Efficient Harvester with Wide Dynamic Input Power Range for 900 MHz Wireless Power Transfer Applications

Abstract

Wireless Power Transfer (WPT), as well as Energy Scavenging and Harvesting, are becoming an active and attractive area of research for scientists and engineers due to the ever-growing need for flexible, sustainable, and unfailing sources of energy. Furthermore, WPT is seen as an environmental solution and a cost-effective approach since it drastically reduces the need to replace and recycle dead batteries. Among existing WPT techniques, RF electromagnetic (EM) techniques, performed through a rectenna, have been retained because of their benefits in transporting power over long distances. Among the rectenna blocks, the diode-based rectifier configuration is the one that significantly influences the performance of WPT systems in terms of maximum Power Conversion Efficiency (PCE). However, such configurations have noticeable limitations like their inability to operate over wide input power range while maintaining an acceptable PCE level. So, to efficiently address the above issues in diode rectifiers, an analysis was first performed to highlight the parameters that prevent the rectifier to operate over a wide range of input power while achieving high PCE at 915 MHz, in the Industrial-Scientific-Medical (ISM) band. From that, different approaches have been proposed to operate over wide range of input power including adaptive/reconfigurable topology, active load modulation, and harmonic trapping. In addition, with the aim to further maximize the rectifier PCE, a dualband rectifier operating at 915 MHz and 2.4 GHz was designed. The fabricated adaptive rectifier exhibits 40% of PCE over a wide dynamic input range of incident RF power levels from -6 to +25 dBm with a maximum PCE of 66% for an input power of +15 dBm. Note that an average error of 1% was observed between simulated and measured results. Finally, a printed patch antenna was designed to evaluate the harvester as rectenna. It achieved a gain of 3 dBi, a directivity of 5.3 dBi and a radiation efficiency of 57%.