Orientation Independent Wireless Power Transfer System Design Utilizing Negative Refractive Index Metasurface

This article proposes a new octagram-shaped meta-atom design having a negative refractive index (NRI) across its operating region 5.71 GHz to 5.90 GHz in the industrial, scientific and medical (ISM) band (5.72 - 5.87 GHz). The corresponding periodic metasurface (MTS) can enhance the power transfer efficiency (PTE) of a circular polarization (CP) based wireless power transfer (WPT) system operating at 5.81 GHz by 9.07%. The proposed NRI MTS can focus the incident waves from the transmitting antenna onto the receiving antenna placed at the focus of the MTS, thereby enhancing the PTE of the system. A circularly polarized square-shaped microstrip antenna (MSA) having orthogonal mode excitation and a diagonally fed rectangular-shaped MSA have been designed to operate as the transmitting and receiving elements, respectively for this proposed rotational orientation independent (CP-based) WPT system. A detailed design flow, along with the parametric study of the proposed meta-atom design as well as the WPT system has been presented based on results from the electromagnetic simulation environment and experimental validation.