A Compact High-Efficiency Rectifier With a Simple Harmonic Suppression Structure

In this letter, a compact high-efficiency radio frequency (RF) rectifier based on a series harmonic suppression structure is proposed for wireless power transmission (WPT). The proposed structure removes the cascading bandpass between the RF source and the diode, and the dc-pass filter between the diode and the dc load, simultaneously. The harmonic suppression structure consists only of a short-ended eighth-wavelength microstrip line, which shows an inductive impedance to compensate the rectifying diode's capacitive impedance at fundamental frequency and changes to open circuit to reflect the second harmonic for rectifying again. Two Schottky diodes are used in this design for voltage-doubling rectifying. For fabrication, a rectifier operating at 2.45 GHz was designed, fabricated, and tested. The measurement results show that the maximum RF-dc conversion efficiency is over 80% at 25 dBm. Meanwhile, the fabricated rectifying is compact with 20 mm $\times \,\,{5}$ mm.