Design Theory of a Parallel-Plate Coupler for Underwater Wireless Power Transfer

The design theory of a coupler with two pairs of parallel plates for underwater wireless power transfer is summarized in this paper. The accurate prediction of the power transfer efficiency by separating the $kQ$ product into the coupling coefficient $k$ and Q-factor is a difficult task when transmitting power in a high-permittivity medium, such as water, or a high-conductivity medium such as seawater. Two cases are introduced; the pseudo-coupling coefficient $k$ for fresh water and the pseudo-$kQ$ product for seawater, respectively, are adopted.