Radio Frequency Energy Harvesting System Making Use of 180° Hybrid Couplers and Multiple Antennas to Improve the DC Output Voltage

Abstract

This paper introduces the implementation and experimental results obtained with a radio frequency energy harvester system. A radio frequency combining power circuit based on the characteristic of the 180o hybrid coupler to combine energy is proposed here to be used in radio frequency energy harvesting schemes. Through experimental validations, this proposal demonstrates to offer important advantages compared with other radio frequency energy harvesters found in the literature, including a harvesting voltage enhanced, ease implementation, since is not require any modification in the hybrid coupler,and multi-band function using wideband antennas. The system is designed to harvest energy in the GSM, UMTS, and Wi-Fi frequency bands. The validation of the proposed system using four receiving antennas showed a direct current harvested voltage of 301 mV at 2.5 GHz for an input power of -7 dBm. In addition,the terms of accumulated voltage gain and cumulative efficiency are introduced to evaluate the performance of the proposed combining circuit in radio frequency harvesting schemes.