RF Energy Harvesting Using Multidirectional Rectennas: A Review

Radio frequency energy harvesting (RFEH) and wireless power transmission (WPT) are emerging alternative energy technologies that have the potential to provide wireless energy delivery in the future. A key component of RFEH or WPT systems is the receiving antenna, which significantly impacts the power delivery capability of the system. This article extensively examines rectennas designed for multidirectional reception (or wide-angle coverage) of radio frequency (RF) signals with high gain. These rectennas perform better than other types of rectennas when the exact positions of RF sources are unknown or when the sources change location over time. This article classifies rectennas into three categories based on their power combining approach: 1) dc power combining; 2) RF power combining; and 3) hybrid power combining. These rectennas will also be analyzed in terms of angular coverage, size and profile, and gain, as well as polarization, broadband, and multiband performance. The various approaches adopted in the literature to address these challenges are critically analyzed. To this end, based on the gaps in the literature and the lessons learned, we propose the potential open research questions that the researcher can investigate in their research.