A Novel Rectenna with Class-F Harmonic Structure for Wireless Power Transfer

The concept of wireless power transfer for powering a low-power electronic circuit is demonstrated in this brief using a novel rectifying-antenna (rectenna). The proposed rectenna is consisted of by a wide-band antenna and a modified rectifier. The antenna bandwidth has been optimized to cover both the f1,= 868 MHz and f2,= 915 MHz UHF-RFID bands. A dual-band Class-F harmonic structure is employed to maximize the power conversion efficiency (PCE) at both the f1 and f2 at low levels of radio frequency (RF) input power (-30 dBm < PIN < 10 dBm) compared to conventional designs. The dual-band class-F harmonic load compensates for the capacitive reactance of the rectifier diodes at the fundamental frequencies (f1 and f2 ) and controls the rectifier output harmonics at 2f1 , 2f2 , 3f1 and 3f2. The proposed modified rectifier depicts a measured maximum PCE of 71% (at f1 ) and 64% (at f2 ) for an RF input power PIN,= 0 dBm with an optimum load resistance (RL ) of 7 kΩ . To demonstrate the proof of concept of wireless powering and validate of the rectenna performance, a DC-DC boost converter, a supercapacitor (COUT,=,370,μ F ), and a low-power electronic circuit is connected to the presented rectenna. According to measured results, the proposed rectenna demonstrates wireless powering of an LED at different distances and various PIN levels (at both the f1 and f2 ). The proposed circuit can be used in wireless power transfer and battery-less wireless sensing systems.