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

This paper introduces a radio frequency energy harvester system using a radio frequency combining power circuit based on the characteristic of the 180° hybrid coupler to combine energy. 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 multiple wideband antennas. The system is designed to harvest energy in the GSM, UMTS, and Wi-Fi frequency bands. The experimental observations of the proposed system, using four receiving antennas, showed a harvested DC voltage of 847 mV when three sources of radiation close around generates a power of -1.6 dBm in the input of the converter. The conversion stage of the system showed a maximum conversion efficiency of 68% at the frequency of 1.84 GHz. 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 energy harvesting schemes.