Wireless Power Transfer Antenna Alignment Using Third Harmonic

The efficiency of wireless power transfer (WPT) always suffers from misalignment between transmitting and receiving directional antennas. In this letter, a maximum radiation direction alignment method is proposed for WPT using the unexploited third harmonic generated from rectifiers. The widely used second harmonic is untouched, retaining the possibility of its further recycling. A hybrid coupler is used for the received power distributing and third-harmonic coupling simultaneously. Due to the nonlinearity of diodes, the third harmonic is generated during the rectification and reflected back by the rectifier filter. Its power is completely returned to the base station by the same hybrid and another antenna pair working at the third-harmonic frequency. Maximum power transfer is thus realized when both transmitting and receiving antennas are aligned. The proposed method is validated by Advanced Design System simulation and measurement.