Highly-efficient Compact Size DGS-based Wireless Power Transfer for Low-Power Sensor Nodes

This paper presents the design of a highly-efficient plus-shaped defected ground structure (DGS) based wireless power transfer (WPT) system that is applicable for low-power electronic devices. The prototype, developed on RO4350B op-erates at 0.4 GHz and occupies a board area of 30×30 mm
²
. The proposed WPT system advances the existing state-of-the-art by exhibiting significantly superior figures of merit (FoM). In particular, it possesses a constant efficiency of 86% between 20 mm and 35 mm around the industrial, scientific and medical (ISM) frequency of 0.4 GHz.