A dual band rectifying antenna for RF energy harvesting

This paper presents a compact dual band rectenna consisting of an open ended microstrip line antenna useful for sensing UMTS and RFID microwave signals. The designed antenna has a Sierpinski fractal geometry loaded on the ground surface and resonates at 2.1 GHz and 5.8 GHz. In the proposed structure, suppression of higher order harmonics is realized with improved RF to DC conversion efficiency in both the resonating bands. A voltage doubler rectifier configuration is used for rectifying the RF signal sensed by means of a receiving antenna and the output is passed through a DC block capacitor. An RF 7 to DC conversion efficiency of 79% and 86% is achieved for a 1 K Omega load at 2.1 GHz and 5.8 GHz, respectively. The overall size of the designed antenna is 40x40x1.6 mm(3) and the rectifier is 40x48.6x0.762 mm(3).