Compact dual-band rectenna for RF energy harvest based on a tree-like antenna

Abstract

A novel compact dual-band rectenna is presented for efficient radio frequency (RF) energy harvest at 2.45 GHz WiFi and 3.5 GHz WiMAX bands. The proposed rectenna is composed of an optimised tree-like receiving antenna and a compact rectifier based on a two-branch matching network. The tree-like antenna is found to feature a dual-band characteristic, high radiation efficiency, and improved reflection coefficient with the newly designed slotted ground plane. By introducing the matching network which consists of two different radial branches, the proposed antenna is well matched with the rectifying circuit and most part of the received power could be delivered. Besides, in order to eliminate the coupling effects, reduce the energy loss and minimise the overall dimension of the rectenna, three narrow stubs on the ground plane of the antenna are designed to perform as the ground of the rectifier. The results have demonstrated the designed rectenna exhibits relatively stable conversion efficiency for the load value varying from 0.9 to 20 kΩ under low input power and the maximum conversion efficiency is observed to be 60% at 2.45 GHz and 53% at 3.5 GHz under the input power of 0 dBm.