A Compact Duplexing Rectenna With Wireless Power Transfer and Harmonic Feedback Capabilities

A compact duplexing rectenna with wireless power transfer (WPT) and harmonic feedback capabilities is proposed in this work. It cannot only convert the radio frequency (RF) power to the direct current (dc) power at the fundamental frequency, but also feedback the second harmonic signal from power limited receiver side (Rx) to transmitter side (Tx), for the purpose of stabilizing the dc outputs when the dedicated power source is moving. To this end, the duplexing antenna working at 0.915 and 1.83 GHz with good isolation is designed at first. Then, a rectifier with second harmonic signal output is integrated on the ground of the duplexing antenna for a compact size. The rectifier exhibits a measured maximum power conversion efficiency of 58% (at 5 dBm input power) and peak second harmonic signal power of −11 dBm with economic Schottky diodes SMS7630-005LF. Finally, the WPT experiment is carried out. It is demonstrated that the received feedback power increases from −66 to −44.8 dBm monotonically when Tx transmit power varies from 15 to 30 dBm, which proves an effective solution for compact WPT terminal.