Integrated rectifying circuit and antenna design with harmonic rejection for RF energy harvesting

This paper presents a rectifying antenna (rectenna) which operates at 2.45 GHz. The antenna consists of two-layer low-cost FR-4 substrates separated by an air gap to enhance the gain. The harmonic rejection property is embedded within the antenna design to eliminate the use of harmonic rejection filter (HRF) between the antenna and rectifier, which reduces the cost and size of the rectenna. The rectifying circuit consists of two stages combined by a power combiner to maximize the output voltage. A fast switching Schottky diode of HSMS 286B is used for rectification process. The measured RF-DC conversion efficiency of the proposed rectenna is 78.7% at an input power of 20 dBm and load impedance of 4 KΩ. The proposed rectenna can provide high RF-DC conversion efficiency which is suitable for RF energy harvesting applications.