Design of an ultra-short wave environmental energy harvesting system

In this paper, an ultra-short wave environmental energy harvesting system consisting of a rectifier antenna and a voltage regulator chip is proposed to collect the RF energy at 100-300MHz with an input power of 15-25dBm to obtain stabilized voltage that can be used for charging battery. The size of the rectifier antenna is 274.86mm × 144.38mm, which is miniaturized in the ultra-short wave band by introducing the fourth-order Hilbert fractal structure and the slow-wave cross-finger structure, and it has seven resonance frequency points with S11<-10dB. The rectifier circuit adopts a third-order voltage doubling rectifier circuit to rectify and filter the RF energy in the range of 15-25dBm. The voltage regulator chip consists of three modules: pre-regulator, bandgap voltage reference (BGR) and low-dropout regulator (LDO). The pre-regulator structure reduces the wide range voltage of 3.3-21V obtained after rectification to 3.3-5.1V, and then a stabilized output voltage of 3.27V is achieved through LDO. Experimental results show that the system has great potential for harvesting ultra-short wave RF energy in the environment.