A compact 35-watt high-efficiency wireless power transmission system under seawater environment

We demonstrate a compact and high-efficiency wireless power transmission system suitable for charging marine sensors, AUV's and electronic devices in the sea. The system, consisted of a rectifier and an antenna, achieved state-of-the-art system efficiency of 40% and high output DC power of 35 W at the distance of 5 cm via sea-water. To determine the operation frequency and power of the system, we investigated attenuation distance and electric field strength. We utilized operation frequency of 1 MHz with an input power of less than 1 KW. The rectifier configuration was designed for undersea operation and achieved a compact size of 50 cm3 and a high efficiency of 80%. The magnetic resonant antenna with a compact size of 25 cm × 25 cm × 5 cm achieved an efficiency of 50% at the distance of 5 cm via sea-water. The proposed system can contribute to realize various kinds of undersea observations.