Beamforming power emitter design with 2×2 antenna array and phase control for microwave/RF-based energy harvesting

In this paper, a 915-MHz RF-power emitter with an antenna array controlled by phase shifters is proposed to make directional energy beam point to the energy harvesting (EH) receiver. For the beamforming request, a 2×2 patch antenna array and tunable 360° reflection-type phase shifters are designed. Measurement results show the energy transmission efficiency can be improved by 3.9 times higher than that of single patch antenna at one meter away under the same input power level. Furthermore, by applying ±15° beamforming control, transmission efficiency is increased by 2.7 times when receiving antenna placed at the angle of +24°.