Fully Polarized Wideband Omnidirectional RF Harvester with Highly Efficient DC Power Combination

Abstract

In this work, an omnidirectional RF energy harvester with wideband coverage (1.5–2.7 GHz), all-polarization, and high-efficiency DC combining is proposed. The harvester integrates six microstrip rectenna elements with varying directions and polarizations. The harvester strategically combines six microstrip rectenna elements with different orientations and polarizations to enhance the stability of omnidirectional energy harvesting. The rectifier employs impedance compression matching techniques, incorporating open-circuited and short-circuited transmission lines to achieve a compact, broadband rectification. Experimental results show that the rectifier maintains an RF-to-DC conversion efficiency exceeding 50% within a bandwidth of 1.5 GHz to 2.7 GHz at an input power of 0 dBm, achieving a maximum efficiency of 62%. The maximum DC-combining efficiency of the rectifier array reaches 92%. These findings indicate that the harvester performs effectively with RF energy of all polarizations from various directions.