Efficient Far-Field Microwave WPT Using GRIN Lens Metamaterial at 2.45 GHz

A gradient refractive index lens metamaterial for enhancement in 2.45 GHz far-field microwave wireless power transfer system efficiency is proposed. The MM unit cell exhibits a magnetic dipole and positive refractive index of 13.73 with minimal imaginary part. The GRIN lens has a parabolic distribution and improves gain by 1.93 dBi when positioned at 153 mm from the transmitter antenna. An experimental investigation of the strategy is validated by comparing the experimental data with the Friis transmission equation for a receiver distance of 1 m. The system efficiency is enhanced to 34.6%, making the GRIN MM suitable for WPT applications.