Abstract: This paper demonstrates the metamaterial enhanced tri-directional coil wireless power transfer (WPT) solution for underwater robots. A tri-directional coil antenna is employed to enable multi-directional WPT and thereby greatly reducing the power loss in a scenario where the transmit-receive coil pairs are misaligned due to random orientation. Furthermore, the impact of parameters such as LOS distance, operating frequency, antenna depth, coil turns, and water conductivity are thoroughly analyzed subject to optimizing the power efficiency in a given environment. Through theoretical verification, we show that superior performance can be achieved using our antenna in contrast to conventional WPT techniques. Additionally, we also validate that operating near the water surface with a low frequency and fewer coil turns maximizes the overall reliability of power transfer in lossy water environments.
