High-efficiency and compact metamaterial-inspired 900 MHz rectifier

A novel high-efficiency, compact metamaterial-inspired rectifier is proposed for 900-MHz wireless power transmission (WPT) applications. The open-ended composite right/left-handed (CRLH) transmission line (TL) stub, which is introduced to realize metamaterials, replaces the band-pass filter (BPF) of a conventional rectifier (and is smaller than the traditional BPF). The open-ended CRLH TL stub is designed to suppress second- and third-order harmonics and to match the fundamental frequency to a 50-Ω impedance. The device is implemented using lumped elements and a microstrip line. The maximum RF-to-DC conversion efficiency of the proposed rectifier is 69.9% at an input power of 50 mW and a load of 1.8 kΩ. A design procedure that is based on minimizing the phase response of a CRLH TL is presented and validated by simulated and measured results. Because the single CRLH stub is used for harmonic suppression, miniaturization is achieved while retaining efficiency similar to that of previous rectifiers.